JP4558056B2 - Electronic imaging device - Google Patents

Description

  The present invention relates to an electronic imaging apparatus, and more particularly to an imaging apparatus including a zoom lens and an electronic imaging element such as a CCD, and more particularly to a digital camera capable of obtaining an electronic image. The present invention also relates to a video camera and a digital camera that have been made thinner in the depth direction by devising an optical system portion such as a zoom lens. In addition, a part of the zoom lens can be rear-focused.

  In recent years, digital cameras (electronic cameras) have attracted attention as next-generation cameras that replace silver salt 35 mm film (commonly known as Leica version) cameras. Furthermore, it has come to have a number of categories in a wide range from a high-function type for business use to a portable popular type.

  In the present invention, focusing on the category of portable popular types, it is aimed to provide a technology for realizing a video camera and a digital camera with a thin depth while ensuring high image quality.

  The biggest bottleneck in reducing the depth direction of the camera is the thickness from the most object-side surface to the imaging surface of the optical system, particularly the zoom lens system. Recently, it has become a mainstream to employ a so-called collapsible lens barrel that projects an optical system from the camera body during shooting and stores the optical system in the camera body when carried.

  However, the thickness when the optical system is retracted varies greatly depending on the lens type and filter used. In particular, in order to set the specifications such as the zoom ratio and F value high, the so-called positive leading zoom lens in which the lens unit closest to the object side has positive refractive power has a large thickness and dead space of each lens element, Even if the lens barrel is retracted, the thickness is not reduced (Patent Document 1).

  The negative leading type zoom lens having 2 to 3 groups in particular is advantageous in that respect, but it is retracted even when the number of elements in the group is large, the thickness of the element is large, or the most object side lens is a positive lens. However, it does not become thin (patent document 2).

  Among the currently known examples that are suitable for electronic imaging devices and have good imaging performance including zoom ratio, angle of view, F number, etc., and the possibility of making the collapsible thickness the smallest, Patent Document 3, There exist patent documents 4, patent documents 5, etc.

  In order to make the first lens group thinner, it is preferable to make the entrance pupil position shallower. For this purpose, the magnification of the second lens group is increased. On the other hand, this increases the burden on the second lens group and makes it difficult to reduce the thickness of the second lens group. In order to reduce the thickness and size of the image sensor, it is only necessary to reduce the size of the image sensor. However, in order to obtain the same number of pixels, it is necessary to reduce the pixel pitch, and the lack of sensitivity must be covered by the optical system. The same is true for diffraction. Also, in order to obtain a camera body with a thin depth, so-called rear focus is effective in terms of the drive system layout instead of the front group for lens movement during focusing. Then, it becomes necessary to select an optical system with less aberration fluctuation when rear focus is performed.

  By the way, conventionally, in an image pickup apparatus using a zoom lens and an electronic image pickup element, in order to adjust the amount of light passing through the zoom lens, a so-called variable diaphragm that changes the aperture diameter has been mainly used.

  On the other hand, with the aim of improving the image quality, the recent increase in the number of pixels of the image sensor is progressing. As the number of pixels of the image sensor increases, the optical performance required for the optical system also increases.

However, when a conventional variable aperture is used, adjusting the light quantity by reducing the aperture diameter has a problem that the resolution decreases due to the influence of diffraction, and it is difficult to achieve both adjustment of the light quantity and high image quality. It was. Further, even when it is desired to reduce the total length of the zoom lens, the thickness due to the mechanical configuration of the variable stop may limit the shortening of the total length of the optical system.
Japanese Patent Laid-Open No. 11-258507 JP 11-52246 A Japanese Patent Application Laid-Open No. 11-194274 Japanese Patent Laid-Open No. 11-287953 JP 2000-9997 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a zoom that has a small number of components, is small and simple in terms of mechanism layout, and has a stable and high imaging performance from infinity to a short distance. Select a method or zoom configuration, and further reduce the total thickness of each group by thinning the lens elements, or considering the selection of filters, so that the zoom lens can be made thin and electronic imaging It is to make the device thinner.

  Another object of the present invention is to provide an electronic imaging apparatus that can adjust the light amount while suppressing the influence of diffraction while maintaining high image quality, and that can shorten the overall length of the zoom lens.

  The electronic imaging device of the present invention that achieves the above object has, in order from the object side, a first lens group that is composed of two lenses and has negative power as a whole, and that is composed of two lenses and has positive power as a whole. The focal length of the entire group can be changed by changing the air gap between the first lens group and the second lens group. From the following conditions (a) to (n) A zoom lens satisfying at least one of the zoom lens, and an electronic image sensor disposed on the image plane side of the zoom lens.

(A) 7 <d _NP · A <27
(B) 20 <t ₁ · A <50
(C) 20 <D ₂ · A <45
(D) 30 <(t ₁ + D ₂ ) · A <90
(E) 30 <−f ₁₁ · A <70
_{(F) 90 <f 12 ·} A <250
(G) 20 <f ₂₁ · A <42
(H) 0.6 <Φ ₂₁ / Φ _w <1.05
(I) 19.5 <R ₂₁ · A <45
(J) 40 <−f ₂₂ · A <140
(K) 0.33 <−Φ ₂₂ / Φ _w <0.80
_{(L) -1 <(R 21} + R 22) / (R 21 -R 22) <0
(M) 0.25 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.4
(N) 72 <ν _d21 <100
However, A = 43.2 / L (L is the diagonal length of the effective imaging region of the electronic imaging device), t ₁ and D ₂ are the total thicknesses on the optical axis of the first lens group and the second lens group, respectively, d _NP is the distance on the optical axis of the two lenses of the first lens group, and f ₁₁ , f ₁₂ , f ₂₁ , and f ₂₂ are the object side lens and image in the two lenses of the first lens group, respectively. Side lens, object side lens in the two lenses of the second lens group, focal length of the image side lens, Φ ₂₁ , Φ ₂₂ , Φ _w are respectively in the two lenses of the second lens group Refracting power of the entire lens at the object side lens, the image side lens, and the wide angle end, R ₂₁ , R ₂₂ , R ₂₃ , and R ₂₄ are curvatures of refractive surfaces in order from the object side constituting the second lens group. The radius, ν _d21, is the Abbe number of the medium of the object side positive lens of the second lens group.

  Another electronic imaging apparatus according to the present invention includes, in order from the object side, a first lens group that includes a negative lens and a positive lens, and has a negative power as a whole, and an aperture stop, a positive lens, Consists of a second lens group consisting of two negative lenses and having a positive power as a whole. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is reduced. The first lens group has an aspherical surface, the second lens group has an aspherical surface on the most object side surface, and satisfies the following conditional expressions (1) and (2), and And an electronic image pickup device disposed on the image plane side of the zoom lens.

(1) 0.6 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.0
(2) 0.08 <t _2N / D ₂ <0.28
Where R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, R ₂₄ is a radius of curvature near the optical axis of the image side surface of the negative lens of the second lens group, and D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and t _2N is the image side of the positive lens of the second lens group. This is the distance on the optical axis from the surface to the image side surface of the second lens group.

  Another electronic imaging apparatus of the present invention includes, in order from the object side, a first lens group having a negative lens on the most object side and a positive lens on the most image side and having a negative power as a whole, and an aperture stop, a positive lens from the object side. When there is a second lens group consisting of two lenses, a negative lens and having a positive power as a whole, and a third lens group consisting of one positive lens, and when zooming from the wide-angle end to the telephoto end, The distance between the first lens group and the second lens group is decreased, the distance between the second lens group and the third lens group is increased, the first lens group has an aspheric surface, and the second lens The group has an aspherical surface on the most object side surface, and the negative lens of the second lens group satisfies the following conditional expression (1), and is disposed on the image plane side of the zoom lens The electronic image pickup device is provided.

(1) 0.6 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.0
However, R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, and R ₂₄ is a radius of curvature near the optical axis of the image side surface of the negative lens of the second lens group. .

  Still another electronic imaging apparatus according to the present invention includes, in order from the object side, a first lens group having a negative lens on the most object side and a positive lens on the most image side and having a negative power as a whole, an aperture stop from the object side, When zooming from the wide-angle end to the telephoto end with a second lens group consisting of two lenses, a positive lens and a negative lens, having a positive power as a whole and a third lens group consisting of a single positive lens The distance between the first lens group and the second lens group is reduced, the distance between the second lens group and the third lens group is increased, the first lens group has an aspheric surface, and the second lens group has an aspherical surface. The lens group has an aspherical surface on the most object side surface, and has a zoom lens that satisfies the following conditional expression (2), and an electronic image pickup device disposed on the image plane side of the zoom lens. Is.

(2) 0.08 <t _2N / D ₂ <0.28
Where D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and t _2N is the thickness of the positive lens of the second lens group. This is the distance on the optical axis from the image side surface to the image side surface of the second lens group.

  Still another electronic imaging apparatus of the present invention includes a negative lens, two positive lenses, or a negative lens, a negative lens, and a positive lens in order from the object side, and has a negative power as a whole. The first lens unit includes a lens unit and a second lens unit that includes an aperture stop, a positive lens, and a negative lens from the object side, and has a positive power as a whole. The distance between the lens group and the second lens group is reduced, the first lens group has an aspheric surface, the second lens group has an aspheric surface on the most object side surface, and the following conditional expression (1) , (2), and an electronic image sensor disposed on the image plane side of the zoom lens.

(1) 0.6 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.0
(2) 0.08 <t _2N / D ₂ <0.28
Where R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, R ₂₄ is a radius of curvature near the optical axis of the image side surface of the negative lens of the second lens group, and D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and t _2N is the image side of the positive lens of the second lens group. This is the distance on the optical axis from the surface to the image side surface of the second lens group.

  Below, the reason and effect | action which take the said structure in this invention are demonstrated.

  The electronic imaging device according to the present invention includes, in order from the object side, a first lens group including two lenses and having a negative power as a whole, and a second lens group including two lenses and having a positive power as a whole. And a zoom lens capable of changing the focal length of the entire group by changing the air gap between the first lens group and the second lens group, and an electron disposed on the image plane side of the zoom lens It has an image sensor.

  The zoom lens satisfies one or more of the above conditions (a) to (n).

  To shorten the lens length when retracted, it is effective to reduce the distance between the two lens elements in the first lens group. However, if the lower limit of 7 of the condition (a) is exceeded, the air generated by the two lenses The effective light passage portion of the lens is not physically established. If the upper limit of 27 is exceeded, the length of the lens when retracted becomes longer and there is no point in reducing the number of lenses to the limit.

  In the condition (a), A is a ratio of the diagonal length of the effective imaging area of the electronic imaging device to the diagonal length of 43.2 mm of one screen of the silver salt 35 mm film, and represents an image plane size conversion factor.

  From another viewpoint, it is effective to reduce the thickness of the entire first lens group. When the lower limit 20 of the thickness (b) on the optical axis of the entire first lens unit is exceeded, the effective beam passage portion of the air lens by the lens rim, middle wall, or two lenses is not physically established. Even if this is not the case, distortion and coma cannot be corrected. If the upper limit of 50 is exceeded, the lens becomes thicker when retracted, and the entrance pupil position becomes deeper and the lens diameter becomes larger, making it meaningless to reduce the number of lenses to the limit.

  Alternatively, the second lens group has the same effect even if the entire thickness is reduced. Also in this case, if the lower limit of 20 of the condition (c) is exceeded, the lens edge and the inner wall will not be physically established. If the upper limit of 45 is exceeded, the lens length when retracted becomes longer, and there is no point in reducing the number of lenses to the limit.

  From another viewpoint, the sum of the total thickness on the optical axis of each of the first lens group and the second lens group may satisfy the condition (d). The troubles when the lower limit of 30 and the upper limit of 90 are exceeded are obvious from the above.

  In addition to reducing the thickness of the lens element and lens group, there is another way to shorten the lens length when retracted. One is to shorten the focal length of the first lens group to the vicinity of the geometric mean of the focal length of the entire system at the wide-angle end and the focal length of the entire system at the telephoto end. That is, the distance between the first lens group and the second lens group can be shortened over the entire zoom range. Then, since the lens frame can be shortened and the diameter of the first lens group can be easily reduced and thinned, the lens length when retracted can be easily shortened. In other words, if the upper limit of 70 of the negative lens condition (e) of the first lens group is exceeded, the diameter of the first lens group becomes large. Then, distortion, coma, curvature of field, chromatic aberration, etc. are likely to occur.

  On the other hand, the positive lens of the first lens group is indispensable for correcting chromatic aberration. If the upper limit 250 of the condition (f) is exceeded, chromatic aberration cannot be corrected, and if the lower limit 90 is exceeded, the power of the first lens group is reduced. Canceled is not preferable. Note that while the angle of view is narrow and the zoom ratio is small, chromatic aberration can be corrected even if the positive lens of the first lens group has no power, so the zoom ratio is 2.5 or less and the wide-angle end angle of view is 66 ° or less. In the case of, it is not necessary to apply.

  Also, the focal length of the second lens group should be as short as possible. This is because the total movement amount during zooming from the wide-angle end to the telephoto end of the second lens group can be small, so that the lens frame can be shortened and the lens length when retracted can be easily shortened. In other words, exceeding the upper limit of 42 in the condition (g) is disadvantageous in shortening the lens length when the lens barrel is retracted, and exceeding the lower limit of 20 causes spherical aberration, coma aberration, or chromatic aberration. It becomes easy to do.

  The condition (g) is applied when the zoom ratio is 2.5 times or less, and when the zoom ratio is 2.5 times or more, the power of the positive lens of the second lens group and the focal length of the entire system at the wide angle end. It is better to apply the condition (h) that defines the ratio. If the lower limit of 0.6 is exceeded, the overall length of use will be longer, which is disadvantageous for shortening the retracted lens length. If the upper limit of 1.05 is exceeded, spherical aberration, coma aberration, or chromatic aberration will occur. It becomes easy to do.

  As another way of thinking, a method of reducing the radius of curvature on the object side of the positive lens in the second lens group within the range of condition (i) may be used. Exceeding the upper limit of 45 is disadvantageous in shortening the lens length when retracted because the total length of use is long, and exceeding the lower limit of 19.5 tends to cause spherical aberration, coma aberration, chromatic aberration, and the like.

  On the other hand, the negative lens of the second lens group is indispensable for correcting chromatic aberration. If the upper limit of 140 of the condition (j) is exceeded, chromatic aberration cannot be corrected, and if the lower limit of 40 is exceeded, the power of the second lens group is exceeded. Canceling is not preferable. If the zoom ratio is 2.5 times or less, there is no problem even if the zoom ratio is out of the range.

  Alternatively, the ratio between the power of the negative lens of the second lens group and the focal length of the entire system at the wide-angle end may be defined as in the condition (k). If the lower limit of 0.33 is not satisfied, chromatic aberration cannot be corrected. If the upper limit of 0.80 is exceeded, the power of the second lens group is canceled, which is not preferable. If the zoom ratio is 2.5 or less and the wide-angle end field angle is 66 ° or less, there is no problem even if it is out of the range. In order to shorten the lens length when retracted, it is effective to reduce the thickness of each group or increase the power. However, if these are to be realized, aberration correction becomes difficult as a general tendency. In other words, if aberration correction can be performed by some means such as introduction of an aspherical surface, it can be made as short as physically possible. That is, it is effective to define the shape of the lens element of the second lens group. When the upper limit value 0 of the condition (l) that defines the shape of the second lens group positive lens is exceeded, coma aberration tends to be positive, and spherical aberration also increases. When the lower limit of −1 is exceeded, coma tends to be positive, and spherical aberration also increases. It should be noted that when the zoom ratio is 2.5 or less, even if the zoom ratio is out of the range, both spherical aberration and coma aberration can be sufficiently corrected, so that it is not necessary to apply. If the upper limit of 3.4 of the condition (m) that defines the shape of the second lens group negative lens is exceeded, the image surface cannot be kept flat, and if the lower limit of 0.25 is exceeded, spherical aberration due to higher-order components Will increase.

  Similarly, with respect to chromatic aberration, if the lower limit of 72 of the condition (n) is exceeded, it is difficult to correct longitudinal chromatic aberration and lateral chromatic aberration. If the upper limit of 100 is exceeded, there is only a lens material that is very difficult to supply. When the angle of view is narrow and the zoom ratio is small, that is, when the zoom ratio is 2.5 or less and the wide-angle end angle is 66 ° or less, chromatic aberration can be corrected even if the condition (n) is not satisfied. Therefore, it is not necessary to apply.

  As described above, among the conditions (a) to (n), the more satisfied the condition, the shorter the lens length when retracted.

  In addition, if the range of each condition is individually or simultaneously as follows, it is more advantageous to shorten the lens length when retracted.

(A) '7 <d _NP · A <24.6
(B) '20 <t ₁ · A <45.2
(C) '20 <D ₂ · A <42.5
(D) '30 <(t ₁ + D ₂ ) · A <84
(E) ′ 30 <−f ₁₁ · A <66.7
(F) '90 <f ₁₂ · A <240
(G) '20 <f ₂₁ · A <41
(H) '0.6 <Φ ₂₁ / Φ _w <1.02
(I) '19.5 <R ₂₁ · A <40
(J) '47 <−f ₂₂ · A <140
(K) ′ 0.33 <−Φ ₂₂ / Φ _w <0.75
(L) '-1 <(R 21 + R 22) / (R 21 -R 22) <- 0.1
(M) ′ 0.5 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3
(N) '72 <ν _d21 <96
Furthermore, it is more preferable if the range of each condition is limited as follows.

(A) ”7 <d _NP · A <20
(B) "20 <t ₁ · A <40
(C) "20 <D ₂ · A <40
(D) "30 <(t ₁ + D ₂ ) · A <80
(E) ”30 <−f ₁₁ · A <55
(F) ”90 <f ₁₂ · A <110
(G) ”20 <f ₂₁ · A <40
(H) ”0.6 <Φ ₂₁ / Φ _w <0.8
(I) "19.5 <R ₂₁ · A <34
(J) ”75 <−f ₂₂ · A <140
(K) ”0.33 <−Φ ₂₂ / Φ _w <0.49
(L) "-1 <(R 21 + R 22) / (R 21 -R 22) <- 0.5
(M) "0.8 <(R ₂₃ + R ₂₄ ) / (R ₂₃ -R ₂₄ ) <2.5
(N) ”72 <ν _d21 <90
Next, another electronic imaging apparatus having the same object in the present invention will be described.

  Another electronic imaging apparatus according to the present invention includes, in order from the object side, a first lens group that includes a negative lens and a positive lens, and has a negative power as a whole, and an aperture stop, a positive lens, Consists of a second lens group consisting of two negative lenses and having a positive power as a whole. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is reduced. The first lens group has an aspherical surface, the second lens group has an aspherical surface on the most object side surface, and satisfies the following conditional expressions (1) and (2): In order from the zoom lens or the object side, the first lens unit having the negative lens on the most object side and the positive lens on the most image side and having a negative power as a whole, and the aperture stop, the positive lens, and the negative lens from the object side. The second len which consists of two pieces and has positive power as a whole And a third lens group consisting of one positive lens, and when zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is reduced, and the second lens The distance between the first lens group and the third lens group increases, the first lens group has an aspherical surface, the second lens group has an aspherical surface on the most object-side surface, and the second lens group The negative lens shape of the second type zoom lens satisfying the following conditional expression (1), or in order from the object side, the most object side is the negative lens and the most image side is the positive lens, and the negative power as a whole A first lens group having an aperture stop, a positive lens, and a negative lens from the object side, a second lens group having a positive power as a whole, and a third lens group having a single positive lens. The first lens group and the first lens group when zooming from the wide-angle end to the telephoto end. The distance between the lens groups is reduced, the distance between the second lens group and the third lens group is increased, the first lens group has an aspherical surface, and the second lens group is the most object-side surface. A third type of zoom lens that has an aspherical surface and satisfies the following conditional expression (2), or two negative lenses, two positive lenses, or a negative lens, a negative lens, and a positive lens in order from the object side. A first lens group consisting of three lenses and having a negative power as a whole, and a second lens group consisting of an aperture stop, a positive lens and a negative lens from the object side, and having a positive power as a whole. When zooming from the end to the telephoto end, the distance between the first lens group and the second lens group becomes small, the first lens group has an aspherical surface, and the second lens group has the most object side surface. A fourth surface satisfying the following conditional expressions (1) and (2) This is an electronic imaging device that employs any of the above zoom lenses.

  By adopting the configuration of the negative first lens group and the positive second lens group, it becomes easy to lengthen the back focus, and it becomes easy to take a space for arranging a low-pass filter or the like in front of the image plane. By providing an aperture stop that moves together with the second lens group on the most object side of the second lens group that is a variable power group, the effective diameter of the second lens group can be reduced, and thereby the thickness of the second lens group can also be reduced. Therefore, the thickness can be reduced. Chromatic aberration can be corrected and the thickness can be reduced by configuring the second lens group with two positive and negative lenses.

  Further, in the zoom lens employed in the electronic imaging apparatus of the present invention, the first lens group has an aspheric surface, and the second lens group has an aspheric surface on the most object side surface. The aspherical surface of the first lens group is effective for distortion, astigmatism and coma, and the aspherical surface closest to the object side of the second lens group is effective for correcting spherical aberration and coma. It should be noted that if an aspheric surface is also provided on the most image surface side of the second lens group, it is effective in correcting astigmatism.

  Hereinafter, conditions (1) and (2) will be described.

(1) 0.6 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.0
(2) 0.08 <t _2N / D ₂ <0.28
Where R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, R ₂₄ is a radius of curvature near the optical axis of the image side surface of the negative lens of the second lens group, and D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and t _2N is the image side of the positive lens of the second lens group. This is the distance on the optical axis from the surface to the image side surface of the second lens group.

  The negative lens of the second lens group has a meniscus shape having a concave surface on the image side, so that coma can be corrected well. However, if the curvature of the concave surface is too tight, the incident angle of the light beam on the image surface is reduced. Larger and more prone to shading problems. That is, when the upper limit of 3.0 of the condition (1) is exceeded, shading tends to occur, and when the lower limit of 0.6 is exceeded, correction of coma aberration tends to be insufficient.

  The following is more preferable.

(1) ′ 0.8 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <2.5
Furthermore, it is more preferable to do the following.

(1) "0.9 <(R ₂₃ + R ₂₄ ) / (R ₂₃ -R ₂₄ ) <2.0
Condition (2) defines the distance t _2N on the optical axis from the image-side surface of the positive lens of the second lens group to the image-side surface of the negative lens of the second lens group. Astigmatism cannot be corrected unless this part is thickened to some extent, but this is a problem for the purpose of reducing the thickness of each element of the optical system. Accordingly, astigmatism is corrected by introducing an aspheric surface on the image side surface of the negative lens. Nevertheless, if the lower limit of 0.08 is exceeded, astigmatism cannot be corrected. If the upper limit of 0.28 is exceeded, the thickness of the entire lens system is unacceptable.

  The following is more preferable.

(2) '0.1 <t _2N / D ₂ <0.25
Furthermore, it is more preferable to do the following.

(2) ”0.12 <t _2N / D ₂ <0.22
Further, instead of or in addition to the condition (2), at least one of the following conditional expressions (3) and (4) may be satisfied.

(3) 0.3 <D ₂ / f _W <1.5
(4) 0.24 <D ₂ /L<1.2
Where D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and f _W is the total system at the wide angle end. The focal length (when focusing on an object point at infinity), L is the diagonal length of the effective imaging area (substantially rectangular) of the electronic imaging device.

  If both the conditions (3) and (4) are smaller than the lower limit of 0.3 to 0.24, it is difficult to correct astigmatism. Since the margin is small, it is difficult to manufacture. When the upper limit of 1.5 to 1.2 is exceeded, the thickness when retracted becomes thick.

  In addition, it is more preferable if it is as follows individually or simultaneously.

(3) ′ 0.5 <D ₂ / f _W <1.4
(4) ′ 0.4 <D ₂ /L<1.12
Furthermore, it is more preferable to do the following.

(3) "0.7 <D ₂ / f _W <1.3
(4) "0.56 <D ₂ /L<1.04
Further, the refractive index n ₂₁ of the positive lens of the second lens group is preferably higher in order to reduce the size while improving the spherical aberration, coma aberration, and Petzval sum. (5) 1.6 <n ₂₁ <1.9
Is preferably satisfied.

  If the lower limit of 1.6 of this condition is exceeded, these aberrations tend to be undercorrected, and if corrected, downsizing becomes difficult. The upper limit of 1.9 is set because there is no glass material that can be practically used.

  The following is more preferable.

(5) ′ 1.65 <n ₂₁ <1.9
Furthermore, it is more preferable to do the following.

(5) "1.68 <n ₂₁ <1.9
Each of the second lens groups is composed of four refracting surfaces in contact with air. However, it is important that the shape of each refracting surface is appropriate in order to maintain a good aberration state with little aberration variation over the entire zoom range. . That is, it is preferable that the radii of curvature R ₂₁ , R ₂₂ , R ₂₃ , R _{24 in the} vicinity of the optical axis of each surface satisfy the following conditions individually or simultaneously in order from the object side.

(6) −1.5 <R ₂₁ / R ₂₂ <0.2
(7) -1.0 <R ₂₂ / R ₂₃ <0.5
(8) -0.3 <R ₂₄ / R ₂₃ <0.5
(9) 0.5 <R ₂₄ / R ₂₁ <2.0
When the upper limit of 0.2 in the condition (6) is exceeded, spherical aberration is likely to occur, and when the lower limit of −1.5 is exceeded, coma is likely to occur. As described above, since the negative lens of the second lens group has a meniscus shape having a concave surface on the image side, coma can be favorably corrected. If the upper limit values 0.5 and 0.5 of the conditions (7) and (8) are exceeded, the coma aberration tends to deteriorate, and if the lower limit value of -1.0 of the condition (7) is exceeded, spherical aberration occurs. If the lower limit of -0.3 of the condition (8) is exceeded, the incident angle of the light ray on the image plane becomes large, and the problem of shading tends to occur. The basic power of the second lens group is largely determined by R ₂₁ and R ₂₄ . Exceeding the lower limit of 0.5 for condition (9) is good for correcting spherical aberration, coma, etc., but is not preferable for miniaturization because the refractive power is weakened. When the upper limit of 2.0 is exceeded, correction of chromatic aberration is insufficient in addition to spherical aberration and coma. In addition, aberration stability over the entire zoom range is not good regardless of any of the above four conditions.

  In addition, it is more preferable if it is as follows individually or simultaneously.

(6) ′ − 1.2 <R ₂₁ / R ₂₂ <0
(7) ′ − 0.7 <R ₂₂ / R ₂₃ <0.35
(8) ′ − 0.2 <R ₂₄ / R ₂₃ <0.3
(9) ′ 0.7 <R ₂₄ / R ₂₁ <1.5
Furthermore, it is more preferable to do the following.

(6) ”−0.9 <R ₂₁ / R ₂₂ <−0.2
(7) "-0.5 <R ₂₂ / R ₂₃ <0.25
(8) "-0.15 <R ₂₄ / R ₂₃ <0.2
(9) "0.9 <R ₂₄ / R ₂₁ <1.2
In addition, when it has the 3rd lens group comprised by one positive lens as a zoom lens mounted in the electronic imaging device of this invention (the type of said 2nd and 3rd invention), when the following conditions are satisfy | filled It is effective.

The first is that each refracting surface is only a spherical surface or an aspherical surface with a small deviation amount that satisfies the following conditions only when the third lens group has a focusing function. (10) | abs (Z) | / L <1.5 × 10 ⁻²
Where L is the diagonal length of the effective imaging region of the electronic imaging device, and abs (Z) is the radius of curvature on the optical axis of each refractive surface of the third lens group at a position where the height from the optical axis is 0.35L. This is the amount of deviation in the optical axis direction from the spherical surface to the refractive surface.

  When this third lens group is used for focusing, aberration fluctuations become a problem, but if an amount of aspherical surface more than necessary enters the third lens group, the first lens group, Astigmatism remaining in the lens group is corrected by the third lens group. If the third lens group moves for focusing, the balance is lost, which is not preferable. Therefore, when focusing with the third lens group, astigmatism must be substantially eliminated over the entire zoom range with the first lens group and the second lens group. For this reason, the third lens group is constituted by a spherical system or a small amount of aspherical surface, and an aperture stop is arranged on the object side of the second lens group, and the most effective image in the second lens group, particularly for off-axis aberrations. The lens on the side should be aspheric. Further, in this type, since the front lens diameter is difficult to increase, the aperture stop is integrated with the second lens group (in the examples described later, it is disposed immediately before the second lens group and integrated with the second lens group). However, not only is the mechanism simple, but a dead space at the time of retraction does not easily occur, and the difference in F value between the wide-angle end and the telephoto end is small.

If the upper limit of 1.5 × 10 ⁻² of the condition (10) is exceeded, the astigmatism will be greatly lost if rear focusing is performed with the third lens group, which is not preferable.

  The following is more preferable.

(10) ′ | abs (Z) | / L <1.5 × 10 ⁻³
Furthermore, it is more preferable to do the following.

(10) "| abs (Z) | / L <1.5 × 10 ^-4
In addition, even when the rear focus is introduced while making the optical system thin, when considering the stabilization of each aberration such as astigmatism and chromatic aberration from infinity to a short distance in the entire zoom range, the third lens group satisfies the following conditions ( 11) may be satisfied.

(11) −2.0 <(R ₃₁ + R ₃₂ ) / (R ₃₁ −R ₃₂ ) <1.0
Here, R ₃₁ is a radius of curvature on the optical axis of the object side surface of the positive lens in the third lens group, and R ₃₂ is a radius of curvature on the optical axis of the image side surface of the positive lens in the third lens group.

  If the upper limit of 1.0 of the condition (11) is exceeded, the fluctuation of astigmatism due to the rear focus becomes too large, and even if the astigmatism can be corrected well at an infinite object point, Astigmatism tends to deteriorate. If the lower limit of −2.0 is exceeded, astigmatism fluctuations due to rear focus are small, but it is difficult to correct aberrations for infinite object points.

  The following is more preferable.

(11) ′ − 1.6 <(R ₃₁ + R ₃₂ ) / (R ₃₁ −R ₃₂ ) <0.7
Furthermore, it is more preferable to do the following.

(11) "-1.2 <(R ₃₁ + R ₃₂ ) / (R ₃₁ -R ₃₂ ) <0.4
Furthermore, when zooming from the wide-angle end to the telephoto end, if so zooming when the amount of movement of the third lens group x ₃ satisfies the following conditions, excellent stability of aberrations in the entire zoom range.

(12) −0.5 <x ₃ / √ (f _W · f _T ) <0.5
When the upper limit of 0.5 of the condition (12) is exceeded, the stability of aberrations such as spherical aberration, coma aberration, astigmatism, etc. in the entire zoom range deteriorates. If the lower limit of −0.5 is exceeded, the difference between the exit pupil position at the wide-angle end and the telephoto end becomes too large, and it becomes difficult to maintain good shading over the entire zoom range.

  The following is more preferable.

(12) ′ − 0.4 <x ₃ / √ (f _W · f _T ) <0.4
Furthermore, it is more preferable to do the following.

(12) "-0.3 <x ₃ / √ (f _W · f _T ) <0.3
Further, in order from the object side, there are a first lens group having a negative power and a second lens group having a positive power, and each surface on the optical axis is convex on the object side. A negative meniscus lens and a positive meniscus lens, and the object side surface of the positive meniscus lens is concave on the opposite side to the direction in which the center of curvature exists in the vicinity of the optical axis. Preferably, the electronic imaging apparatus includes a zoom lens that is an aspherical surface and an electronic imaging device disposed on the image plane side of the zoom lens.

  By using the aspheric surface described above, it is possible to share aberration correction between the on-axis light beam and the off-axis light beam at the wide-angle end. At this time, since the negative lens and the positive lens in the first lens group have their surfaces on the optical axis facing the object side, the bending angle of the light beam with respect to the axial light beam can be reduced. It is possible to satisfactorily correct on-axis aberrations up to.

  Further, in order from the object side, a negative lens having a first lens group having a negative power and a second lens group having a positive power, the first lens group having a concave surface facing the image surface side Each of the surfaces on the optical axis has a positive meniscus lens having a convex surface facing the object side, and the object side surface of the positive meniscus lens has an outermost peripheral portion of the refractive surface effective portion having a center of curvature near the optical axis. A zoom lens that is aspherical in a concave shape to the opposite side of the existing direction and that satisfies the following condition (A); and an electronic imaging device disposed on the image plane side of the zoom lens. It is preferable to configure the electronic imaging device as a feature.

(A) −5.0 <(R ₁₃ + R ₁₄ ) / (R ₁₃ −R ₁₄ ) <− 1.7
Where R ₁₃ is the radius of curvature of the object side surface of the positive meniscus lens of the first lens group, and R ₁₄ is the radius of curvature of the image side surface of the positive meniscus lens of the first lens group.

  By using the aspheric surface described above, it is possible to share aberration correction between the on-axis light beam and the off-axis light beam at the wide-angle end. In particular, by satisfying the above condition (A), on-axis or off-axis aberration correction at the wide-angle end can be performed satisfactorily. When the upper limit of -1.7 of the condition (A) is exceeded, the meniscus shape of the central portion of the positive lens becomes loose. On the other hand, when the lower limit of -5.0 is exceeded, the meniscus shape becomes too strong. It becomes difficult to correct aberrations off-axis. Furthermore, it is more preferable to replace the condition (A) with an electronic imaging apparatus that satisfies the following condition (A) ′.

(A) ′ − 5.0 <(R ₁₃ + R ₁₄ ) / (R ₁₃ −R ₁₄ ) <− 2.4
Even in such an optical system, it is possible to further reduce the size, increase the performance, and reduce the cost by satisfying a plurality of the above-described various conditions and configurations.

Further, regarding the variation of the exit pupil position, specifically, when the magnification is changed from the wide angle end to the telephoto end at the time of focusing on an object point at infinity, a change amount Δ (( 1 / EXP) [= | (1 / EXPT)-(1 / EXPW) |]
(13) Δ (1 / EXP) · √ (f _W · f _T ) <1
To be satisfied. However, EXPT is the exit pupil position at the telephoto end, and EXPW is the exit pupil position at the wide angle end.

  If the upper limit of 1 to condition (13) is exceeded, it will be difficult to maintain good shading over the entire zoom range.

  The following is more preferable.

(13) 'Δ (1 / EXP) · √ (f _W · f _T ) <0.8
Furthermore, it is more preferable to do the following.

(13) “Δ (1 / EXP) · √ (f _W · f _T ) <0.7
The above conditions (1) to (13) "are preferably used for an electronic imaging apparatus having a zoom lens with a zoom ratio of 2.4 or more or 2.8 or more.

Furthermore, when zooming from the wide-angle end to the telephoto end, the following conditions zooming when the amount of movement of the third lens group x ₃ is relative to the change amount x _2-3 of the second lens group and the air distance between the third lens group It is desirable to satisfy.

(B) 0.005 <| x ₃ / (γ × x _2-3 ) | <0.05
Where γ is the zoom ratio from the wide-angle end to the telephoto end.

  When the lower limit of 0.005 of the condition (B) is exceeded and the amount of movement of the third lens group during zooming is reduced, the effect of adjusting the exit pupil position is reduced. On the other hand, if the upper limit of 0.05 is exceeded, the amount of movement of the third lens group becomes large and the entire optical system becomes large.

Moreover,
(B) ′ 0.01 <| x ₃ / (γ × x _2-3 ) | <0.035
Then, the effect increases.

  Further, it is more preferable that the third lens group moves toward the image side at the telephoto end than at the wide angle end in order to make the optical system compact.

  What will be described below is that by adding as a condition to the zoom lens described so far, it is possible to make a small zoom lens with a small number of constituent elements with further improved aberration correction.

One,
By introducing aspherical surfaces on the most object-side surface and the most image-side surface of the first lens group, a wide-angle barrel distortion (especially one first lens group) is common in this type of zoom lens. Therefore, it can be corrected without deteriorating astigmatism, coma aberration and spherical aberration on the telephoto side. In particular, a double-sided aspheric surface is highly effective.

One,
By introducing an aspherical surface on the most object side surface and the most image side surface of the second lens group, spherical aberration, coma aberration, and astigmatism are kept good over the entire zoom range. Furthermore, it is preferable to add the condition (10) in order to keep the focus well in the entire area.

One,
By introducing aspherical surfaces on both sides of the positive lens in the first lens group, as in the case of this type of zoom lens, the wide-angle barrel distortion, which is common to this type of lens, is reduced in astigmatism, coma and telephoto spherical aberration. It can be corrected without doing.

One,
All the negative lenses of the first lens group and the second lens group have a meniscus shape having a convex surface on the object side. In the case of the first lens group, it is advantageous for coexistence of correction of barrel distortion on the wide angle side, astigmatism, coma aberration and spherical aberration on the telephoto side, and in the case of the second lens group, spherical aberration over the entire zoom range. Further, correction of coma and astigmatism correction is advantageous.

One,
The object side surface of the positive lens in the second lens group is a strong convex surface. By making the positive lens of the second lens group into a shape having a strong convex surface on the object side, it is easy to achieve both reduction in size and correction of coma aberration.

One,
By satisfying the following conditions with respect to the radius of curvature near the optical axis of the object side surface of the negative lens in the first lens group, the barrel distortion on the wide-angle side that is common in this type of zoom lens is reduced as described above. Astigmatism, coma, and spherical aberration on the telephoto side can be corrected without deteriorating. Even better if an aspheric surface is introduced.

(14) −0.3 <f _W / R ₁₁ <0.4
Where R ₁₁ is the radius of curvature near the optical axis (on the optical axis) of the first lens surface from the object side of the first lens group, and f _W is the focal length of the entire system at the wide angle end (when focusing on an object point at infinity) ).

  If the upper limit of 0.4 of the condition (14) is exceeded, it is difficult to correct astigmatism and spherical aberration on the telephoto side, and if the lower limit of −0.3 is exceeded, the barrel distortion at the wide angle end Correction becomes difficult. In addition, it is preferable to correct distortion by introducing an aspheric surface into the first lens group, and correct astigmatism with the remaining spherical component. If the upper limit is exceeded, it will be disadvantageous for correction of astigmatism and spherical aberration on the telephoto side, and if it exceeds the lower limit, distortion will not be corrected even with an aspherical surface.

  The following is more preferable.

(14) '−0.2 <f _W / R ₁₁ <0.30
Furthermore, it is more preferable to do the following.

(14) "-0.15 <f _W / R ₁₁ <0.25
One,
By making the air space on the optical axis in contact with the object side of the positive lens of the first lens group satisfy the following conditions, the first lens group itself is thinned in the optical axis direction, but distortion and astigmatism are reduced. It is possible to achieve both aberration correction.

(15) 0.3 <d _NP / f _W <1
Here, d _NP is an air interval on the optical axis that is in contact with the object side of the positive lens of the first lens group.

  If the upper limit of 1 of the condition (15) is exceeded, it will be advantageous for correcting astigmatism, but the thickness of the first lens group will increase and it will be contrary to miniaturization. When the lower limit of 0.3 is exceeded, it is difficult to correct astigmatism.

  The following is more preferable.

(15) '0.4 <d _NP / f _W <0.9
Furthermore, it is more preferable to do the following.

(15) “0.5 <d _NP / f _W <0.8
Alternatively, d _NP may be defined by the focal length f ₁ of the first lens group to satisfy any of the following conditions (15) ^* and (15) ^** .

(15) ^* 1 <| d _NP / f ₁ | <3
(15) ^** 1.5 <| d _NP / f ₁ | <2.5
One,
By making the thickness of the first lens group from the lens surface closest to the object side to the lens surface closest to the image side satisfy the following conditions, various specifications and performance of the zoom lens system are small and thin. Can be established on

(16) 0.4 <t ₁ /L<2.2
Here, t ₁ is the thickness on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the first lens group, and L is the diagonal length of the effective imaging region (substantially rectangular) of the electronic imaging device. .

  If the upper limit of 2.2 of this condition (16) is exceeded, thinning tends to be hindered. If the lower limit of 0.4 is exceeded, the radius of curvature of each lens surface must be relaxed, and the paraxial It becomes difficult to establish the relationship and correct various aberrations.

  This condition range needs to be changed depending on the value of L in order to secure the marginal wall and mechanical space.

(16) '0.6 <t ₁ /L<2.2 (when L <6.2 mm) 0.5 <t ₁ /L<2.0 (however, 6.2 mm <L <9. 2mm)
0.4 <t ₁ /L<1.8 (when 9.2 mm <L)
One,
At least one of the aspheric surfaces to be introduced into the first lens group is a surface having a concave shape on the opposite side to the direction in which the center of curvature exists in the vicinity of the optical axis in the refracting surface effective part ( That is, in the cross section including the optical axis, the cross-sectional shape is a surface having a primary inflection point in the effective portion), so that even if the number of negative lenses in the first lens group is one, In addition to barrel distortion, astigmatism, coma and telephoto spherical aberration can be compatible. Furthermore, it is more preferable that the surface includes a region where the normal of the surface is parallel to the optical axis in the effective surface outside the optical axis.

One,
At least two of the aspheric surfaces to be introduced into the first lens group are surfaces having a concave shape on the opposite side to the direction in which the center of curvature exists in the vicinity of the optical axis at the outermost peripheral portion of the refractive surface effective portion. As a result, even if the number of negative lenses in the first lens group is one, it becomes easier to achieve coexistence of barrel aberration on the wide angle side, astigmatism, coma aberration and spherical aberration on the telephoto side. . Further, it is more preferable that the two surfaces include a region in which the normal of the surface is parallel to the optical axis in the effective surface outside the optical axis.

One,
The following conditions should be satisfied.

(17) -1 <f ₁ / R ₁₁ <0.5
Here, f ₁ is the focal length of the first lens group, and R ₁₁ is the radius of curvature in the vicinity of the optical axis (on the optical axis) of the most object side surface of the first lens group.

  When the upper limit of 0.5 of the condition (17) is exceeded, even if a refractive surface having an extreme value other than on the optical axis in the effective range is introduced, even if it does not become barrel-shaped distortion, distortion of a complicated shape Or adversely affect other off-axis aberrations. When the lower limit of -1 is exceeded, the introduction effect is small.

  The following is more preferable.

(17) '-0.8 <f ₁ / R ₁₁ <0.3
Furthermore, it is more preferable to do the following.

(17) “−0.7 <f ₁ / R ₁₁ <0.2
One,
The positive lens in the first lens group has a portion in which the radius of curvature in the vicinity of the double-sided optical axis is a positive value and the object side has a concave shape at the periphery in the optical effective range of each surface. In this case, even if the number of negative lenses in the first lens group is one, it is possible to satisfy both astigmatism, coma aberration and spherical aberration on the telephoto side, including barrel distortion on the wide angle side.

  Furthermore, the following conditions should be satisfied.

(18) −2.5 <f ₁ / R ₁₃ <−0.5
(19) -1.5 <f ₁ / R ₁₄ <0.5
Where f ₁ is the focal length of the first lens group, R ₁₃ is the radius of curvature of the object side surface of the positive lens of the first lens group, and R ₁₄ is the radius of curvature of the image side surface of the positive lens of the first lens group. is there.

  If the lower limit values of -2.5 and -1.5 are exceeded in these conditions (18) and (19), respectively, even if a refractive surface having an extreme value other than on the optical axis is introduced in the effective range, the barrel shape Even if it does not become distorted, it becomes a distortion of a complicated shape, or adversely affects other off-axis aberrations. When the upper limit is exceeded by −0.5 and 0.5, the introduction effect is small.

  The following is more preferable.

(18) '−2.0 <f ₁ / R ₁₃ <−0.6
(19) '-1.2 <f ₁ / R ₁₄ <0.2
Furthermore, it is more preferable to do the following.

(18) "-1.7 <f ₁ / R ₁₃ <-0.7
(19) "-1 <f ₁ / R ₁₄ <0
In the case of the zoom lens of the present invention described above, when focusing on a short-distance object, it is preferable to extend the first lens group to the object side along the optical axis.

  In order to use the zoom lens described above for an electronic imaging apparatus, it is desirable to satisfy the conditions described below.

  First of all, regarding the specifications, the appropriate ranges of the wide angle end half field angle, the telephoto end open F value, and the zoom ratio γ are shown under the following conditions.

(20) 28 ° <ω _W <40 °
(21) 2.7 <F _T <5
(22) 2 <γ <4
However, ω _W is the half angle of view at the wide-angle end. _FT is the open F value at the telephoto end. γ is a zoom ratio.

  If the condition (20) exceeds the upper limit of 40 °, it is difficult to correct off-axis aberrations, and the diameter and thickness must be increased, which is contrary to miniaturization. Exceeding the lower limit of 28 ° is insufficient as a wide-angle end angle of view for general use. In the present invention, the angle of view in this range is sufficiently supported.

  If the condition (21) exceeds the lower limit of 2.7, it is difficult to correct axial aberrations, and the diameter and thickness must be increased, which is contrary to miniaturization. If the upper limit of 5 is exceeded, the F value for general use is insufficient. In particular, when considering application to a small imager size, problems of diffraction and sensitivity are likely to occur.

  If the condition (22) exceeds the upper limit of 4, Seidel aberrations and chromatic aberration cannot be corrected. If the lower limit of 2 is exceeded, the method of trimming an image with a single-focus lens having a large number of pixels is cheaper and easier to achieve high image quality, which is meaningless.

Next, mention will be made of thinning the filters. In an electronic imaging device, an infrared absorption filter having a certain thickness is inserted closer to the object side than the imaging element so that normally infrared light does not enter the imaging surface. Consider replacing this with a thin coating. Naturally, it will be thinner, but it has a side effect. If a near-infrared sharp cut coat having a transmittance of 80% or more at 600 nm and a transmittance of 10% or less at 700 nm is introduced closer to the object side than the image pickup device behind the zoom lens system, it is more than the absorption type. The transmittance on the red side becomes relatively high, and the magenta tendency on the bluish purple side, which is a defect of the CCD having the complementary color mosaic filter, is alleviated by gain adjustment, and color reproduction similar to that of the CCD having the primary color filter can be obtained. On the other hand, in the case of a complementary color filter, since the transmitted light energy is high, the sensitivity is substantially higher than that of a CCD with a primary color filter and it is advantageous in terms of resolution. is there. Also for the optical low-pass filter as the other filter, the total thickness t _LPF may satisfy the following conditions.

(23) 0.15a <t _LPF <0.5a [mm]
Here, a is the horizontal pixel pitch (unit: μm) of the electronic image sensor.

  Although it is effective to reduce the optical low-pass filter to reduce the collapsed thickness, it is generally not preferable because the moire suppressing effect is reduced. On the other hand, as the pixel pitch decreases, the contrast of the frequency component above the Nyquist limit decreases due to the diffraction effect of the imaging lens system, and a decrease in the moire suppression effect is allowed to some extent. For example, when three types of filters having crystal axes in the horizontal (= 0 °) and ± 45 ° directions are projected in the direction of the optical axis when projected on the image plane, the effect of suppressing moiré is considerably improved. It has been known. As a specification in which the filter is the thinnest in this case, it is known that the filter is shifted by SQRT (1/2) * a μm horizontally by aμm and ± 45 °. Here, SQRT is a square route and means a square root. The filter thickness at this time is approximately [1 + 2 * SQRT (1/2)] * a / 5.88 (mm).

  This is a specification that makes the contrast zero at a frequency corresponding to the Nyquist limit. If it is made thinner by several percent to several tens of percent than this, a slight contrast of the frequency corresponding to the Nyquist limit appears, but it can be suppressed by the influence of the diffraction. It is preferable to satisfy the condition (23) including filter specifications other than those described above, for example, when two sheets are stacked or one sheet is used. If the upper limit of 0.5a is exceeded, the optical low-pass filter is too thick and hinders thinning. When the lower limit of 0.15a is exceeded, moire removal becomes insufficient. However, the condition of a in carrying out this is 5 μm or less.

If a is 4 μm or less, it is more susceptible to diffraction,
(23) '0.13a <t _LPF <0.5a [mm]
It is good. The following may also be used.

(23) "
When a is 4 μm or more:
0.3a <t _LPF <0.5a [mm]
(However, when three filters are stacked and a <5 μm)
0.2a <t _LPF <0.28a [mm]
(However, when two filters are stacked and a <5 μm)
0.1a <t _LPF <0.16a [mm]
(However, when there is one filter and a <5 μm)
When a is 4 μm or less:
0.25a <t _LPF <0.5a [mm]
(However, when three filters are stacked)
0.16a <t _LPF <0.25a [mm]
(However, when two filters are stacked)
0.08a <t _LPF <0.14a [mm]
(However, when there is one filter)
When an image sensor with a small pixel pitch is used, the image quality deteriorates due to the diffraction effect due to narrowing down. Therefore, there are a plurality of apertures with a fixed aperture size, and one of them is any of the most image side lens surface of the first lens group and the most object side lens surface of the third lens group. The electronic imaging device can be inserted into the optical path and can be exchanged with another device, and the image plane illuminance can be adjusted. It is preferable to adjust the amount of light so as to have media having different transmittances to each other and less than 80%. Alternatively, when adjustment is performed so that the amount of light corresponds to the F value such that a (μm) / F number <0.4, the medium having different transmittances for 550 nm and less than 80% in the aperture An electronic imaging device having For example, if the medium is not within the range of the above condition from the open value, or a dummy medium with a transmittance of 550 nm or more is set to 91% or more, and if within the range, the aperture stop diameter is reduced to such an extent that diffraction is affected. It is better to adjust the amount of light with something like an ND filter.

  Alternatively, the plurality of openings may be arranged such that their diameters are reduced in inverse proportion to the F value, and optical low-pass filters having different frequency characteristics may be placed in the openings instead of the ND filters. Since the diffraction degradation increases as the aperture is narrowed down, the frequency characteristic of the optical low-pass filter is set higher as the aperture diameter decreases.

  As described above, another object of the present invention is to provide an electronic imaging apparatus that can adjust the light amount while suppressing the influence of diffraction while maintaining high image quality, and can also shorten the overall length of the zoom lens. That is. A configuration for this will be described below.

The first configuration is a zoom lens having a plurality of lens groups that change their respective distances to change the focal length, an aperture stop that is arranged in the optical path and restricts at least the axial beam diameter, and an image thereof In an electronic imaging device comprising an electronic imaging device arranged on the side,
The aperture stop has a fixed aperture shape, and an electronic image pickup comprising a filter for adjusting the amount of light by changing the transmittance on the optical axis in a space different from the space where the aperture stop is disposed Device.

  According to such a configuration, the amount of light is adjusted by changing the transmittance of the filter, and by fixing the aperture shape, deterioration of the electronic image due to diffracted light that occurs when the aperture diameter is reduced can be suppressed.

  Further, in the conventional mechanism for adjusting the light amount at the aperture position, the mechanism for adjusting the light amount, such as making the aperture shape variable, has been a cause of hindering the degree of freedom of arrangement of the optical system. Since the aperture shape is fixed, the thickness of the aperture mechanism itself can be reduced. Accordingly, the distance between the lenses sandwiching the stop can be made shorter than before, and the overall length of the lens can be shortened.

  The aperture stop may be located in the group, that is, between lenses having a constant interval during zooming.

  Further, the aperture stop does not necessarily have to be circular. However, in the conventional variable aperture, a large number of aperture plates are used in order to always have a circular aperture shape. In the present invention, since the aperture shape is a circular aperture, a so-called beautiful blur that suppresses unevenness in the image of the out-of-focus portion can be obtained with a simple configuration regardless of the light amount adjustment state. preferable.

  Further, the principal ray of the off-axis light beam determined by the aperture stop may be vignetted at other parts. That is, in general, the light amount adjusting means of the type that reduces the area of the aperture stop has to be arranged at a position where the light amount at the periphery of the screen when the aperture is reduced is not extremely reduced. However, since this is not necessary in the present invention, the degree of freedom in design can be increased.

  Further, regarding the aperture stop having a fixed shape, an electronic image with high resolution can be obtained by adopting the following shape.

That is, in the second configuration, in the first configuration, the open F number F at the telephoto end is smaller than the minimum pixel pitch a (unit: mm) of the electronic image sensor.
When 1.5 × 10 ³ × a / 1 mm <F,
The length of the aperture stop in the vertical or horizontal direction of the imaging surface is longer than the length of the aperture stop in the diagonal direction of the imaging surface, or
The open F number F at the telephoto end is smaller than the minimum pixel pitch a (unit: mm) of the electronic image sensor.
When 1.5 × 10 ³ × a / 1 mm> F,
In the electronic imaging device, the length of the aperture stop in the vertical direction or the horizontal direction of the imaging surface is shorter than the length of the aperture stop in the diagonal direction of the imaging surface.

  For example, when the pixel pitch is in the first half of 2 μm, the F number is about 5.6 and the diffraction limit is reached. In the present invention, since the shape of the diaphragm is always fixed, the resolution can be increased by arbitrarily determining the aperture shape.

  The Rayleigh limit frequency is approximately 1 / (1.22Fλ), where F is the imaging lens used and F is the wavelength of the light used.

  On the other hand, the resolution limit of an image sensor having a plurality of pixels is represented by 1 / (2a) (a is a pixel pitch: all units are mm).

Therefore, in order to prevent the Rayleigh limit frequency from becoming smaller than the resolution limit of the image sensor,
1.22Fλ <2a
That means
F <1.64a / λ
Is a condition.

Here, in consideration of photographing with visible light, assuming that the wavelength used is λ = 546 (nm),
F <1.5 × 10 ³ × a / 1mm
Is a conditional expression of the theoretical limit of the F value.

Since it is effective to improve the image quality to improve the frequency characteristics in the horizontal and vertical directions, the open F value is
When 1.5 × 10 ³ × a / 1 mm <F,
To be less susceptible to diffraction,
It is preferable that the length of the aperture stop in the vertical direction or the horizontal direction of the imaging surface is longer than the length of the aperture stop in the diagonal direction of the imaging surface.

On the other hand, the open F value is
When 1.5 × 10 ³ × a / 1 mm> F,
To be less affected by geometric optical aberrations,
It is preferable that the length of the aperture stop in the vertical direction or the horizontal direction of the imaging surface is shorter than the length of the aperture stop in the diagonal direction of the imaging surface.

  Furthermore, it is possible to increase the cutoff frequency of the low-pass filter that has been used conventionally, or to eliminate the low-pass filter itself.

  Further, in order to shorten the overall length of the lens, the third configuration is the smallest of the variable air intervals in the zoom lens or the longest of the constant air intervals in the first configuration. The electronic imaging apparatus is characterized in that the filter is arranged in an air interval.

  With such a configuration, it is possible to arrange a filter at a place where a wide interval is always secured in the zooming range. This is advantageous for shortening the overall lens length.

  The same applies to the case where a shutter is provided, as will be described later.

  In addition, since the aperture shape is fixed, if the aperture shape is set large in order to ensure the amount of light, vignetting of the light beam caused by the lens barrel or the like occurs. Therefore, unevenness in brightness may occur between the center portion and the peripheral portion of the image.

  Therefore, in order to suppress unevenness in brightness with a filter that adjusts the amount of light, the fourth configuration is the first configuration. In the first configuration, the filter that adjusts the amount of light is transmitted at the peripheral portion with respect to the transmittance at the central portion. An electronic imaging device having at least one transmission surface with a high rate.

  By adopting such a configuration, it is possible to perform shooting with reduced brightness unevenness.

  Further, in order to reduce a ghost caused by reflected light of the filter, the fifth configuration is an electronic imaging characterized in that, in the first configuration, the filter for adjusting the light amount can be arranged to be inclined with respect to the optical axis. Device.

  According to a sixth configuration of the present invention, in the first configuration, the aperture stop is disposed between front and rear lens groups that sandwich a variable air interval at the time of zooming or focusing. The electronic image pickup apparatus is characterized in that the filter for adjusting the light amount is arranged at a position different from the air interval.

  By adopting such a configuration, the amount of movement of the lens group at the time of zooming can be increased, so that high zooming becomes easy.

  According to a seventh configuration of the present invention, in the first to sixth configurations, the aperture stop has a lens medium in the lens group at a position where a perpendicular line extending from the aperture stop to the optical axis and the optical axis intersect. It is an electronic imaging device characterized by being located inside.

  Since the aperture shape of the aperture stop does not change, such a configuration is possible. With this configuration, further miniaturization can be achieved.

  An eighth configuration of the present invention is the electronic imaging device according to the seventh configuration, wherein the aperture stop is provided in contact with any lens surface in the lens group.

  With this configuration, it is possible to increase the accuracy because the diaphragm position adjustment is unnecessary. In particular, if the lens surface is blacked with a diaphragm, the configuration can be simplified.

  According to a ninth configuration of the present invention, in the first to eighth configurations, the aperture stop is an aperture plate having an aperture on the optical axis side.

  In this way, the diaphragm thickness can be reduced.

  According to a tenth configuration of the present invention, in the first to ninth configurations, the zoom lens has at least a negative refractive power lens group, and a positive refractive power lens group disposed immediately after the image side. The distance between the lens unit having the negative refractive power and the lens unit having the positive refractive power is reduced at the telephoto end rather than the wide-angle end, and the aperture stop is made the most of the lens unit having the negative refractive power. The electronic imaging apparatus is characterized in that a filter for adjusting the light amount is disposed on the image plane side with respect to the aperture stop, and is disposed between the image side surface and the image side surface of the lens unit having the positive refractive power.

  If the zoom lens includes a configuration in which the negative lens group and the positive lens group are arranged in this order, the configuration in which the aperture stop is arranged at the above position makes the entire zoom lens compact and the angle of view at the wide-angle end. Can be secured easily.

  In addition, if an aperture stop is arranged at such a position, the spread of the light beam on the image side does not become too large. Therefore, if a filter for adjusting the amount of light is arranged at the above position, the filter itself can be made compact. This is advantageous for downsizing.

  More specifically, the eleventh configuration of the present invention is an electronic imaging apparatus characterized in that, in the tenth configuration, the negative lens group is disposed closest to the object side.

  With such a configuration, at least one of the effects of widening the angle of view, increasing the zoom ratio, and reducing the overall length can be achieved.

  Further, a twelfth configuration of the present invention is the zoom lens according to the tenth configuration, wherein the zoom lens includes, in order from the object side, a lens group having the negative refractive power and a lens group having the positive refractive power. The electronic imaging apparatus is characterized in that there are only two lens groups, the lens group having negative refractive power and the lens group having positive refractive power, which are movable when zooming.

  Such a configuration has at least one of the effects of increasing the wide angle of view and zoom ratio and shortening the overall length.

  Furthermore, the 13th structure of this invention is a 10th structure. WHEREIN: The said zoom lens is a lens group which has the said negative refracting power, and the lens group which has the said positive refracting power in order from an object side. An electronic imaging apparatus characterized by only two lens groups.

  With such a configuration, the configuration can be further simplified.

  A fourteenth configuration of the present invention is the electronic imaging apparatus according to the tenth to thirteenth configurations, wherein the aperture stop is arranged in an air space immediately before the lens unit having the positive refractive power. is there.

  With such a configuration, it is possible to make the light incident on the electronic image sensor closer to being perpendicular to the imaging surface.

  In particular, when the zoom lens is configured in the order of the negative lens group and the positive lens group from the object side, the negative lens group as the first lens group can be brought closer to the second lens group at the telephoto end. . Thereby, the overall length of the zoom lens can be shortened more than the amount of reduction in the distance between the first lens group and the second lens group.

  Further, if the lens unit having a positive refractive power and the aperture stop are moved together, the lens frame configuration can be simplified.

  According to a fifteenth configuration of the present invention, in the tenth to fourteenth configurations, the filter for adjusting the light amount is arranged in an air space immediately after the lens unit having the positive refractive power. An electronic imaging device.

  Such a configuration is more preferable because the filter can be arranged at a position where the light flux does not spread so much. In particular, when a two-group zoom lens including a negative lens group and a positive lens group is used, the beam bundle is not so wide, which is preferable.

  A sixteenth configuration of the present invention is the first to fifteenth configuration, wherein the distance on the optical axis between the aperture stop and the entrance surface of the filter that performs the light amount adjustment on the image side is α, The electronic imaging apparatus is characterized in that the following condition is always satisfied, where β is the distance on the optical axis between the incident surface of the filter for adjusting the light amount and the imaging surface of the electronic imaging element.

(24) 0.01 <α / β <1.0
It is more preferable to dispose the filter close to the aperture stop because the size of the filter itself can be reduced. When the upper limit of 1.0 of this condition is exceeded, it is difficult to make the filter small. On the other hand, if the lower limit of 0.01 is exceeded, the aperture and the filter will be too close, making it difficult to make the entire zoom lens compact.

  In this conditional expression, it is more preferable that the lower limit value is 0.1, and further 0.2. Moreover, it is more preferable to set the upper limit value to 0.8, further 0.6, and further 0.4.

  In addition, it is desirable that this conditional expression is satisfied in the entire zooming range. Alternatively, it is desirable to satisfy the condition that the stop is located closest to the image side in the zooming range.

  According to a seventeenth configuration of the present invention, in the first to sixteenth configurations, the maximum aperture diameter (diameter) of the aperture stop aperture is φα, and the maximum effective diameter (diagonal length) of the filter that performs the light amount adjustment is as follows. Is an electronic imaging device characterized by satisfying the following condition when .phi..beta.

(25) 0.5 <φβ / φα <1.5
If the lower limit of 0.5 of this conditional expression is exceeded, the possibility of vignetting of the light beam used for imaging increases. On the other hand, if the upper limit of 1.5 is exceeded, the filter becomes large.

  In this conditional expression, it is more preferable to set the lower limit value to 0.7, and further to 0.8. Moreover, it is more preferable that the upper limit value is 1.2, more preferably 1.05.

  It is desirable that this conditional expression is satisfied in the entire zoom range. Alternatively, it is desirable to satisfy the condition that the stop is located closest to the image side in the zooming range.

  According to an eighteenth configuration of the present invention, in the first to seventeenth configurations, the aperture stop is arranged at a variable interval, and both the lens surface immediately before and the lens surface immediately after the aperture stop have concave surfaces on the image side. In the electronic imaging apparatus, the outer shape of the aperture stop is a funnel shape that is inclined toward the image side as the distance from the optical axis increases.

  In this configuration, since the outer shape of the diaphragm is along the shape of the front and rear lens surfaces, it becomes easier to bring the front and rear lens surfaces closer to each other. Of course, this concept also includes the lens surface with the aperture outline painted black.

  The nineteenth configuration of the present invention is the electronic imaging apparatus according to any one of the first to eighteenth configurations, wherein the filter for adjusting the light amount is configured to be detachable in an optical path.

  According to a twentieth configuration of the present invention, in the nineteenth configuration, the filter for adjusting the amount of light swings in a direction in which a surface approaches parallel to the optical axis when retracting from the optical axis. An electronic imaging device.

  With this configuration, the space for retracting the filter around the zoom lens need not be increased in the direction away from the optical axis, and the size can be reduced.

  As described above, the filter for adjusting the amount of light has been mainly described as the first to twentieth configurations of the present invention. However, there are cases where a conventional variable aperture has a role of a shutter. Therefore, it is preferable to provide a shutter near the filter instead of or in addition to the filter. Alternatively, it is possible to arrange the filter and its shutter in another space with at least one lens interposed therebetween.

  For example, it can be configured as the following twenty-first to thirty-fourth configurations. The operation of these configurations can be understood by replacing the above-described filter with a shutter.

That is, the twenty-first configuration of the present invention is a zoom lens having a plurality of lens groups that change the focal length and change the focal length, and an aperture stop that is arranged in the optical path and restricts at least the axial beam diameter, And in an electronic imaging device provided with an electronic imaging device arranged on the image side,
In the electronic imaging apparatus, the aperture stop has a fixed aperture shape, and a shutter is disposed on an optical axis in a space different from the space in which the aperture stop is disposed.

  According to a twenty-second configuration of the present invention, in the twenty-first configuration, the aperture stop is disposed between front and rear lens groups that sandwich a variable air interval at the time of zooming or focusing operation. The electronic imaging apparatus is arranged at a position different from the air interval.

  According to a twenty-third configuration of the present invention, in the twenty-first or twenty-second configuration, the aperture stop has a position where a perpendicular line extending from the aperture stop to the optical axis and the optical axis intersect in the lens medium in the lens group. The electronic imaging device is characterized by being positioned.

  A twenty-fourth configuration of the present invention is the electronic imaging apparatus according to the twenty-third configuration, wherein the aperture stop is provided in contact with any lens surface in the lens group.

  According to a twenty-fifth configuration of the present invention, in the twenty-first to twenty-fourth configurations, the aperture stop is an aperture plate having an aperture on the optical axis side.

  According to a twenty-sixth configuration of the present invention, in the twenty-first to twenty-fifth configurations, the zoom lens has at least a lens unit having a negative refractive power and a lens group having a positive refractive power arranged immediately after the image side. The distance between the lens unit having the negative refractive power and the lens unit having the positive refractive power is reduced at the telephoto end rather than the wide-angle end, and the aperture stop is moved to the most image side surface of the lens group having the negative refractive power. To an image side surface of the lens unit having the positive refractive power, and the shutter is arranged on the image surface side with respect to the aperture stop.

  A twenty-seventh configuration of the present invention is an electronic imaging apparatus according to the twenty-sixth configuration, wherein the negative lens group is disposed closest to the object side.

  According to a twenty-eighth configuration of the present invention, in the twenty-sixth configuration, the zoom lens includes, in order from the object side, a lens group having the negative refractive power and a lens group having the positive refractive power, The electronic imaging apparatus is characterized in that the lens group movable at the time of zooming is only two lens groups, that is, the lens group having the negative refractive power and the lens group having the positive refractive power.

  According to a twenty-ninth configuration of the present invention, in the twenty-sixth configuration, the zoom lens includes, in order from the object side, two lenses of a lens group having the negative refractive power and a lens group having the positive refractive power. It is an electronic imaging device characterized by being only a group.

  A thirtieth aspect of the present invention is the electronic imaging apparatus according to any of the twenty-sixth to the twenty-ninth aspects, wherein the aperture stop is disposed in an air space immediately before the lens unit having the positive refractive power.

  A thirty-first configuration of the present invention is the electronic imaging device according to any of the twenty-sixth to thirtieth configurations, wherein the shutter is disposed in an air space immediately after the positive refractive power lens group.

  According to a thirty-second configuration of the present invention, in the twenty-first to thirty-first configurations, the distance on the optical axis between the aperture stop and the shutter closer to the image side is α ′, and imaging with the shutter and the electronic image sensor is performed. The electronic imaging apparatus is characterized in that the following condition is always satisfied when the distance on the optical axis to the surface is β ′.

(26) 0.01 <α ′ / β ′ <1.0
In this conditional expression, the lower limit value is more preferably 0.1, and further preferably 0.2. Moreover, it is more preferable that the upper limit value is 0.8, further 0.6, and further 0.4.

  It is desirable that this conditional expression is satisfied in the entire zoom range. Alternatively, it is desirable to satisfy the condition that the stop is located closest to the image side in the zooming range.

  According to a thirty-third configuration of the present invention, in the twenty-first to thirty-second configurations, the maximum aperture diameter (diameter) of the aperture stop aperture is φα, and the maximum effective diameter (diagonal length) of the shutter is φβ ′. Furthermore, the electronic imaging apparatus is characterized by satisfying the following conditions.

(27) 0.5 <φβ ′ / φα <1.5
In this conditional expression, it is more preferable to set the lower limit value to 0.7, and further to 0.8. Moreover, it is more preferable that the upper limit value is 1.2, more preferably 1.05.

  It is desirable that this conditional expression is satisfied in the entire zoom range. Alternatively, it is desirable to satisfy the condition that the stop is located closest to the image side in the zooming range.

  According to a thirty-fourth configuration of the present invention, in the twenty-first to thirty-third configurations, the aperture stop is arranged at a variable interval, and both the lens surface immediately before and the lens surface immediately after the aperture stop have a concave surface facing the image side, In the electronic imaging device, the outer shape of the aperture stop has a funnel shape that is inclined toward the image side as the distance from the optical axis increases.

  A numerical example related to the invention of the above-described fixed aperture corresponds to Example 12 described later.

Regarding the shape of the fixed diaphragm,
If the actual open F number is more than 4 times the brightness of the Rayleigh limit, for example,
A generally square near zero azimuth (generally the shape with the shortest horizontal or vertical dimension),
When the actual open F number is less than 4 times the brightness of the Rayleigh limit, for example,
An approximately square shape with an azimuth angle of 45 ° (generally the shape with the longest horizontal or vertical dimension),
It is good. This is because it is advantageous for the resolution in the horizontal and vertical directions.

  In addition, it is desirable that the above-described conditional expression between the diaphragm and the filter or the conditional expression between the diaphragm and the shutter is satisfied in the entire zooming range. Alternatively, it is desirable to satisfy the condition that the stop is located closest to the image side in the zooming range.

  According to the present invention, it is possible to obtain a zoom lens having a small retractable thickness, an excellent storage property, a high magnification, and an excellent imaging performance even in a rear focus, and a thinning of a video camera or a digital camera is achieved. Is possible.

Examples 1 to 12 of the zoom lens used in the electronic image pickup apparatus of the present invention will be described below. Examples 3 and 6 to 12 are reference examples. FIGS. 1 to 12 show lens cross-sectional views at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) at the time of focusing on an object point at infinity, respectively. In each figure, the first group is G1, the second group is G2, the third group is G3, a three-layer optical low-pass filter with a near-infrared cut coat on the first surface (surface on the object side). An optical low-pass filter provided is F, a cover glass of a CCD which is an electronic image pickup device is indicated by C, and an image plane of the CCD is indicated by I. The optical low-pass filter F and the cover glass are arranged in order from the object side. C is fixedly disposed between the second group G2 or the third group G3 and the image plane I.

  As shown in FIG. 1, the zoom lens according to the first exemplary embodiment includes a first group G1 having a negative refractive power, a second group G2 having a positive refractive power, and a third group G3 having a positive refractive power. Sometimes, when zooming from the wide-angle end to the telephoto end, the first lens unit G1 once moves to the image plane side and then reverses and moves to the object side. At the telephoto end, the first group G1 is slightly closer to the object side than the intermediate position. The second group G2 moves toward the object side, the interval between the first group G1 and the second group G2 becomes small, and the third group G3 moves slightly toward the image plane side.

  The first group G1 of the first embodiment includes two negative meniscus lenses having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side. The second group G2 is disposed after the stop. The third biconvex lens and a negative meniscus lens having a convex surface facing the object side, and the third group G3 includes one positive meniscus lens having a convex surface facing the object side. The aspherical surfaces are the image side surface of the negative meniscus lens on the object side of the first group G1, the object side surface of the biconvex lens of the second group G2, and the image side surface of the negative meniscus lens of the second group G2. Used on three sides.

  As shown in FIG. 2, the zoom lens according to the second exemplary embodiment includes a first group G1 having a negative refractive power, a second group G2 having a positive refractive power, and a third group G3 having a positive refractive power. Sometimes, when zooming from the wide-angle end to the telephoto end, the first lens group G1 once moves to the image plane side and then reverses and moves to the object side. At the telephoto end, the first group G1 is slightly closer to the object side than the intermediate position. The second group G2 moves toward the object side, the interval between the first group G1 and the second group G2 becomes small, and the third group G3 moves slightly toward the image plane side.

  The first group G1 of Example 2 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and the second group G2 is disposed after the stop. It consists of a biconvex lens and a biconcave lens, and the third group G3 consists of a single biconvex lens. The aspherical surface is used for three surfaces: the image side surface of the negative meniscus lens of the first group G1, the object side surface of the biconvex lens of the second group G2, and the image side surface of the biconcave lens of the second group G2. It has been.

  As shown in FIG. 3, the zoom lens according to the third exemplary embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small.

  The first group G1 of Example 3 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and the second group G2 is disposed after the stop. It consists of a biconvex lens and a biconcave lens. The aspheric surfaces are used for all four surfaces of the first group G1, seven surfaces of the biconvex lens of the second group G2, and seven surfaces of the image side of the biconcave lens of the second group G2.

  As shown in FIG. 4, the zoom lens according to the fourth exemplary embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small. However, in this embodiment, when the distance between the negative meniscus lens and the positive meniscus lens constituting the first group G1 is changed from the wide angle end to the telephoto end, it is once reduced and expanded again. Therefore, it can be said that this negative meniscus lens is the first group, the positive meniscus lens is the second group, and the second group G2 is a negative, positive, and positive three-group zoom lens that constitutes the third group.

  The first group G1 of Example 4 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and the second group G2 is disposed after the stop. And a negative meniscus lens having a convex surface facing the object side. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 5, the zoom lens according to the fifth exemplary embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small.

  The first group G1 of Example 5 includes a biconcave lens and a positive meniscus lens having a convex surface facing the object side, and the second group G2 includes a diaphragm, a biconvex lens disposed thereafter, and a convex surface facing the object side. And a negative meniscus lens. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 6, the zoom lens according to the sixth exemplary embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small.

  The first group G1 of Example 6 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and the second group G2 is disposed after the stop. It consists of a biconvex lens and a negative meniscus lens having a convex surface facing the object side. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 7, the zoom lens according to the seventh exemplary embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. When the first group G1 moves along a concave locus toward the object side, the telephoto end moves to a position closer to the image plane side than the wide-angle end, and the second group G2 moves toward the object side. The interval between G1 and the second group G2 is reduced.

  The first group G1 of Example 7 includes a biconcave lens and a positive meniscus lens having a convex surface facing the object side. The second group G2 includes a diaphragm, a biconvex lens disposed thereafter, and a convex surface facing the object side. And a negative meniscus lens. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 8, the zoom lens according to the eighth embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. When the first group G1 moves along a concave locus toward the object side, the telephoto end moves to a position closer to the image plane side than the wide-angle end, and the second group G2 moves toward the object side. The interval between G1 and the second group G2 is reduced.

  The first group G1 of Example 8 includes a biconcave lens and a positive meniscus lens having a convex surface directed toward the object side. The second group G2 includes a diaphragm, a biconvex lens disposed thereafter, and a convex surface toward the object side. And a negative meniscus lens. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 9, the zoom lens according to the ninth embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small.

  The first group G1 of Example 9 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and the second group G2 is disposed after the stop. It consists of a biconvex lens and a negative meniscus lens having a convex surface facing the object side. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 10, the zoom lens according to the tenth embodiment includes a first group G1 having a negative refractive power and a second group G2 having a positive refractive power, and zooms from a wide angle end to a telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small.

  The first group G1 of Example 10 includes a biconcave lens and a positive meniscus lens having a convex surface facing the object side, and the second group G2 includes a diaphragm, a biconvex lens disposed thereafter, and a biconcave lens. Become. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 11, the zoom lens of Example 11 includes a first group G1 having negative refractive power and a second group G2 having positive refractive power, and zooms from the wide-angle end to the telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small.

  The first group G1 of Example 11 includes a biconcave lens and a positive meniscus lens having a convex surface facing the object side, and the second group G2 includes an aperture, a biconvex lens disposed thereafter, and a biconcave lens. Become. An aspheric surface is used for all eight lens surfaces.

  As shown in FIG. 12, the zoom lens according to the twelfth embodiment includes a first group G1 having negative refractive power and a second group G2 having positive refractive power, and zooms from the wide angle end to the telephoto end when focusing on an object point at infinity. In doing so, the first group G1 moves to the image plane side, the second group G2 moves to the object side, and the distance between the first group G1 and the second group G2 becomes small.

  The first group G1 of Example 12 includes a biconcave lens and a positive meniscus lens having a convex surface directed toward the object side. The second group G2 includes a fixed stop S1 having a fixed numerical aperture, and both lenses disposed thereafter. It consists of a convex lens, a biconcave lens, and a shutter S2 arranged thereafter or a filter S2 for adjusting the amount of light (a shutter in the numerical data described later). An aspheric surface is used for all eight lens surfaces.

  In this embodiment, the value of α / β in the conditional expression (24) is α / β = 0.395, and the value of φβ / φα in the conditional expression (25) is φβ / φα = 0.727. It is.

Hereinafter, numerical data of each embodiment described above, but the symbols are outside the above, f is the focal length, F _NO is the F-number, 2 [omega is field angle, WE denotes a wide angle end, ST intermediate state, TE is The telephoto end, r ₁ , r ₂ ... Is the radius of curvature of each lens surface, d ₁ , d ₂ ... _Are the distances between the lens surfaces, n _d1 , n _d2 are the refractive index of the d-line of each lens, ν _d1 , ν _d2 ... is the Abbe number of each lens. The aspherical shape is represented by the following expression, where x is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰
Here, r is a paraxial radius of curvature, K is a conical coefficient, and A ₄ , A ₆ , A ₈ , and A ₁₀ are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively.

Example 1
r ₁ = 26.2927 d ₁ = 0.8000 n _d1 = 1.80610 ν _d1 = 40.92
r ₂ = 9.0883 (aspherical surface) d ₂ = 0.6148
r ₃ = 14.1944 d ₃ = 0.8334 n _d2 = 1.77250 ν _d2 = 49.60
r ₄ = 6.9111 d ₄ = 2.8837
_{r 5 = 10.5856 d 5 = 1.7959} n d3 = 1.84666 ν d3 = 23.78
r ₆ = 20.0441 d ₆ = (variable)
r ₇ = ∞ (aperture) d ₇ = 0.8000
r ₈ = 5.4545 (aspherical surface) d ₈ = 3.7931 n _d4 = 1.72916 ν _d4 = 54.68
r ₉ = -20.9087 d ₉ = 0.0998
r ₁₀ = 47.4258 d ₁₀ = 0.8000 n _d5 = 1.84666 ν _d5 = 23.78
r ₁₁ = 6.1276 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 18.7959 d ₁₂ = 1.4434 n _d6 = 1.72916 ν _d6 = 54.68
r ₁₃ = 551.0655 d ₁₃ = (variable)
r ₁₄ = ∞ d ₁₄ = 1.4400 n _d7 = 1.54771 ν _d7 = 62.84
r ₁₅ = ∞ d ₁₅ = 0.8000
_{r 16 = ∞ d 16 = 0.8000} n d8 = 1.51633 ν d8 = 64.14
r ₁₇ = ∞ d ₁₇ = 1.0000
r ₁₈ = ∞ (image plane)
Aspherical coefficient second surface K = 0
A ₄ = -2.0473 × 10 ^-4
A ₆ = -6.7749 × 10 ^-8
A ₈ = -7.7201 × 10 ^-8
A ₁₀ = 3.8688 × 10 ^-10
8th surface K = 0
A ₄ = -1.6034 × 10 ^-4
A ₆ = -1.7070 × 10 ^-5
A ₈ = 8.1032 × 10 ^-7
A ₁₀ = -7.1759 × 10 ^-8
11th surface K = 0
A ₄ = 1.9918 × 10 ^-3
A ₆ = 6.2296 × 10 ^-5
A ₈ = 1.1863 × 10 ^-5
A ₁₀ = -1.3691 × 10 ^-7
Zoom data (∞)
WE ST TE
f (mm) 5.20857 9.31762 16.19691
F _NO 2.5577 3.3111 4.5000
2ω (°) 65.03 39.22 23.17
d ₆ 18.99871 7.84626 1.45849
d ₁₁ 3.77564 8.60826 15.35061
d ₁₃ 2.44254 1.88102 1.85510
.

(Example 2)
r ₁ = 1148.3249 d ₁ = 1.2000 n _d1 = 1.80610 ν _d1 = 40.92
r ₂ = 6.1717 (aspheric surface) d ₂ = 3.7760
r ₃ = 15.4134 d ₃ = 1.5933 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 70.9107 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.8000
r ₆ = 6.0352 (aspherical surface) d ₆ = 5.2334 n _d3 = 1.72916 ν _d3 = 54.68
r ₇ = -13.5021 d ₇ = 0.1639
r ₈ = -69.4120 d ₈ = 0.8000 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 6.8167 (aspherical surface) d ₉ = (variable)
r ₁₀ = 34.9998 d ₁₀ = 1.5217 n _d5 = 1.72916 ν _d5 = 54.68
r ₁₁ = -32.6791 d ₁₁ = (variable)
r ₁₂ = ∞ d ₁₂ = 1.4400 n _d6 = 1.54771 ν _d6 = 62.84
r ₁₃ = ∞ d ₁₃ = 0.8000
r ₁₄ = ∞ d ₁₄ = 0.8000 n _d7 = 1.51633 ν _d7 = 64.14
r ₁₅ = ∞ d ₁₅ = 1.0000
r ₁₆ = ∞ (image plane)
Aspherical coefficient second surface K = 0
A ₄ = -5.1669 × 10 ^-4
A ₆ = -7.7150 × 10 ^-6
A ₈ = 1.6525 × 10 ^-7
A ₁₀ = -1.2782 × 10 ^-8
6th surface K = 0
A ₄ = -2.1967 × 10 ^-4
A ₆ = -1.5855 × 10 ^-5
A ₈ = 7.1172 × 10 ^-7
A ₁₀ = -4.6968 × 10 ^-8
9th surface K = 0
A ₄ = 1.7941 × 10 ^-3
A ₆ = 3.4075 × 10 ^-5
A ₈ = 1.1892 × 10 ^-5
A ₁₀ = -6.1232 × 10 ^-7
Zoom data (∞)
WE ST TE
f (mm) 5.23086 9.31792 16.19444
F _NO 2.4099 3.2607 4.5000
2ω (°) 64.81 39.22 23.17
d ₄ 18.04672 7.98753 1.45849
d ₉ 2.79240 9.20000 16.71529
d ₁₁ 3.16900 1.86959 1.81786
.

(Example 3)
r ₁ = 76.7196 (aspherical surface) d ₁ = 1.2000 n _d1 = 1.78800 ν _d1 = 47.37
r ₂ = 6.6378 (aspherical surface) d ₂ = 3.0972
r ₃ = 10.9897 (aspherical surface) d ₃ = 1.2062 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 18.4564 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.8000
r ₆ = 5.1898 (aspherical surface) d ₆ = 3.8593 n _d3 = 1.69350 ν _d3 = 53.21
r ₇ = -9.7019 (aspherical surface) d ₇ = 0.0000
r ₈ = -1.047 × 10 ⁵ d ₈ = 0.8000 n _d4 = 1.80518 ν _d4 = 25.42
r ₉ = 5.8643 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.4400 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.8000
r ₁₂ = ∞ d ₁₂ = 0.8000 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.0000
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0
A ₄ = 4.6231 × 10 ^-4
A ₆ = -9.3090 × 10 ^-6
A ₈ = 5.9496 × 10 ^-8
A ₁₀ = 0
Second side K = 0
A ₄ = 2.2771 × 10 ^-4
A ₆ = -2.1739 × 10 ^-6
A ₈ = -3.9590 × 10 ^-7
A ₁₀ = 0
Third side K = 0
A ₄ = -7.1846 × 10 ^-4
A ₆ = -1.2111 × 10 ^-5
A ₈ = -2.4843 × 10 ^-7
A ₁₀ = 0
4th surface K = 0
A ₄ = -7.1646 × 10 ^-4
A ₆ = -1.4283 × 10 ^-5
A ₈ = -4.2107 × 10 ^-8
A ₁₀ = 0
6th surface K = 0
A ₄ = -6.7488 × 10 ^-4
A ₆ = -1.4547 × 10 ^-5
A ₈ = -8.4502 × 10 ^-6
A ₁₀ = 0
Surface 7 K = 0
A ₄ = -1.2345 × 10 ^-3
A ₆ = -2.0213 × 10 ^-5
A ₈ = -4.5953 × 10 ^-9
A ₁₀ = 0
9th surface K = 0
A ₄ = 3.6259 × 10 ^-3
A ₆ = 2.3086 × 10 ^-4
A ₈ = 2.6515 × 10 ^-6
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 5.41072 7.95613 16.01169
F _NO 2.8455 3.2387 4.5000
2ω (°) 63.07 45.30 23.43
d ₄ 19.41025 10.42151 0.80861
d ₉ 6.59089 8.30259 13.69450
.

Example 4
r ₁ = 31.3163 (aspherical surface) d ₁ = 1.2000 n _d1 = 1.78800 ν _d1 = 47.37
r ₂ = 6.3077 (aspherical surface) d ₂ = (variable)
r ₃ = 15.6288 (aspherical surface) d ₃ = 1.6305 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 29.8364 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.8000
r ₆ = 6.1475 (aspherical surface) d ₆ = 4.3722 n _d3 = 1.69350 ν _d3 = 53.21
r ₇ = -7.5487 (aspherical surface) d ₇ = 0.0000
r ₈ = 1.278 × 10 ⁶ (aspherical surface) d ₈ = 0.8000 n _d4 = 1.78472 ν _d4 = 25.68
r ₉ = 6.1534 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.4400 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.8000
r ₁₂ = ∞ d ₁₂ = 0.8000 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.0000
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0
A ₄ = 2.1781 × 10 ^-4
A ₆ = -2.4700 × 10 ^-6
A ₈ = 6.7661 × 10 ^-9
A ₁₀ = 0
Second side K = 0
A ₄ = 2.9274 × 10 ^-6
A ₆ = 5.4318 × 10 ^-7
A ₈ = -2.7932 × 10 ^-7
A ₁₀ = 0
Third side K = 0
A ₄ = -6.8760 × 10 ^-4
A ₆ = -5.4772 × 10 ^-6
A ₈ = -2.7113 × 10 ^-7
A ₁₀ = 0
4th surface K = 0
A ₄ = -7.6115 × 10 ^-4
A ₆ = -5.5172 × 10 ^-6
A ₈ = -1.2101 × 10 ^-7
A ₁₀ = 0
6th surface K = 0
A ₄ = -7.9971 × 10 ^-4
A ₆ = -3.2700 × 10 ^-5
A ₈ = -5.6059 × 10 ^-6
A ₁₀ = 0
Surface 7 K = 0
A ₄ = -6.4906 × 10 ^-4
A ₆ = -1.1601 × 10 ^-5
A ₈ = -1.3240 × 10 ^-7
A ₁₀ = 0
8th surface K = 0
A ₄ = -1.3589 × 10 ^-5
A ₆ = 5.4041 × 10 ^-8
A ₈ = 2.3274 × 10 ^-6
A ₁₀ = 0
9th surface K = 0
A ₄ = 2.3384 × 10 ^-3
A ₆ = 1.3074 × 10 ^-4
A ₈ = 3.0058 × 10 ^-9
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 5.52504 7.90361 15.98209
F _NO 2.9283 3.2981 4.5000
2ω (°) 62.00 45.57 23.47
d ₂ 3.15754 2.83342 3.17975
d ₄ 19.07192 10.96142 0.39391
d ₉ 6.86971 8.50151 13.80700
.

(Example 5)
r ₁ = -12.193 (aspherical surface) d ₁ = 1.20 n _d1 = 1.78800 ν _d1 = 47.37
r ₂ = 10.585 (aspherical surface) d ₂ = 1.14
r ₃ = 6.202 (aspherical surface) d ₃ = 0.84 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 7.845 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.80
r ₆ = 3.456 (aspherical surface) d ₆ = 3.10 n _d3 = 1.69350 ν _d3 = 53.21
r ₇ = -5.866 (aspherical surface) d ₇ = 0.00
r ₈ = 59.892 (aspherical surface) d ₈ = 0.80 n _d4 = 1.80518 ν _d4 = 25.42
r ₉ = 3.400 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.80
r ₁₂ = ∞ d ₁₂ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.00
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 7.28875 × 10 ^-3
A ₆ = -3.16079 × 10 ^-4
A ₈ = 5.59240 × 10 ^-6
A ₁₀ = 0
Second side K = 0.000
A ₄ = 6.08993 × 10 ^-3
A ₆ = 7.92220 × 10 ^-4
A ₈ = -3.77695 × 10 ^-5
A ₁₀ = 0
Third side K = 0.000
A ₄ = -8.25212 × 10 ^-3
A ₆ = 1.05654 × 10 ^-3
A ₈ = -5.98956 × 10 ^-5
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -8.12513 × 10 ^-3
A ₆ = 7.44821 × 10 ^-4
A ₈ = -4.70205 × 10 ^-5
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -5.56006 × 10 ^-4
A ₆ = 3.61032 × 10 ^-5
A ₈ = -1.57815 × 10 ^-5
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 2.56154 × 10 ^-3
A ₆ = -5.93015 × 10 ^-4
A ₈ = 8.21499 × 10 ^-5
A ₁₀ = 0
8th surface K = 0.000
A ₄ = -1.61498 × 10 ^-2
A ₆ = 2.62229 × 10 ^-4
A ₈ = 1.11700 × 10 ^-4
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = -1.33711 × 10 ^-2
A ₆ = 1.83066 × 10 ^-3
A ₈ = 1.80922 × 10 ^-4
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 5.700 7.600 10.500
F _NO 2.84 3.24 3.86
2ω (°) 60.4 46.4 35.0
d ₄ 5.79 3.28 1.20
d ₉ 3.55 4.78 6.67
.

(Example 6)
r ₁ = 742.482 (aspherical surface) d ₁ = 1.20 n _d1 = 1.88300 ν _d1 = 40.76
r ₂ = 5.785 (aspherical surface) d ₂ = 1.66
r ₃ = 7.599 (aspherical surface) d ₃ = 1.88 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 16.421 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.80
r ₆ = 4.194 (aspherical surface) d ₆ = 3.18 n _d3 = 1.49700 ν _d3 = 81.54
r ₇ = -20.581 (aspherical surface) d ₇ = 0.00
r ₈ = 13.506 (aspherical surface) d ₈ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 6.472 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.80
r ₁₂ = ∞ d ₁₂ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.00
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 9.25825 × 10 ^-4
A ₆ = -2.08555 × 10 ^-5
A ₈ = 1.29524 × 10 ^-7
A ₁₀ = 0
Second side K = 0.000
A ₄ = -1.75234 × 10 ^-4
A ₆ = 6.38980 × 10 ^-5
A ₈ = -2.65816 × 10 ^-6
A ₁₀ = 0
Third side K = 0.000
A ₄ = -1.50510 × 10 ^-3
A ₆ = 3.91584 × 10 ^-5
A ₈ = -3.01945 × 10 ^-7
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -1.01332 × 10 ^-3
A ₆ = 1.61802 × 10 ^-5
A ₈ = 1.03000 × 10 ^-7
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -7.98420 × 10 ^-4
A ₆ = -1.86068 × 10 ^-5
A ₈ = -2.94687 × 10 ^-6
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 2.17134 × 10 ^-3
A ₆ = -3.36530 × 10 ^-4
A ₈ = 2.23456 × 10 ^-5
A ₁₀ = 0
8th surface K = 0.000
A ₄ = 3.99355 × 10 ^-3
A ₆ = -2.87967 × 10 ^-4
A ₈ = 1.70044 × 10 ^-5
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = 5.40085 × 10 ^-3
A ₆ = -1.35135 × 10 ^-5
A ₈ = 3.54182 × 10 ^-5
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 5.472 9.450 16.492
F _NO 2.84 3.49 4.67
2ω (°) 62.2 38.4 22.8
d ₄ 19.39 9.00 2.90
d ₉ 8.11 11.30 16.96
.

(Example 7)
r ₁ = -79.529 (aspherical surface) d ₁ = 1.20 n _d1 = 1.88300 ν _d1 = 40.76
r ₂ = 6.338 (aspherical surface) d ₂ = 2.02
r ₃ = 9.087 (aspherical surface) d ₃ = 2.14 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 25.643 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.80
r ₆ = 4.591 (aspherical surface) d ₆ = 3.76 n _d3 = 1.49700 ν _d3 = 81.54
r ₇ = -19.255 (aspherical surface) d ₇ = 0.00
r ₈ = 13.328 (aspherical surface) d ₈ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 6.340 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.80
r ₁₂ = ∞ d ₁₂ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.00
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 6.90799 × 10 ^-4
A ₆ = -1.17782 × 10 ^-5
A ₈ = 4.88182 × 10 ^-8
A ₁₀ = 0
Second side K = 0.000
A ₄ = -4.06939 × 10 ^-4
A ₆ = 4.52557 × 10 ^-5
A ₈ = -1.51312 × 10 ^-6
A ₁₀ = 0
Third side K = 0.000
A ₄ = -1.03153 × 10 ^-3
A ₆ = 2.22306 × 10 ^-5
A ₈ = -2.57487 × 10 ^-7
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -5.56360 × 10 ^-4
A ₆ = 4.49314 × 10 ^-6
A ₈ = 1.08906 × 10 ^-8
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -5.80555 × 10 ^-4
A ₆ = -3.39765 × 10 ^-6
A ₈ = -2.44132 × 10 ^-6
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 2.25406 × 10 ^-3
A ₆ = -2.80904 × 10 ^-4
A ₈ = 1.27498 × 10 ^-5
A ₁₀ = 0
8th surface K = 0.000
A ₄ = 2.85554 × 10 ^-3
A ₆ = -2.15203 × 10 ^-4
A ₈ = 8.69324 × 10 ^-6
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = 3.48116 × 10 ^-3
A ₆ = 3.63247 × 10 ^-6
A ₈ = 1.69137 × 10 ^-5
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 5.500 11.000 22.000
F _NO 2.84 3.73 5.53
2ω (°) 62.2 33.6 17.2
d ₄ 23.03 8.67 1.49
d ₉ 9.02 13.72 23.11
.

(Example 8)
r ₁ = -60.278 (aspherical surface) d ₁ = 1.20 n _d1 = 1.88300 ν _d1 = 40.76
r ₂ = 7.222 (aspherical surface) d ₂ = 2.07
r ₃ = 8.952 (aspherical surface) d ₃ = 2.08 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 22.635 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.80
r ₆ = 4.814 (aspherical surface) d ₆ = 3.81 n _d3 = 1.49700 ν _d3 = 81.54
r ₇ = -24.368 (aspherical surface) d ₇ = 0.00
r ₈ = 12.210 (aspherical surface) d ₈ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 6.177 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.80
r ₁₂ = ∞ d ₁₂ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.00
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 6.00951 × 10 ^-4
A ₆ = -8.43631 × 10 ^-6
A ₈ = 3.37449 × 10 ^-8
A ₁₀ = 0
Second side K = 0.000
A ₄ = -3.72010 × 10 ^-4
A ₆ = 2.79016 × 10 ^-5
A ₈ = -6.20166 × 10 ^-7
A ₁₀ = 0
Third side K = 0.000
A ₄ = -1.09669 × 10 ^-3
A ₆ = 1.28385 × 10 ^-5
A ₈ = -4.91592 × 10 ^-8
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -6.10641 × 10 ^-4
A ₆ = 3.03012 × 10 ^-6
A ₈ = 3.35101 × 10 ^-8
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -3.63773 × 10 ^-4
A ₆ = -1.22811 × 10 ^-5
A ₈ = -8.74615 × 10 ^-7
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 1.68273 × 10 ^-3
A ₆ = -1.42484 × 10 ^-4
A ₈ = 6.05817 × 10 ^-6
A ₁₀ = 0
8th surface K = 0.000
A ₄ = 1.58428 × 10 ^-3
A ₆ = -8.00129 × 10 ^-6
A ₈ = -1.87986 × 10 ^-6
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = 2.15661 × 10 ^-3
A ₆ = 1.52232 × 10 ^-4
A ₈ = 2.48220 × 10 ^-6
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 5.500 11.870 26.600
F _NO 2.84 3.79 6.02
2ω (°) 62.2 30.6 14.2
d ₄ 29.63 10.40 1.20
d ₉ 9.74 15.00 27.15
.

Example 9
r ₁ = 72.039 (aspherical surface) d ₁ = 1.20 n _d1 = 1.88300 ν _d1 = 40.76
r ₂ = 4.217 (aspherical surface) d ₂ = 1.62
r ₃ = 5.885 (aspherical surface) d ₃ = 1.27 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 9.267 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.80
r ₆ = 3.053 (aspherical surface) d ₆ = 3.93 n _d3 = 1.49700 ν _d3 = 81.54
r ₇ = -6.282 (aspherical surface) d ₇ = 0.00
r ₈ = 6.618 (aspherical surface) d ₈ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 3.348 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.80
r ₁₂ = ∞ d ₁₂ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.00
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 3.17076 × 10 ^-3
A ₆ = -1.37514 × 10 ^-4
A ₈ = 1.96035 × 10 ^-6
A ₁₀ = 0
Second side K = 0.000
A ₄ = 3.08247 × 10 ^-3
A ₆ = 3.63679 × 10 ^-4
A ₈ = -3.34382 × 10 ^-5
A ₁₀ = 0
Third side K = 0.000
A ₄ = -1.89408 × 10 ^-3
A ₆ = 2.05447 × 10 ^-4
A ₈ = -6.40061 × 10 ^-6
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -2.03988 × 10 ^-3
A ₆ = 1.30917 × 10 ^-4
A ₈ = -2.56924 × 10 ^-6
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -1.61253 × 10 ^-3
A ₆ = -7.47302 × 10 ^-5
A ₈ = -2.30842 × 10 ^-5
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 3.13913 × 10 ^-3
A ₆ = -1.53242 × 10 ^-3
A ₈ = 1.98597 × 10 ^-4
A ₁₀ = 0
8th surface K = 0.000
A ₄ = -1.43433 × 10 ^-2
A ₆ = -2.19219 × 10 ^-3
A ₈ = 6.46815 × 10 ^-5
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = -1.54578 × 10 ^-2
A ₆ = -1.19883 × 10 ^-3
A ₈ = 2.38275 × 10 ^-4
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 4.38 6.08 8.45
F _NO 2.84 3.28 3.84
2ω (°) 74.4 57.2 42.8
d ₄ 6.59 3.46 1.42
d ₉ 2.77 4.13 5.86
.

(Example 10)
r ₁ = -31.474 (aspherical surface) d ₁ = 1.20 n _d1 = 1.88300 ν _d1 = 40.76
r ₂ = 6.197 (aspherical surface) d ₂ = 2.48
r ₃ = 10.479 (aspherical surface) d ₃ = 2.20 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 47.491 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.80
r ₆ = 3.789 (aspherical surface) d ₆ = 3.61 n _d3 = 1.49700 ν _d3 = 81.54
r ₇ = -16.623 (aspherical surface) d ₇ = 0.00
r ₈ = -39.726 (aspherical surface) d ₈ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 14.332 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.80
r ₁₂ = ∞ d ₁₂ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.00
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 9.59521 × 10 ^-4
A ₆ = -1.72098 × 10 ^-5
A ₈ = 1.13583 × 10 ^-7
A ₁₀ = 0
Second side K = 0.000
A ₄ = -3.60488 × 10 ^-4
A ₆ = 3.77368 × 10 ^-5
A ₈ = -1.07135 × 10 ^-6
A ₁₀ = 0
Third side K = 0.000
A ₄ = -1.01828 × 10 ^-3
A ₆ = 1.27783 × 10 ^-5
A ₈ = 1.61699 × 10 ^-7
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -5.67770 × 10 ^-4
A ₆ = 1.51253 × 10 ^-6
A ₈ = 1.26398 × 10 ^-7
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -8.01515 × 10 ^-4
A ₆ = -2.76063 × 10 ^-5
A ₈ = -3.86277 × 10 ^-6
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 9.05298 × 10 ^-3
A ₆ = -1.86656 × 10 ^-3
A ₈ = 1.48924 × 10 ^-4
A ₁₀ = 0
8th surface K = 0.000
A ₄ = 9.67002 × 10 ^-3
A ₆ = -1.17161 × 10 ^-3
A ₈ = 7.64468 × 10 ^-5
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = 7.85242 × 10 ^-3
A ₆ = 1.15922 × 10 ^-4
A ₈ = 3.78215 × 10 ^-5
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 4.380 7.516 12.700
F _NO 2.84 3.42 4.40
2ω (°) 74.4 48.0 29.4
d ₄ 19.85 8.42 1.91
d ₉ 6.61 9.22 13.52
.

(Example 11)
r ₁ = -21.847 (aspherical surface) d ₁ = 1.20 n _d1 = 1.88300 ν _d1 = 40.76
r ₂ = 6.937 (aspherical surface) d ₂ = 2.47
r ₃ = 9.213 (aspherical surface) d ₃ = 2.21 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 32.046 (aspherical) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.80
r ₆ = 3.998 (aspherical surface) d ₆ = 3.54 n _d3 = 1.49700 ν _d3 = 81.54
r ₇ = -21.908 (aspherical surface) d ₇ = 0.00
r ₈ = -33.149 (aspherical surface) d ₈ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 17.323 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₁ = ∞ d ₁₁ = 0.80
r ₁₂ = ∞ d ₁₂ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞ d ₁₃ = 1.00
r ₁₄ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 9.33410 × 10 ^-4
A ₆ = -1.30751 × 10 ^-5
A ₈ = 6.70483 × 10 ^-8
A ₁₀ = 0
Second side K = 0.000
A ₄ = -6.18417 × 10 ^-4
A ₆ = 4.10180 × 10 ^-5
A ₈ = -7.84432 × 10 ^-7
A ₁₀ = 0
Third side K = 0.000
A ₄ = -1.01784 × 10 ^-3
A ₆ = 4.66075 × 10 ^-6
A ₈ = 1.15224 × 10 ^-7
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -3.78733 × 10 ^-4
A ₆ = -7.08997 × 10 ^-6
A ₈ = 1.63277 × 10 ^-7
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -8.04530 × 10 ^-4
A ₆ = -3.34025 × 10 ^-5
A ₈ = -6.46621 × 10 ^-6
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 2.52254 × 10 ^-3
A ₆ = -4.58004 × 10 ^-4
A ₈ = 3.15723 × 10 ^-5
A ₁₀ = 0
8th surface K = 0.000
A ₄ = 7.40135 × 10 ^-3
A ₆ = -3.03505 × 10 ^-4
A ₈ = 1.41481 × 10 ^-5
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = 8.67706 × 10 ^-3
A ₆ = 1.94947 × 10 ^-4
A ₈ = 2.90374 × 10 ^-5
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 4.380 8.500 16.900
F _NO 2.84 3.57 5.07
2ω (°) 74.4 42.2 22.2
d ₄ 25.20 9.37 1.00
d ₉ 7.72 11.24 18.43
.

(Example 12)
r ₁ = -285.835 (aspherical surface) d ₁ = 1.20 n _d1 = 1.88300 ν _d1 = 40.76
r ₂ = 5.867 (aspherical surface) d ₂ = 1.82
r ₃ = 8.501 (aspherical surface) d ₃ = 1.90 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 22.434 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (fixed aperture) d ₅ = -0.85
r ₆ = 4.202 (aspherical surface) d ₆ = 3.05 n _d3 = 1.49700 ν _d3 = 81.54
r ₇ = -16.394 (aspherical surface) d ₇ = 0.10
r ₈ = -59.287 (aspherical surface) d ₈ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₉ = 17.675 (aspherical surface) d ₉ = 1.20
r ₁₀ = ∞ (shutter) d ₁₀ = (variable)
r ₁₁ = ∞ d ₁₁ = 1.44 n _d5 = 1.54771 ν _d5 = 62.84
r ₁₂ = ∞ d ₁₂ = 0.80
r ₁₃ = ∞ d ₁₃ = 0.80 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₄ = ∞ d ₁₄ = 1.00
r ₁₅ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 7.70010 × 10 ^-4
A ₆ = -1.56894 × 10 ^-5
A ₈ = 9.34888 × 10 ^-8
A ₁₀ = 0
Second side K = 0.000
A ₄ = -1.15782 × 10 ^-4
A ₆ = 5.84590 × 10 ^-5
A ₈ = -2.50813 × 10 ^-6
A ₁₀ = 0
Third side K = 0.000
A ₄ = -9.83337 × 10 ^-4
A ₆ = 4.53271 × 10 ^-5
A ₈ = -5.50922 × 10 ^-7
A ₁₀ = 0
4th surface K = 0.000
A ₄ = -3.78733 × 10 ^-4
A ₆ = -7.08997 × 10 ^-6
A ₈ = 1.63277 × 10 ^-7
A ₁₀ = 0
6th surface K = 0.000
A ₄ = -1.13708 × 10 ^-3
A ₆ = -3.62429 × 10 ^-5
A ₈ = -1.26007 × 10 ^-5
A ₁₀ = 0
Surface 7 K = 0.000
A ₄ = 1.50876 × 10 ^-3
A ₆ = -4.75141 × 10 ^-4
A ₈ = 2.46413 × 10 ^-5
A ₁₀ = 0
8th surface K = 0.000
A ₄ = 7.86320 × 10 ^-3
A ₆ = -4.05987 × 10 ^-4
A ₈ = 2.42457 × 10 ^-5
A ₁₀ = 0
Surface 9 K = 0.000
A ₄ = 9.22752 × 10 ^-3
A ₆ = 9.75655 × 10 ^-5
A ₈ = 3.39493 × 10 ^-5
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 5.484 9.438 16.500
F _NO 2.84 3.53 4.76
2ω (°) 62.4 38.8 22.8
d ₄ 19.39 9.05 2.90
d ₁₀ 6.84 9.90 15.36
.

  Aberration diagrams at the time of focusing on an object point at infinity in Examples 1 to 3, 5, 6, 9, and 12 are shown in FIGS. In these aberration diagrams, (a) shows the wide-angle end, (b) the intermediate state, and (c) spherical aberration SA, astigmatism AS, distortion DT, and lateral chromatic aberration CC at the telephoto end.

Next, the conditional expressions (a) to (l), (n), (1) to (23), (A), and (B) in the above embodiments are shown below (conditional expression (m) is Same as conditional expression (1)).
Conditional Example Example 1 Example 2 Example 3 Example 4
(a) 18.762 24.567 20.150 20.543
(b) 45.072 42.740 35.805 38.958
(c) 30.532 40.320 30.314 33.650
(d) 75.604 83.060 66.119 72.608
(e) 56.340 (*) 50.104 60.451 66.624
(f) 158.574 149.371 194.349 239.601
(g) 41.093 41.955 35.486 36.566
(h) 0.825 0.811 1.019 0.983
(i) 35.487 39.265 33.765 39.996
(j) 54.558 47.469 47.382 51.017
(k) 0.621 0.717 0.743 0.704
(l) -0.586 -0.382 -0.303 -0.102
(n) 54.68 54.68 53.21 53.21
(*) Shows the combined focal length because it is composed of two negative lenses adjacent to each other.

Conditional Example Example 5 Example 6 Example 7 Example 8
(a) 7.421 10.779 13.164 13.446
(b) 20.694 30.818 34.894 34.786
(c) 25.373 25.894 29.667 29.993
(d) 46.067 56.712 64.561 64.779
(e) 45.737 42.940 42.940 46.843
(f) 184.120 98.892 102.145 106.699
(g) 23.422 47.494 51.398 55.301
(h) 1.583 0.753 0.696 0.647
(i) 22.485 27.290 29.872 31.320
(j) 29.277 100.843 98.241 102.145
(k) 1.267 0.355 0.364 0.350
(l) -0.259 -0.661 -0.615 -0.670
(n) 53.21 81.54 81.54 81.54.

Conditional Example Example 9 Example 10 Example 11 Example 12
(a) 10.545 16.110 16.091 11.856
(b) 26.615 38.230 38.276 32.004
(c) 30.773 28.692 28.236 25.673
(d) 57.388 66.922 66.512 57.677
(e) 33.181 37.735 37.735 42.275
(f) 105.398 100.843 94.988 99.003
(g) 31.229 42.940 46.193 46.043
(h) 0.913 0.664 0.617 0.775
(i) 19.862 24.649 26.012 27.337
(j) 58.554 80.675 86.530 104.133
(k) 0.487 0.353 0.329 0.343
(l) -0.346 -0.629 -0.691 -0.592
(n) 81.54 81.54 81.54 81.54.

Conditional Example Example 1 Example 2 Example 3 Example 4
(1) 1.29675 0.82115 1 1
(2) 0.19174 0.15554 0.17170 0.15467
(3) 0.90100 1.18476 0.86112 0.93614
(4) 0.70676 0.93333 0.70170 0.77895
(5) 1.72916 1.72916 1.69350 1.69350
(6) -0.26087 -0.44698 -0.53493 -0.81438
(7) -0.44087 0.19452 0 0
(8) 0.12920 -0.09821 0 0
(9) 1.12340 1.12949 1.12997 1.00096
(10) 0 0--
(11) -1.07063 0.03429--
(12) 0.06396 0.14680--
(13) 0.50299 0.56783 0.30267 0.27301
(14) 0.19810 0.00456 0.07053 0.17643
(15) 0.55365 0.72187 0.57242 0.57149
(16) 1.04334 0.98935 0.82883 0.90181
(17) -0.58847 -0.01314 -0.19617 -0.49095
(18) -1.46166 -0.97864 -1.36946 -0.98374
(19) -0.77192 -0.21272 -0.81544 -0.51530
(20) 32.51 ° 32.40 ° 31.53 ° 31.00 °
(21) 4.50 4.50 4.50 4.50
(22) 3.10967 3.09594 2.95925 2.89267
(23) 1.44 1.44 1.44 1.44
(a is μm) (a = 3.0) (a = 3.0) (a = 3.0) (a = 3.0)
(A)---3.94
(B) -0.0163 -0.031-.

Conditional Example Example 5 Example 6 Example 7 Example 8
(1) 1.120 2.840 2.814 3.048
(2) 0.205 0.201 0.175 0.174
(3) 0.684 0.724 0.829 0.838
(4) 0.587 0.599 0.687 0.694
(5) 1.69350 1.49700 1.49700 1.49700
(6) -0.589 -0.204 -0.238 -0.198
(7) -0.098 -1.524 -1.445 -1.996
(8) 0.057 0.479 0.476 0.506
(9) 0.984 1.543 1.381 1.283
(Ten) *** *** *** ***
(11) *** *** *** *** ***
(12) *** *** *** *** ***
(13) 0.219 0.258 0.342 0.391
(14) -0.467 0.007 -0.069 -0.091
(15) 0.200 0.301 0.368 0.376
(16) 0.482 0.713 0.808 0.805
(17) 0.768 -0.017 0.171 0.256
(18) -1.511 -1.705 -1.497 -1.727
(19) -1.194 -0.789 -0.530 -0.683
(20) 30.2 ° 31.1 ° 31.1 ° 31.1 °
(21) 3.86 4.67 5.53 6.02
(22) 1.842 3.000 4.000 4.836
(23) 1.44 1.44 1.44 1.44
(a is μm) (a = 3.0) (a = 3.0) (a = 3.0) (a = 3.0).

Conditional Example Example 9 Example 10 Example 11 Example 12
(1) 3.047 0.470 0.314 0.541
(2) 0.169 0.181 0.184 0.228
(3) 1.080 1.007 0.991 0.720
(4) 0.712 0.664 0.654 0.594
(5) 1.49700 1.49700 1.49700 1.49700
(6) -0.486 -0.228 -0.182 -0.256
(7) -0.949 0.419 0.661 0.277
(8) 0.506 -0.361 -0.523 -0.298
(9) 1.097 3.783 4.333 4.207
(Ten) *** *** *** ***
(11) *** *** *** *** ***
(12) *** *** *** *** ***
(13) 0.170 0.217 0.264 0.291
(14) 0.061 -0.139 -0.200 -0.019
(15) 0.370 0.565 0.565 0.332
(16) 0.616 0.885 0.886 0.741
(17) -0.109 0.382 0.592 0.046
(18) -1.336 -1.147 -1.403 -1.556
(19) -0.848 -0.253 -0.403 -0.590
(20) 37.2 ° 37.2 ° 37.2 ° 31.2 °
(21) 3.84 4.4 5.86 4.76
(22) 1.929 2.900 3.858 3.000
(23) 1.44 1.44 1.44 1.44
(a is μm) (a = 3.0) (a = 3.0) (a = 3.0) (a = 3.0).

  The above embodiment can be variously modified within the range of the above-described configuration, such as a single low-pass filter.

  In each of the above-described embodiments, the image side of the third group G3 has a low-pass filter F having a near-infrared sharp cut coat on the incident surface side as shown in the figure. This near-infrared sharp cut coat has a transmittance of 80% or more at a wavelength of 600 nm and a transmittance of 10% or less at a wavelength of 700 nm. Specifically, it is a multilayer film composed of the following 27 layers, for example. However, the design wavelength is 780 nm.

Substrate material Physical film thickness (nm) λ / 4
───────────────────────────────
First layer Al ₂ O ₃ 58.96 0.50
Second layer TiO ₂ 84.19 1.00
Third layer SiO ₂ 134.14 1.00
Fourth layer TiO ₂ 84.19 1.00
5th layer SiO ₂ 134.14 1.00
Sixth layer TiO ₂ 84.19 1.00
Seventh layer SiO ₂ 134.14 1.00
Eighth layer TiO ₂ 84.19 1.00
Ninth layer SiO ₂ 134.14 1.00
10th layer TiO ₂ 84.19 1.00
11th layer SiO ₂ 134.14 1.00
12th layer TiO ₂ 84.19 1.00
13th layer SiO ₂ 134.14 1.00
14th layer TiO ₂ 84.19 1.00
15th layer SiO ₂ 178.41 1.33
16th layer TiO ₂ 101.03 1.21
17th layer SiO ₂ 167.67 1.25
18th layer TiO ₂ 96.82 1.15
19th layer SiO ₂ 147.55 1.05
20th layer TiO ₂ 84.19 1.00
21st layer SiO ₂ 160.97 1.20
22nd layer TiO ₂ 84.19 1.00
23rd layer SiO ₂ 154.26 1.15
24th layer TiO ₂ 95.13 1.13
25th layer SiO ₂ 160.97 1.20
26th layer TiO ₂ 99.34 1.18
27th layer SiO ₂ 87.19 0.65
───────────────────────────────
Air.

  The transmittance characteristics of the near infrared sharp cut coat are as shown in FIG.

  Further, the color reproducibility of the electronic image is further improved by providing a color filter for reducing the transmission of colors in the short wavelength region as shown in FIG. ing.

  Specifically, with this filter or coating, the ratio of the transmittance of the wavelength of 420 nm to the transmittance of the wavelength having the highest transmittance at a wavelength of 400 nm to 700 nm is 15% or more, and 400 nm to the transmittance of the highest wavelength. It is preferable that the ratio of the transmittances of the wavelengths is 6% or less.

  Thereby, it is possible to reduce the difference between the recognition of the color of the human eye and the color of the image to be captured and reproduced. In other words, it is possible to prevent deterioration of the image due to the human eye easily recognizing a short wavelength color that is difficult to be recognized by human vision.

  If the ratio of the transmittance at the wavelength of 400 nm exceeds 6%, the single wavelength castle which is difficult to be recognized by the human eye is regenerated to a recognizable wavelength. If the ratio is less than 15%, the reproduction of wavelength castles that can be recognized by humans becomes low, and the color balance becomes poor.

  Such means for limiting the wavelength is more effective in an imaging system using a complementary color mosaic filter.

  In each of the above embodiments, as shown in FIG. 21, the coating has a transmittance of 0% at a wavelength of 400 nm, a transmittance of 90% at 420 nm, and a transmittance peak of 100% at 440 nm.

  By multiplying the action with the above-mentioned near infrared sharp cut coat, the transmittance at 400 nm is peaked at 99%, the transmittance at 400 nm is 0%, the transmittance at 420 nm is 80%, and the transmittance at 600 nm is 82%. The transmittance at 700 nm is 2%. As a result, more faithful color reproduction is performed.

  In addition, the low-pass filter F uses three types of filters with crystal axes in the horizontal (= 0 °) and ± 45 ° directions when projected on the image plane in the optical axis direction, respectively. In this case, moire suppression is performed by shifting by SQRT (1/2) × a horizontally in the direction of a μm and ± 45 °. Here, SQRT is a square route and means a square root as described above.

  Further, on the image pickup surface I of the CCD, as shown in FIG. 22, a complementary color mosaic filter in which four color filters of cyan, magenta, yellow, and green are provided in a mosaic pattern corresponding to the image pickup pixels is provided. ing. These four types of color filters are arranged in a mosaic so that each of them has approximately the same number and adjacent pixels do not correspond to the same type of color filter. Thereby, more faithful color reproduction is possible.

  Specifically, the complementary color mosaic filter is composed of at least four types of color filters as shown in FIG. 22, and the characteristics of the four types of color filters are preferably as follows.

The green color filter G has a spectral intensity peak at the wavelength _GP ,
Yellow filter element Y _e has a spectral strength peak at a wavelength Y _P,
Each cyan filter element C has a spectral strength peak at a wavelength C _P,
The magenta color filter M has peaks at wavelengths M _P1 and M _P2 and satisfies the following conditions.

510 nm <G _P <540 nm
5 nm <Y _P −G _P <35 nm
−100 nm <C _P −G _P <−5 nm
430 nm <M _P1 <480 nm
580 nm <M _P2 <640 nm
Further, the green, yellow, and cyan color filters have an intensity of 80% or more at a wavelength of 530 nm with respect to each spectral intensity peak, and the magenta color filter has an intensity of 10% at a wavelength of 530 nm. From the viewpoint of improving the color reproducibility, it is more preferable that the strength is 50% to 50%.

An example of each wavelength characteristic in each of the above embodiments is shown in FIG. The green color filter G has a spectral intensity beak at 525 nm. The yellow color filter Y _e has a spectral intensity peak at 555 nm. The cyan color filter C has a spectral intensity peak at 510 nm. The magenta color filter M has peaks at 445 nm and 620 nm. In each color filter at 530 nm, G is 99%, _Ye is 95%, C is 97%, and M is 38% with respect to the respective spectral intensity peaks.

In the case of such a complementary color filter, the following signal processing is performed electrically with a controller (not shown) (or a controller used in a digital camera),
Luminance signal Y = | G + M + Y _e + C | × 1/4
Color signal R−Y = | (M + Y _e ) − (G + C) |
B−Y = | (M + C) − (G + Y _e ) |
The signal is converted into R (red), G (green), and B (blue) signals.

  By the way, the arrangement position of the above-mentioned near infrared sharp cut coat may be any position on the optical path. Further, the number of low-pass filters F may be two or one as described above.

  FIG. 24 shows details of the aperture stop portion of each embodiment. Brightness can be adjusted in 0, −1, −2, −3, and −4 steps at the stop position on the optical axis between the first group G1 and the second group G2 of the imaging optical system. A turret 10 is arranged. The turret 10 has an opening 1A having a circular shape with a diameter of about 4 mm and a fixed space (the transmittance for a wavelength of 550 nm is 100%), and the opening of the opening 1A for −1 correction. An opening 1B made of a transparent parallel plate having a fixed opening shape having an opening area that is about half the area (the transmittance for the wavelength of 550 nm is 99%), a circular opening having the same area as the opening 1B, and −2 steps In order to correct to -3 and -4 stages, apertures 1C, 1D, and 1E provided with ND filters having transmittances of 50%, 25%, and 13% for a wavelength of 550 nm, respectively, are provided.

  The amount of light is adjusted by arranging one of the openings at the aperture position by turning the turret 10 around the rotation shaft 11.

Further, when the effective F number F _no ′ satisfies F _no ′> a / 0.4 μm, an ND filter having a transmittance of less than 80% for a wavelength of 550 nm is arranged in the opening. Specifically, in the first embodiment, the effective F value at the telephoto end satisfies the above equation when the effective F value, which is -2 steps with respect to the full aperture (0 steps), is 9.0. There is a corresponding opening of 1C. This suppresses image degradation due to the diffraction phenomenon of the stop.

  An example in which the turret 10 'shown in FIG. 25A is used instead of the turret 10 shown in FIG. Adjust the brightness of the 0th, -1st, -2nd, -3rd, and -4th steps to the aperture stop position on the optical axis between the first group G1 and the second group G2 of the imaging optical system. The possible turret 10 'is arranged. The turret 10 'has an opening shape with an opening of 0A that is adjusted to be zero and a circular and fixed opening 1A' that has a diameter of about 4mm, and an opening that has an opening area that is about half of the opening area of the opening 1A 'for correcting -1 step. The opening 1B ′ having a fixed shape and the opening area are further reduced in order, and the openings 1C ′, 1D ′, and 1E ′ having fixed shapes for correction to −2, 3 and 4 steps are provided. is doing. The amount of light is adjusted by arranging one of the openings at the stop position by turning the turret 10 ′ around the rotation shaft 11.

  Further, optical low-pass filters having different spatial frequency characteristics are arranged from 1A ′ to 1D ′ in the plurality of openings. Then, as shown in FIG. 25B, the spatial frequency characteristic of the optical filter is set higher as the aperture diameter becomes smaller, thereby suppressing image deterioration due to diffraction phenomenon due to narrowing down. Each curve in FIG. 25B shows the spatial frequency characteristics of only the low-pass filter, and the characteristics including diffraction of each diaphragm are set to be equal.

Next, as described above, with regard to the shape of the fixed aperture in the case where an aperture stop (fixed aperture) having a fixed shape and a filter or shutter for adjusting the amount of light are arranged in the zoom lens used in the electronic image pickup apparatus of the present invention, as described above. The open F number F at the end is the minimum pixel pitch a (unit: mm) of the electronic image sensor.
When 1.5 × 10 ³ × a / 1 mm <F,
It is desirable to set the length of the aperture stop in the vertical direction or the horizontal direction of the imaging surface to be longer than the length of the aperture stop in the diagonal direction of the imaging surface.

  For example, by using any one of the shapes shown in FIGS. 26A to 26C, the influence of diffraction can be reduced. For example, it is preferable to use a horizontally long shape for the aperture stop, particularly in photographing where it is desired to reduce the influence of diffraction in the horizontal direction.

Also,
When 1.5 × 10 ³ × a / 1 mm> F,
It is desirable to set the length of the aperture stop in the vertical direction or the horizontal direction of the imaging surface to be shorter than the length of the aperture stop in the diagonal direction of the imaging surface.

  For example, by using one of the shapes shown in FIGS. 27A to 27C, the influence of geometric optical aberration can be reduced. For example, it is preferable to use a vertically long shape for the aperture stop, particularly in photographing where it is desired to reduce the influence of the geometric optical aberration in the horizontal direction.

  By the way, in Example 12 described above, the interval between the fixed aperture S1 and the next lens surface is a negative value (−0.85) because the position of the lens surface is relative to the position of the fixed aperture S1. This is because it is located in a direction opposite to the optical axis direction. In this numerical example, the fixed aperture is a flat plate, but it is of course possible to apply black to a lens surface having a circular aperture (see FIG. 31). Further, a funnel-shaped diaphragm as shown in FIG. 28 may be covered along the inclination of the convex lens surface, or the diaphragm may be formed by a lens frame holding the lens.

  In Example 12, the filter S2 is provided in the air space on the image side of the second lens group G2. In adjusting the amount of light, as shown in FIG. 29, the opening 1A ″ of the turret 10 ″ is a transparent surface or a hollow opening, the opening 1B ″ is an ND filter having a transmittance of 1/2, and the opening 1C ″ is a transmittance of 1/4. As the ND filter, the aperture 1D ″ may be a turret-shaped filter provided with an ND filter having a transmittance of 1/8.

  Further, as the filter S2, a filter surface capable of adjusting the amount of light so as to suppress unevenness in the amount of light may be provided. For example, as shown in FIG. 30, the light intensity is centered concentrically as shown in FIG. It is good also as a structure which arrange | positions the filter which falls so much.

  Further, as schematically shown in FIG. 31, the filter S2 may be inserted into and removed from the optical path by swinging. In particular, in the case of the twelfth embodiment, since there is a space after the second lens group G2, this rocking structure that saves space can be used.

  Further, in order to reduce the ghost caused by the reflected light of the ND filter, the filter S2 for adjusting the light amount may be inclined with respect to the optical axis as schematically shown in FIG. At this time, if the filter S2 has a swing structure, the moving angle at the time of swing can be in an acute angle range, so that the photographing operation can be speeded up.

  The filter S2 for adjusting the light amount may be configured to adjust the light amount by changing the polarization direction of the two polarizing filters. Further, a shutter may be provided instead of the filter, or may be provided together. The shutter may be a focal plane shutter with a moving curtain arranged in the vicinity of the image plane, or various shutters such as a two-lens lens shutter, a focal plane shutter, and a liquid crystal shutter provided in the middle of the optical path.

  FIG. 33 shows an example of the shutter. FIG. 33 shows an example of a rotary focal plane shutter which is one of the focal plane shutters. FIG. 33 (a) is a view seen from the back side, and FIG. 33 (b) is a view seen from the front side. is there. A shutter substrate 15 is arranged immediately before the image plane or at an arbitrary optical path position. The substrate 15 is provided with an opening 16 that transmits an effective light beam of the optical system. Reference numeral 17 denotes a rotary shutter curtain. Reference numeral 18 denotes a rotary shaft of the rotary shutter curtain 17. The rotary shaft 18 rotates with respect to the substrate 15 and is integrated with the rotary shutter curtain 17. The rotating shaft 18 is connected to gears 19 and 20 on the surface of the substrate 15. The gears 19 and 20 are connected to a motor (not shown).

  In such a configuration, the rotary shutter curtain 17 is configured to rotate about the rotation shaft 18 via the gears 19 and 20 and the rotation shaft 18 by driving a motor (not shown).

  The rotary shutter curtain 17 is formed in a substantially semicircular shape and shields and retreats the opening 16 of the substrate 15 by rotation, thereby serving as a shutter. The shutter speed is adjusted by changing the rotating speed of the rotary shutter curtain 17.

  FIGS. 34A to 34D are views of the rotary shutter curtain 17 rotating from the image plane side. It moves in the order of (a), (b), (c), (d), and (a) in the figure with time.

  As described above, by arranging an aperture stop with a fixed shape and a filter or shutter for adjusting the amount of light at different positions in the zoom lens, the amount of light can be adjusted with the filter and shutter while maintaining the high image quality while suppressing the influence of diffraction. It is possible to obtain an electronic imaging apparatus that can perform the above-described process and can shorten the overall length of the zoom lens.

  The electronic image pickup apparatus of the present invention as described above is an image pickup apparatus that forms an object image with a zoom lens and receives the image on an image pickup device such as a CCD or a silver salt film to take a picture, particularly a digital camera or video camera, The present invention can be used for personal computers and telephones, which are examples of information processing apparatuses, particularly mobile phones that are convenient to carry. The embodiment is illustrated below.

  FIG. 35 to FIG. 37 are conceptual diagrams of structures in which the zoom lens according to the present invention is incorporated in the photographing optical system 41 of the digital camera. 35 is a front perspective view showing the appearance of the digital camera 40, FIG. 36 is a rear perspective view thereof, and FIG. 37 is a cross-sectional view showing the configuration of the digital camera 40. In this example, the digital camera 40 includes a photographing optical system 41 having a photographing optical path 42, a finder optical system 43 having a finder optical path 44, a shutter 45, a flash 46, a liquid crystal display monitor 47, and the like. When the shutter 45 disposed in the position is pressed, photographing is performed through the photographing optical system 41, for example, the zoom lens of the first embodiment, in conjunction therewith. An object image formed by the photographing optical system 41 is formed on the imaging surface of the CCD 49 via an optical low-pass filter F provided with a near-infrared cut coat. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the processing means 51. Further, the processing means 51 is connected to a recording means 52 so that a photographed electronic image can be recorded. The recording means 52 may be provided separately from the processing means 51, or may be configured to perform recording / writing electronically using a floppy disk, memory card, MO, or the like. Further, it may be configured as a silver salt camera in which a silver salt film is arranged in place of the CCD 49.

  Further, a finder objective optical system 53 is disposed on the finder optical path 44. The object image formed by the finder objective optical system 53 is formed on the field frame 57 of the Porro prism 55 which is an image erecting member. Behind this polyprism 55 is an eyepiece optical system 59 that guides the erect image to the observer eyeball E. Note that cover members 50 are disposed on the incident side of the photographing optical system 41 and the finder objective optical system 53 and on the exit side of the eyepiece optical system 59, respectively.

  The digital camera 40 configured in this manner is a zoom lens with a large back focus, a photographing optical system 41 having a wide angle of view and a high zoom ratio, good aberration, bright, and a filter that can be arranged with a high back focus. Performance and cost reduction can be realized.

  In the example of FIG. 37, a parallel plane plate is disposed as the cover member 50, but a lens having power may be used.

  Next, a personal computer which is an example of an information processing apparatus in which the zoom lens of the present invention is incorporated as an objective optical system is shown in FIGS. 38 is a front perspective view with the cover of the personal computer 300 opened, FIG. 39 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 40 is a side view of the state of FIG. As shown in FIGS. 38 to 40, the personal computer 300 includes a keyboard 301 for a writer to input information from the outside, information processing means and recording means not shown, and a monitor for displaying information to the operator. 302 and a photographing optical system 303 for photographing the operator himself and surrounding images. Here, the monitor 302 may be a transmissive liquid crystal display element that is illuminated from the back by a backlight (not shown), a reflective liquid crystal display element that reflects and displays light from the front, a CRT display, or the like. Further, in the drawing, the photographing optical system 303 is built in the upper right of the monitor 302. However, the imaging optical system 303 is not limited to the place, and may be anywhere around the monitor 302 or the keyboard 301.

  The photographic optical system 303 includes an objective lens 112 including a zoom lens (abbreviated in the drawing) according to the present invention and an image sensor chip 162 that receives an image on a photographic optical path 304. These are built in the personal computer 300.

  Here, an optical low-pass filter F is additionally attached on the image sensor chip 162 to be integrally formed as an image pickup unit 160, and can be fitted and attached to the rear end of the lens frame 113 of the objective lens 112 with one touch. Therefore, the center alignment of the objective lens 112 and the image sensor chip 162 and the adjustment of the surface interval are unnecessary, and the assembly is simple. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113. The zoom lens driving mechanism in the lens frame 113 is not shown.

  The object image received by the image sensor chip 162 is input to the processing means of the personal computer 300 through the terminal 166 and displayed on the monitor 302 as an electronic image. FIG. A rendered image 305 is shown. The image 305 can also be displayed on the personal computer of the communication partner from a remote location via the processing means, the Internet, or the telephone.

  Next, FIG. 41 shows a telephone which is an example of an information processing apparatus in which the zoom lens of the present invention is incorporated as a photographing optical system, particularly a portable telephone which is convenient to carry. 41 (a) is a front view of the mobile phone 400, FIG. 41 (b) is a side view, and FIG. 41 (c) is a sectional view of the photographing optical system 405. As shown in FIGS. 41A to 41C, the mobile phone 400 includes a microphone unit 401 that inputs an operator's voice as information, a speaker unit 402 that outputs a voice of a call partner, and an operator who receives information. An input dial 403 for inputting information, a monitor 404 for displaying information such as a photographed image and a telephone number of the operator and the other party, a photographing optical system 405, an antenna 406 for transmitting and receiving communication radio waves, and an image And processing means (not shown) for processing information, communication information, input signals, and the like. Here, the monitor 404 is a liquid crystal display element. In the drawing, the arrangement positions of the respective components are not particularly limited to these. The photographing optical system 405 includes an objective lens 112 including a zoom lens (abbreviated in the drawing) according to the present invention disposed on a photographing optical path 407, and an image sensor chip 162 that receives an object image. These are built in the mobile phone 400.

  Here, an optical low-pass filter F is additionally attached on the image sensor chip 162 to be integrally formed as an image pickup unit 160, and can be fitted and attached to the rear end of the lens frame 113 of the objective lens 112 with one touch. Therefore, the center alignment of the objective lens 112 and the image sensor chip 162 and the adjustment of the surface interval are unnecessary, and the assembly is simple. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113. The zoom lens driving mechanism in the lens frame 113 is not shown.

  The object image received by the imaging element chip 162 is input to the processing means (not shown) via the terminal 166 and displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. . Further, when transmitting an image to a communication partner, the processing means includes a signal processing function for converting information of an object image received by the image sensor chip 162 into a signal that can be transmitted.

  The electronic imaging apparatus of the present invention described above can be configured as follows, for example.

    [1] In order from the object side, the lens includes a first lens group including two lenses and having a negative power as a whole, and a second lens group including two lenses and having a positive power as a whole. The zoom that satisfies one or more of the following conditions (a) to (n) can be achieved by changing the air distance between the first lens group and the second lens group to change the focal length of the entire group. An electronic imaging apparatus comprising: a lens; and an electronic imaging element disposed on an image plane side of the zoom lens.

(A) 7 <d _NP · A <27
(B) 20 <t ₁ · A <50
(C) 20 <D ₂ · A <45
(D) 30 <(t ₁ + D ₂ ) · A <90
(E) 30 <−f ₁₁ · A <70
_{(F) 90 <f 12 ·} A <250
(G) 20 <f ₂₁ · A <42
(H) 0.6 <Φ ₂₁ / Φ _w <1.05
(I) 19.5 <R ₂₁ · A <45
(J) 40 <−f ₂₂ · A <140
(K) 0.33 <−Φ ₂₂ / Φ _w <0.80
_{(L) -1 <(R 21} + R 22) / (R 21 -R 22) <0
(M) 0.25 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.4
(N) 72 <ν _d21 <100
However, A = 43.2 / L (L is the diagonal length of the effective imaging region of the electronic imaging device), t ₁ and D ₂ are the total thicknesses on the optical axis of the first lens group and the second lens group, respectively, d _NP is the distance on the optical axis of the two lenses of the first lens group, and f ₁₁ , f ₁₂ , f ₂₁ , and f ₂₂ are the object side lens and image in the two lenses of the first lens group, respectively. Side lens, object side lens in the two lenses of the second lens group, focal length of the image side lens, Φ ₂₁ , Φ ₂₂ , Φ _w are respectively in the two lenses of the second lens group Refracting power of the entire lens at the object side lens, the image side lens, and the wide angle end, R ₂₁ , R ₂₂ , R ₂₃ , and R ₂₄ are curvatures of refractive surfaces in order from the object side constituting the second lens group. The radius, ν _d21, is the Abbe number of the medium of the object side positive lens of the second lens group.

    [2] In order from the object side, the lens consists of two lenses, a negative lens and a positive lens. The first lens group has a negative power as a whole, and from the object side, consists of an aperture stop, a positive lens, and a negative lens The zoom lens is composed of a second lens group having a positive power as a whole. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group becomes small, and the first lens group A zoom lens having a spherical surface, the second lens group having an aspherical surface on the most object side surface, and satisfying the following conditional expressions (1) and (2), and an image plane side of the zoom lens: An electronic imaging device comprising: an electronic imaging device disposed on the substrate.

(1) 0.6 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.0
(2) 0.08 <t _2N / D ₂ <0.28
Where R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, R ₂₄ is a radius of curvature near the optical axis of the image side surface of the negative lens of the second lens group, and D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and t _2N is the image side of the positive lens of the second lens group. This is the distance on the optical axis from the surface to the image side surface of the second lens group.

    [3] In order from the object side, the first lens group having the negative lens on the most object side and the positive lens on the most image side and having negative power as a whole, and the aperture stop, the positive lens, and the negative lens from the object side And having a second lens group having a positive power as a whole and a third lens group consisting of one positive lens, the first lens group and the second lens group when zooming from the wide-angle end to the telephoto end. The distance between the lens groups is reduced, the distance between the second lens group and the third lens group is increased, the first lens group has an aspherical surface, and the second lens group is the most object-side surface. A zoom lens that has an aspherical surface and the shape of the negative lens of the second lens group satisfies the following conditional expression (1), and an electronic imaging device disposed on the image plane side of the zoom lens An electronic imaging device characterized by the above.

(1) 0.6 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.0
However, R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, and R ₂₄ is a radius of curvature near the optical axis of the image side surface of the negative lens of the second lens group. .

    [4] In order from the object side, a first lens group having a negative lens on the most object side and a positive lens on the most image side and having negative power as a whole, and an aperture stop, a positive lens, and a negative lens from the object side And having a second lens group having a positive power as a whole and a third lens group consisting of one positive lens, the first lens group and the second lens group when zooming from the wide-angle end to the telephoto end. The distance between the lens groups is reduced, the distance between the second lens group and the third lens group is increased, the first lens group has an aspherical surface, and the second lens group is the most object-side surface. An electronic imaging apparatus comprising: a zoom lens having an aspherical surface that satisfies the following conditional expression (2); and an electronic imaging device disposed on the image plane side of the zoom lens.

(2) 0.08 <t _2N / D ₂ <0.28
Where D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and t _2N is the thickness of the positive lens of the second lens group. This is the distance on the optical axis from the image side surface to the image side surface of the second lens group.

    [5] In order from the object side, a negative lens and two positive lenses, or a negative lens, a negative lens, and a positive lens, consisting of a first lens group having negative power as a whole, and from the object side, And a second lens group having a positive power as a whole, and when zooming from the wide-angle end to the telephoto end, the first lens group and the second lens group The zoom lens has a small interval, the first lens group has an aspheric surface, the second lens group has an aspheric surface on the most object side, and satisfies the following conditional expressions (1) and (2): And an electronic image pickup device disposed on the image plane side of the zoom lens.

(1) 0.6 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <3.0
(2) 0.08 <t _2N / D ₂ <0.28
Where R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, R ₂₄ is a radius of curvature near the optical axis of the image side surface of the negative lens of the second lens group, and D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and t _2N is the image side of the positive lens of the second lens group. This is the distance on the optical axis from the surface to the image side surface of the second lens group.

    [6] The first lens group includes at least one surface in which the outermost peripheral portion of the refractive surface effective portion has a concave shape on the opposite side to the direction in which the center of curvature exists in the vicinity of the optical axis. 6. The electronic imaging device according to any one of 1 to 5 above.

    [7] The first lens group includes at least two surfaces in which the outermost peripheral portion of the effective refractive surface portion has a concave shape on the opposite side to the direction in which the center of curvature exists in the vicinity of the optical axis. The electronic imaging device according to any one of 1 to 5.

    [8] The electronic imaging apparatus as described in any one of [1] to [5], wherein the most image side surface of the second lens group is an aspherical surface.

    [9] The electronic imaging apparatus according to any one of the above items 2, 3, and 5, wherein the following condition (1) ′ is satisfied instead of the condition (1).

(1) ′ 0.8 <(R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) <2.5
[10] The electronic imaging apparatus according to any one of the above items 2, 3, and 5, wherein the following condition (1) ”is satisfied instead of the condition (1).

(1) "0.9 <(R ₂₃ + R ₂₄ ) / (R ₂₃ -R ₂₄ ) <2.0
[11] The electronic imaging apparatus according to any one of 2, 4, and 5, wherein the following condition (2) ′ is satisfied instead of the condition (2):

(2) '0.1 <t _2N / D ₂ <0.25
[12] The electronic imaging apparatus according to any one of the above items 2, 4, and 5, wherein the following condition (2) ”is satisfied instead of the condition (2).

(2) ”0.12 <t _2N / D ₂ <0.22
[13] The electronic imaging apparatus according to any one of the above items 2, 4, and 5, wherein the following condition (3) is satisfied instead of the condition (2).

(3) 0.3 <D ₂ / f _W <1.5
Where D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and f _W is the total system at the wide angle end. The focal length (when focusing on an object point at infinity).

    [14] The electronic imaging apparatus according to any one of the above items 2, 4, and 5, wherein the following condition (3) ′ is satisfied instead of the condition (2).

(3) ′ 0.5 <D ₂ / f _W <1.4
Where D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and f _W is the total system at the wide angle end. The focal length (when focusing on an object point at infinity).

    [15] The electronic imaging apparatus according to any one of the above items 2, 4, and 5, wherein the following condition (4) is satisfied instead of the condition (2).

(4) 0.24 <D ₂ /L<1.2
Where D ₂ is the thickness on the optical axis from the object-side surface of the positive lens of the second lens group to the image-side surface of the negative lens of the second lens group, and L is the effective imaging region pair of the electronic image sensor. It is angular.

    [16] The electronic imaging apparatus according to any one of the above items 2, 4, and 5, wherein the following condition (4) ′ is satisfied instead of the condition (2).

(4) ′ 0.4 <D ₂ /L<1.12
Where D ₂ is the thickness on the optical axis from the object-side surface of the positive lens of the second lens group to the image-side surface of the negative lens of the second lens group, and L is the effective imaging region pair of the electronic image sensor. It is angular.

    [17] The electronic imaging apparatus as described in any one of [2], [4] and [5] above, wherein the following conditions (3) and (4) are satisfied instead of the condition (2).

(3) 0.3 <D ₂ / f _W <1.5
(4) 0.24 <D ₂ /L<1.2
Where D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and f _W is the total system at the wide angle end. Focal length (when focusing on an object point at infinity), L is the diagonal length of the effective imaging area of the electronic imaging device.

    [18] The electronic imaging device as described in any one of 2 to 17 above, wherein the following condition (5) is satisfied.

(5) 1.6 <n ₂₁ <1.9
Here, n ₂₁ is the refractive index of the positive lens in the second lens group.

    [19] The electronic imaging apparatus as described in any one of 2 to 18 above, wherein the following condition (6) is satisfied.

(6) −1.5 <R ₂₁ / R ₂₂ <0.2
R ₂₁ is a radius of curvature on the optical axis of the object side surface of the positive lens in the second lens group, and R ₂₂ is a radius of curvature on the optical axis of the image side surface of the positive lens in the second lens group.

    [20] The electronic imaging apparatus as described in any one of 2 to 19 above, wherein the following condition (7) is satisfied.

(7) -1.0 <R ₂₂ / R ₂₃ <0.5
Here, R ₂₂ is a radius of curvature on the optical axis of the image side surface of the positive lens in the second lens group, and R ₂₃ is a radius of curvature on the optical axis of the object side surface of the negative lens in the second lens group.

    [21] The electronic imaging apparatus as described in any one of 2 to 20 above, wherein the following condition (8) is satisfied.

(8) -0.3 <R ₂₄ / R ₂₃ <0.5
Here, R ₂₄ is a radius of curvature on the optical axis of the image side surface of the negative lens in the second lens group, and R ₂₃ is a radius of curvature on the optical axis of the object side surface of the negative lens in the second lens group.

    [22] The electronic imaging apparatus as described in any one of 2 to 20 above, wherein the following condition (9) is satisfied.

(9) 0.5 <R ₂₄ / R ₂₁ <2.0
Here, R ₂₄ is a radius of curvature on the optical axis of the image side surface of the negative lens in the second lens group, and R ₂₁ is a radius of curvature on the optical axis of the object side surface of the positive lens in the second lens group.

    [23] The third lens group is a group that moves during focusing, and all the refractive surfaces of the third lens group are refractive surfaces with a small deviation amount that satisfy the following condition (1). 5. The electronic imaging apparatus according to 3 or 4 above.

(10) | abs (Z) | / L <1.5 × 10 ⁻²
Where L is the diagonal length of the effective imaging region of the electronic imaging device, and abs (Z) is the radius of curvature on the optical axis of each refractive surface of the third lens group at a position where the height from the optical axis is 0.35L. This is the amount of deviation in the optical axis direction from the spherical surface to the refractive surface.

    [24] The electronic imaging apparatus as described in 3 or 4 above, wherein the third lens group is a group that moves during focusing, and all the refractive surfaces of the third lens group are spherical surfaces.

    [25] Any of 3, 4, 23, or 24 above, wherein the third lens group is a group that moves during focusing, and the positive lens of the third lens group satisfies the following condition (11): The electronic imaging device of Claim 1.

(11) −2.0 <(R ₃₁ + R ₃₂ ) / (R ₃₁ −R ₃₂ ) <1.0
Here, R ₃₁ is a radius of curvature on the optical axis of the object side surface of the positive lens in the third lens group, and R ₃₂ is a radius of curvature on the optical axis of the image side surface of the positive lens in the third lens group.

[26] In the above-mentioned 3, 4, 23, 24, or 25, the moving amount x ₃ of the third lens group satisfies the following condition (12) when zooming from the wide-angle end to the telephoto end: The electronic imaging device of any one of Claims 1.

(12) −0.5 <x ₃ / √ (f _W · f _T ) <0.5
Where f _W is the focal length of the entire system at the wide-angle end (when focusing on an object point at infinity), and f _T is the focal length of the entire system at the telephoto end (when focusing on an object point at infinity).

[27] When zooming from the wide-angle end to the telephoto end, the movement amount x ₃ of the third lens group is as follows with respect to the change amount x _2-3 of the air gap between the second lens group and the third lens group. 26. The electronic imaging apparatus as set forth in any one of 3, 4, 23, 24, or 25, wherein the condition (B) is satisfied.

(B) 0.005 <| x ₃ / (γ × x _2-3 ) | <0.05
Where γ is the zoom ratio from the wide-angle end to the telephoto end.

    [28] The electronic imaging apparatus as described in any one of [1] to [27], wherein the following condition (13) is satisfied.

(13) Δ (1 / EXP) · √ (f _W · f _T ) <1
Where f _W is the focal length of the entire system at the wide-angle end (when focusing on an object point at infinity), f _T is the focal length of the entire system at the telephoto end (when focusing on an object point at infinity), and Δ (1 / EXP) is the amount of change of the reciprocal of the exit pupil position, and is expressed by the following equation.

Δ (1 / EXP) = | (1 / EXPT) − (1 / EXPW) |
However, EXPT is the exit pupil position at the telephoto end, and EXPW is the exit pupil position at the wide angle end.

    [29] The electronic image pickup apparatus as described in any one of [1] to [28], wherein a zoom ratio of the zoom lens is 2.4 or more.

    [30] The electronic image pickup apparatus as described in any one of [1] to [28], wherein a zoom ratio of the zoom lens is 2.8 or more.

    [31] The electronic imaging apparatus as described in any one of [1] to [30], wherein the most object side surface and the most image side surface of the first lens group are aspherical surfaces.

    [32] The electronic imaging apparatus as described in any one of [1] to [30], wherein the most object side surface and the most image side surface of the second lens group are aspherical surfaces.

    [33] The electronic imaging apparatus as described in any one of [1] to [30], wherein both surfaces of the positive lens in the first lens group are aspherical surfaces.

    [34] The electron as described in any one of 1 to 30 above, wherein all the negative lenses included in the first lens group and the second lens group are meniscus lenses having a convex surface directed toward the object side. Imaging device.

    [35] The electronic imaging apparatus according to any one of [1] to [30], wherein the object side surface of the positive lens of the second lens group is a surface having a refractive power stronger than that of the image side surface.

    [36] The electronic imaging apparatus as described in any one of [1] to [30], wherein the negative lens of the first lens group satisfies the following condition (14).

(14) −0.3 <f _W / R ₁₁ <0.4
Where R ₁₁ is the radius of curvature near the optical axis (on the optical axis) of the first lens surface from the object side of the first lens group, and f _W is the focal length of the entire system at the wide angle end (when focusing on an object point at infinity) ).

    [37] The electron according to any one of [2] to [30], wherein an air interval on an optical axis in contact with the object side of the positive lens of the first lens group satisfies the following condition (15): Imaging device.

(15) 0.3 <d _NP / f _W <1
Where d _NP is the air spacing on the optical axis in contact with the object side of the positive lens in the first lens group, and f _W is the focal length of the entire system at the wide angle end (when focusing on an object point at infinity).

[38] The air gap on the optical axis in contact with the object side of the positive lens in the first lens group satisfies the following condition (15) ^* : Electronic imaging device.

(15) ^* 1 <| d _NP / f ₁ | <3
Where d _NP is the air space on the optical axis in contact with the object side of the positive lens of the first lens group, and f ₁ is the focal length of the first lens group.

    [39] The electronic imaging apparatus as described in any one of [1] to [30], wherein the first lens group satisfies the following condition (16).

(16) 0.4 <t ₁ /L<2.2
Here, t ₁ is the thickness on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the first lens group, and L is the diagonal length of the effective imaging region of the electronic imaging device.

    [40] A first lens group having a negative power and a second lens group having a positive power in order from the object side, the first lens group having a surface on the optical axis on the object side. It has a negative meniscus lens and a positive meniscus lens with a convex surface, and the object side surface of the positive meniscus lens is on the opposite side to the direction in which the center of curvature in the vicinity of the optical axis is present at the outermost peripheral portion of the refractive surface effective portion. An electronic imaging apparatus comprising: a zoom lens that is an aspherical surface having a concave shape; and an electronic imaging device disposed on an image plane side of the zoom lens.

    [41] A negative lens having, in order from the object side, a first lens group having a negative power and a second lens group having a positive power, the first lens group having a concave surface facing the image surface side. And a positive meniscus lens whose surface on the optical axis is convex toward the object side, and the object side surface of the positive meniscus lens is the center of curvature in the vicinity of the optical axis at the outermost peripheral portion of the refractive surface effective portion. A zoom lens that is concave on the side opposite to the direction in which the zoom lens exists and that satisfies the following condition (A), and an electronic image sensor disposed on the image plane side of the zoom lens An electronic imaging device characterized by the above.

(A) −5.0 <(R ₁₃ + R ₁₄ ) / (R ₁₃ −R ₁₄ ) <− 1.7
Where R ₁₃ is the radius of curvature of the object side surface of the positive meniscus lens of the first lens group, and R ₁₄ is the radius of curvature of the image side surface of the positive meniscus lens of the first lens group.

    [42] The electronic imaging apparatus as described in any one of [1] to [40], wherein the following condition (17) is satisfied.

(17) -1 <f ₁ / R ₁₁ <0.5
Here, f ₁ is the focal length of the first lens group, and R ₁₁ is the radius of curvature in the vicinity of the optical axis (on the optical axis) of the most object side surface of the first lens group.

    [43] The positive lens in the first lens group is a positive meniscus lens having a positive radius of curvature in the vicinity of the double-sided optical axis (on the optical axis), and in the effective portion of the refractive surface of each surface. Is an aspheric surface having a concave shape on the opposite side to the direction in which the center of curvature exists near the optical axis, and only one negative lens in the first lens group is used. 43. The electronic imaging apparatus according to any one of the above items 2 to 42, wherein the electronic imaging apparatus is constituted by a single lens.

    [44] The electronic imaging device as described in 43 above, wherein the following conditions (18) and (19) are satisfied.

(18) −2.5 <f ₁ / R ₁₃ <−0.5
(19) -1.5 <f ₁ / R ₁₄ <0.5
Where f ₁ is the focal length of the first lens group, R ₁₃ is the radius of curvature of the object side surface of the positive meniscus lens of the first lens group, and R ₁₄ is the curvature of the image side surface of the positive meniscus lens of the first lens group. Radius.

[45] The electronic imaging apparatus as described in any one of [1] to [44], wherein the half angle of view ω _W at the wide angle end of the zoom lens satisfies the following condition (20).

(20) 28 ° <ω _W <40 °
[46] The electronic imaging apparatus as described in any one of [1] to [45], wherein an open F value F _T at the telephoto end of the zoom lens satisfies the following condition (21).

(21) 2.7 <F _T <5
[47] The electronic imaging apparatus as described in any one of [1] to [46], wherein the zoom ratio γ from the wide-angle end to the telephoto end of the zoom lens satisfies the following condition (22).

(22) 2 <γ <4
[48] A zoom lens having a plurality of lens groups that change the respective focal distances to change the focal length, an aperture stop that is disposed in the optical path and restricts at least the axial beam diameter, and is disposed on the image side thereof. In an electronic imaging apparatus provided with the electronic imaging element,
The aperture stop has a fixed aperture shape, and an electronic image pickup comprising a filter for adjusting the amount of light by changing the transmittance on the optical axis in a space different from the space where the aperture stop is disposed apparatus.

[49] In the above 48, the open F number F at the telephoto end is smaller than the minimum pixel pitch a (unit: mm) of the electronic image sensor.
When 1.5 × 10 ³ × a / 1 mm <F,
The length of the aperture stop in the vertical or horizontal direction of the imaging surface is longer than the length of the aperture stop in the diagonal direction of the imaging surface, or
The open F number F at the telephoto end is smaller than the minimum pixel pitch a (unit: mm) of the electronic image sensor.
When 1.5 × 10 ³ × a / 1 mm> F,
An electronic imaging apparatus, wherein a length of the aperture stop in a vertical direction or a horizontal direction of an imaging surface is shorter than a length of the aperture stop in a diagonal direction of the imaging surface.

    [50] The electronic imaging according to 48, wherein the filter is arranged in a minimum air interval among variable air intervals in the zoom lens or in a longest air interval in a constant air interval. Device.

    [51] The electronic imaging apparatus according to [48], wherein the filter for adjusting the amount of light has at least one transmission surface in which the transmittance of the peripheral portion is higher than the transmittance of the central portion.

    [52] The electronic imaging apparatus according to [48], wherein the filter for adjusting the light amount can be arranged to be inclined with respect to an optical axis.

    [53] In the above 48, the aperture stop is disposed between the lens groups before and after the variable air gap at the time of zooming or at the time of focusing operation, and the filter for adjusting the light amount includes the air gap. Are arranged at different positions.

    [54] In any one of the above 48 to 53, the aperture stop has a position where a perpendicular line extending from the aperture stop to the optical axis intersects with the optical axis is located in the lens medium in the lens group. An electronic imaging device is characterized.

    [55] The electronic imaging apparatus as set forth in 54, wherein the aperture stop is provided in contact with any lens surface in the lens group.

    [56] The electronic imaging apparatus according to any one of 48 to 55, wherein the aperture stop is a caliber plate having an opening on the optical axis side.

    [57] In any one of the above 48 to 56, the zoom lens includes at least a lens unit having a negative refractive power and a lens unit having a positive refractive power arranged immediately after the image side, and has a wide-angle end. The distance between the lens unit having the negative refractive power and the lens unit having the positive refractive power is reduced at the telephoto end, and the aperture stop is moved away from the most image side surface of the lens unit having the negative refractive power. An electronic imaging apparatus, wherein a filter for adjusting the light amount is arranged on an image plane side with respect to the aperture stop.

    [58] The electronic imaging apparatus as set forth in 57, wherein the negative lens group is disposed closest to the object side.

    [59] In the above 57, the zoom lens includes, in order from the object side, the lens group having the negative refractive power and the lens group having the positive refractive power. An electronic imaging apparatus comprising only two lens groups, the lens group having a negative refractive power and the lens group having a positive refractive power.

    [60] The zoom lens according to [57], wherein the zoom lens includes, in order from the object side, only two lens groups, the lens group having the negative refractive power and the lens group having the positive refractive power. An electronic imaging device.

    [61] The electronic imaging apparatus according to any one of 57 to 60, wherein the aperture stop is disposed in an air space immediately before the lens unit having the positive refractive power.

    [62] The electronic imaging apparatus as set forth in any one of [57] to [61], wherein the filter for adjusting the light amount is disposed in an air space immediately after the lens unit having the positive refractive power.

    [63] In any one of 48 to 62 above, the distance on the optical axis between the aperture stop and the entrance surface of the filter for adjusting the amount of light closer to the image side is α, and the filter for adjusting the amount of light An electronic imaging apparatus characterized in that the following condition is always satisfied, where β is the distance on the optical axis from the incident surface to the imaging surface of the electronic imaging element.

(24) 0.01 <α / β <1.0
[64] In any one of 48 to 63 above, when the maximum aperture diameter (diameter) of the aperture stop aperture is φα and the maximum effective diameter (diagonal length) of the filter for adjusting the light amount is φβ. An electronic imaging device characterized by satisfying the following conditions:

(25) 0.5 <φβ / φα <1.5
[65] In any one of 48 to 64 above, the aperture stop is disposed at a variable interval, and both the lens surface immediately before and the lens surface immediately after the aperture stop are directed concave toward the image side, and the aperture stop An electronic imaging apparatus characterized in that the outer shape is a funnel shape that is inclined toward the image side as the distance from the optical axis increases.

    [66] The electronic imaging apparatus according to any one of [48] to [65], wherein the filter for adjusting the light amount is configured to be inserted into and removed from an optical path.

    [67] The electronic imaging apparatus according to [66], wherein the filter for adjusting the amount of light swings in a direction in which a surface approaches parallel to the optical axis when retracting from the optical axis.

[68] A zoom lens having a plurality of lens groups that change the respective focal lengths to change the focal length, an aperture stop that is disposed in the optical path and restricts at least the axial beam diameter, and is disposed on the image side thereof In an electronic imaging apparatus provided with the electronic imaging element,
An electronic imaging apparatus, wherein the aperture stop has a fixed aperture shape, and a shutter is disposed on the optical axis of a space at a position different from the space where the aperture stop is disposed.

    [69] In the above 68, the aperture stop is disposed between the front and rear lens groups sandwiching a variable air interval at the time of zooming or focusing operation, and the shutter is located at a position different from the air interval. An electronic imaging device characterized by being arranged.

    [70] The electronic imaging according to 68 or 69, wherein the aperture stop has a position where a perpendicular line extending from the aperture stop to the optical axis and the optical axis intersect within the lens medium in the lens group. apparatus.

    [71] The electronic imaging apparatus according to [70], wherein the aperture stop is provided in contact with any lens surface in the lens group.

    [72] The electronic imaging apparatus according to any one of 68 to 71, wherein the aperture stop is a caliber plate having an opening on the optical axis side.

    [73] In any one of the above items 68 to 72, the zoom lens includes at least a lens unit having a negative refractive power and a lens unit having a positive refractive power disposed immediately after the image side. The distance between the lens unit having the negative refractive power and the lens unit having the positive refractive power is reduced at the telephoto end, and the aperture stop is moved away from the most image side surface of the lens unit having the negative refractive power. An electronic imaging apparatus, wherein the electronic imaging apparatus is disposed between image side surfaces of a lens unit having a refractive power, and the shutter is disposed closer to the image plane side than the aperture stop.

    [74] The electronic imaging apparatus as set forth in 73, wherein the negative lens group is disposed closest to the object side.

    [75] In 73, the zoom lens includes, in order from the object side, the lens group having the negative refractive power and the lens group having the positive refractive power, and the lens group movable at the time of zooming is An electronic imaging apparatus comprising only two lens groups, the lens group having a negative refractive power and the lens group having a positive refractive power.

    [76] In the above 73, the zoom lens includes only two lens groups, in order from the object side, the lens group having the negative refractive power and the lens group having the positive refractive power. An electronic imaging device.

    [77] The electronic imaging apparatus according to any one of 73 to 76, wherein the aperture stop is disposed in an air space immediately before the lens unit having the positive refractive power.

    [78] The electronic image pickup apparatus according to any one of 73 to 77, wherein the shutter is disposed in an air space immediately after the lens unit having the positive refractive power.

    [79] In any one of 68 to 78, the distance on the optical axis between the aperture stop and the shutter closer to the image side is α ′, and the light to the imaging surface of the shutter and the electronic imaging device An electronic imaging apparatus characterized in that the following condition is always satisfied when the distance on the axis is β ′.

(26) 0.01 <α ′ / β ′ <1.0
[80] In any one of 68 to 79 above, when the maximum aperture diameter (diameter) of the aperture stop aperture is φα and the maximum effective diameter (diagonal length) of the shutter is φβ ′, An electronic imaging apparatus characterized by satisfying a condition.

(27) 0.5 <φβ ′ / φα <1.5
[81] In any one of the above items 68 to 80, the aperture stop is disposed at a variable interval, and the lens surface immediately before and the lens surface immediately after the aperture stop are both directed concave toward the image side, and the aperture stop An electronic imaging apparatus characterized in that the outer shape is a funnel shape that is inclined toward the image side as the distance from the optical axis increases.

  As is apparent from the above description, according to the present invention, it is possible to obtain a zoom lens with a thin collapsible thickness, excellent storage property, high magnification, and excellent imaging performance even in rear focus. It becomes possible to achieve a thin camera.

FIG. 3 is a lens cross-sectional view at a wide angle end when focusing on an object point at infinity of Example 1 of a zoom lens used in the electronic imaging device of the present invention. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of a zoom lens according to Embodiment 2. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of a zoom lens according to Embodiment 3. FIG. 6 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to a fourth exemplary embodiment. FIG. 6 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to a fifth exemplary embodiment. FIG. 6 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to Example 6; FIG. 10 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to a seventh embodiment. FIG. 10 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to an eighth embodiment. FIG. 10 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to Example 9; FIG. 12 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to Example 10; FIG. 12 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to Example 11; FIG. 12 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom lens according to a twelfth embodiment. FIG. 6 is an aberration diagram for Example 1 upon focusing on an object point at infinity. FIG. 6 is an aberration diagram for Example 2 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 3 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 5 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 6 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 9 upon focusing on an object point at infinity. FIG. 14 is an aberration diagram for Example 12 upon focusing on an object point at infinity. It is a figure which shows the transmittance | permeability characteristic of an example of a near-infrared sharp cut coat. It is a figure which shows the transmittance | permeability characteristic of an example of the color filter provided in the emission surface side of a low-pass filter. It is a figure which shows the color filter arrangement | positioning of a complementary color mosaic filter. It is a figure which shows an example of the wavelength characteristic of a complementary color mosaic filter. It is a perspective view which shows the detail of an example of the part of the aperture stop of each Example. It is a figure which shows the detail of another example of the part of the aperture stop of each Example. It is a figure which shows the example of a shape of a fixed aperture when the fixed aperture of the zoom lens by this invention which arrange | positions a fixed aperture and a filter or a shutter is larger than the theoretical limit of F value. It is a figure which shows the example of a shape of a fixed aperture when the fixed aperture of the zoom lens by this invention which arrange | positions a fixed aperture and a filter or a shutter is smaller than the theoretical limit of F value. It is a figure which shows the example of a funnel-shaped fixed aperture_diaphragm | restriction. In Example 12, it is a figure which shows the turret-shaped light quantity adjustment filter which can be utilized. It is a figure which shows the example of the filter which suppresses light quantity nonuniformity. It is a figure which shows the example of the filter inserted / removed by rocking | fluctuation in an optical path. It is a figure which shows the rocking | fluctuation insertion / removal structure of the filter which reduces the ghost by reflected light. It is the back view and front view which show the example of a rotary focal plane shutter. It is a figure which shows a mode that the rotary shutter curtain of the shutter of FIG. 33 rotates. It is a front perspective view which shows the external appearance of the digital camera incorporating the zoom lens by this invention. FIG. 36 is a rear perspective view of the digital camera of FIG. 35. FIG. 36 is a cross-sectional view of the digital camera of FIG. 35. It is the front perspective view which opened the cover of the personal computer in which the zoom lens by this invention was integrated as an objective optical system. It is sectional drawing of the imaging optical system of a personal computer. It is a side view of the state of FIG. 1 is a front view, a side view, and a sectional view of a photographing optical system of a mobile phone in which a zoom lens according to the present invention is incorporated as an objective optical system.

Explanation of symbols

G1 ... 1st group G2 ... 2nd group G3 ... 3rd group F ... Optical low-pass filter C ... Cover glass I ... Image plane E ... Observer eyeball S1 ... Fixed aperture S2 ... Shutter or light quantity adjustment filters 1A, 1B, 1C 1D, 1E ... Opening 1A ', 1B', 1C ', 1D', 1E '... Opening 1A ", 1B", 1C ", 1D" ... Opening 10 ... Turlet 10' ... Turlet 10 "... Turlet 11 ... Rotating shaft DESCRIPTION OF SYMBOLS 15 ... Shutter board | substrate 16 ... Opening part 17 ... Rotary shutter curtain 18 ... Rotating shaft 19, 20 ... Gear 40 ... Digital camera 41 ... Shooting optical system 42 ... Shooting optical path 43 ... Viewfinder optical system 44 ... Viewfinder optical path 45 ... Shutter 46 ... Flash 47 ... LCD monitor 49 ... CCD
DESCRIPTION OF SYMBOLS 50 ... Cover member 51 ... Processing means 52 ... Recording means 53 ... Finder objective optical system 55 ... Porro prism 57 ... Field frame 59 ... Eyepiece optical system 112 ... Objective lens 113 ... Lens frame 114 ... Cover glass 160 ... Imaging unit 162 ... Image sensor chip 166 ... Terminal 300 ... Personal computer 301 ... Keyboard 302 ... Monitor 303 ... Shooting optical system 304 ... Shooting optical path 305 ... Image 400 ... Mobile phone 401 ... Microphone unit 402 ... Speaker unit 403 ... Input dial 404 ... Monitor 405 ... Shooting optics System 406 ... Antenna 407 ... Imaging optical path

Claims (21)

In order from the object side, there are two lenses, a negative lens and a positive lens, or a negative lens, a negative lens, and a positive lens. The first lens group has a negative power as a whole, and an aperture stop from the object side. The first lens group is composed of a two-lens group or a three-lens group including a positive lens and a negative lens, and a second lens group having a positive power as a whole, and when zooming from the wide angle end to the telephoto end Between the first lens group and the second lens group, the first lens group has an aspherical surface, the second lens group has an aspherical surface on the most object side surface, and the following conditional expression (1) '' An electronic imaging apparatus comprising: a zoom lens satisfying '', (4) '''', and an electronic imaging device disposed on an image plane side of the zoom lens.
(1) '''' 0.82115 ≦ (R ₂₃ + R ₂₄ ) / (R ₂₃ −R ₂₄ ) ≦ 1.29675
(4) '''' 0.587 ≦ D ₂ /L<1.12
Where R ₂₃ is a radius of curvature near the optical axis of the object side surface of the negative lens of the second lens group, R ₂₄ is a radius of curvature near the optical axis of the image side of the negative lens of the second lens group, and D ₂ is the thickness on the optical axis from the object side surface of the positive lens of the second lens group to the image side surface of the negative lens of the second lens group, and L is the diagonal length of the effective imaging region of the electronic image sensor. is there.
Electronic imaging apparatus according to claim 1, characterized by satisfying the following condition (5).
(5) 1.6 <n ₂₁ <1.9
Here, n ₂₁ is the refractive index of the positive lens in the second lens group. Electronic imaging apparatus of claim 1, wherein a satisfies the following condition (6).
(6) −1.5 <R ₂₁ / R ₂₂ <0.2
R ₂₁ is a radius of curvature on the optical axis of the object side surface of the positive lens in the second lens group, and R ₂₂ is a radius of curvature on the optical axis of the image side surface of the positive lens in the second lens group. Electronic imaging apparatus according to any one of claims 1 to 3, characterized by satisfying the following condition (7).
(7) -1.0 <R ₂₂ / R ₂₃ <0.5
Here, R ₂₂ is a radius of curvature on the optical axis of the image side surface of the positive lens in the second lens group, and R ₂₃ is a radius of curvature on the optical axis of the object side surface of the negative lens in the second lens group. The following condition (8) the electronic imaging device of any one of claims 1-4, characterized by satisfying the.
(8) -0.3 <R ₂₄ / R ₂₃ <0.5
Here, R ₂₄ is a radius of curvature on the optical axis of the image side surface of the negative lens in the second lens group, and R ₂₃ is a radius of curvature on the optical axis of the object side surface of the negative lens in the second lens group. Electronic imaging apparatus according to any one of claims 1-5, characterized by satisfying the following condition (9).
(9) 0.5 <R ₂₄ / R ₂₁ <2.0
Here, R ₂₄ is a radius of curvature on the optical axis of the image side surface of the negative lens in the second lens group, and R ₂₁ is a radius of curvature on the optical axis of the object side surface of the positive lens in the second lens group. Electronic imaging apparatus according to any one of claims 1-6, characterized by satisfying the following condition (13).
(13) Δ (1 / EXP) · √ (f _W · f _T ) <1
Where f _W is the focal length of the entire system at the wide-angle end (when focusing on an object point at infinity), f _T is the focal length of the entire system at the telephoto end (when focusing on an object point at infinity), and Δ (1 / EXP) is the amount of change of the reciprocal of the exit pupil position, and is expressed by the following equation.
Δ (1 / EXP) = | (1 / EXPT) − (1 / EXPW) |
However, EXPT is the exit pupil position at the telephoto end, and EXPW is the exit pupil position at the wide angle end. Electronic imaging apparatus according to any one of claims 1-7, characterized in that zoom ratio of the zoom lens is 2.4 or more. Electronic imaging apparatus according to any one of claims 1-8, characterized in that the most image side surface of the most object-side surface of the first lens group is an aspherical surface. Electronic imaging apparatus according to any one of claims 1-8, characterized in that the most image side surface of the most object-side surface of the second lens group is an aspherical surface. Electronic imaging apparatus according to any one of claims 1-8, characterized in that both surfaces of the positive lens of the first lens group is an aspherical surface. Electronic imaging apparatus according to any one of claims 1-8, wherein the first lens group and all negative lenses included in the second lens group being a meniscus lens having a convex surface directed toward the object side . Electronic imaging apparatus according to any one of claims 1-8 surface on the object side of the positive lens in the second lens group which is a surface having a strong refractive power than the image-side surface. Electronic imaging apparatus according to any one of claims 1-8, wherein said negative lens of the first lens group satisfies the following condition (14).
(14) −0.3 <f _W / R ₁₁ <0.4
Where R ₁₁ is the radius of curvature near the optical axis (on the optical axis) of the first lens surface from the object side of the first lens group, and f _W is the focal length of the entire system at the wide angle end (when focusing on an object point at infinity) ). Electronic imaging apparatus according to any one of claims 1-8, wherein the first lens group satisfies the following condition (16).
(16) 0.4 <t ₁ /L<2.2
Here, t ₁ is the thickness on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the first lens group, and L is the diagonal length of the effective imaging region of the electronic imaging device. Electronic imaging apparatus according to any one of claims 1 to 15, characterized by satisfying the following condition (17).
(17) -1 <f ₁ / R ₁₁ <0.5
Here, f ₁ is the focal length of the first lens group, and R ₁₁ is the radius of curvature in the vicinity of the optical axis (on the optical axis) of the most object side surface of the first lens group. The positive lens in the first lens group is a positive meniscus lens having a positive radius of curvature in the vicinity of both sides of the optical axis (on the optical axis), and the outermost periphery of the refractive surface effective portion of each surface. The portion is an aspheric surface having a concave shape on the opposite side to the direction in which the center of curvature exists in the vicinity of the optical axis, the negative lens in the first lens group is only one lens, and the first lens group is two lenses in electronic imaging apparatus according to any one of claims 1-16, characterized by being configured. 18. The electronic imaging apparatus according to claim 17 , wherein the following conditions (18) and (19) are satisfied.
(18) −2.5 <f ₁ / R ₁₃ <−0.5
(19) -1.5 <f ₁ / R ₁₄ <0.5
Where f ₁ is the focal length of the first lens group, R ₁₃ is the radius of curvature of the object side surface of the positive meniscus lens of the first lens group, and R ₁₄ is the curvature of the image side surface of the positive meniscus lens of the first lens group. Radius. Electronic imaging apparatus according to any one of claims 1 to 18 in which the half angle omega _W at the wide-angle end of said zoom lens satisfies the following condition (20).
(20) 28 ° <ω _w <40 ° Electronic imaging apparatus according to any one of claims 1 to 19, characterized in that the open F value F _T at the telephoto end of the zoom lens satisfies the following condition (21).
(21) 2.7 <F _T <5 Electronic imaging apparatus according to any one of claims 1 to 20 in which the zoom ratio γ is characterized by satisfying the following condition (22) at the telephoto end from the wide-angle end of the zoom lens.
(22) 2 <γ <4

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