JP4884054B2 - Zoom lens - Google Patents

Description

  The present invention relates to a zoom lens, and more particularly to a zoom lens that can be thinned in the depth direction when used in an electronic imaging apparatus such as a digital camera or a video camera, and an apparatus such as an electronic imaging apparatus using the zoom lens. Is.

  In recent years, digital cameras have attracted attention as next-generation cameras that replace silver salt 35 mm film 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 type, it is aimed to provide a technology for realizing a video camera and a digital camera with a small depth while ensuring a 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. Furthermore, in order to satisfy the user's request to enjoy a wide imaging area, a zoom lens having a wide angle of view at the wide angle end and a large zoom ratio is required.

As a zoom lens with a relatively good optical performance suitable for an electronic imaging device, with a zoom ratio as large as about 5 times, a field angle at a wide angle end as large as about 60 °, and an exit pupil position appropriately set, There exists what was disclosed by patent document 1. FIG.
JP 2003-255228 A

  However, in the embodiment disclosed in Patent Document 1, since the number of lenses constituting the zoom lens is large, or the entire length of the entire zoom lens system is long, the lens barrel is sufficiently compact even if the retractable method is adopted. There was a problem of not becoming. In addition, there is a problem that the cost becomes high.

  The present invention has been made in view of such problems of the prior art, and its objectives are a large zoom ratio, a large angle of view at the wide-angle end, and it is suitable for an electronic imaging device, and further has optical performance. An object of the present invention is to provide an inexpensive zoom lens that is improved and suitable for downsizing the lens barrel.

  In order to achieve the above object, a zoom lens according to the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a negative lens group. A fourth lens group having a refractive power of 5 and a fifth lens group having a positive refractive power, and zooming is performed by changing the interval between the lens groups, and the first lens group is at the telephoto end rather than at the wide-angle end. The fifth lens group moves so as to be closer to the image side at the telephoto end than the wide-angle end, and the axial interval between the third lens group and the fourth lens group is from the wide-angle end. It is characterized by an increase at the intermediate zoom position and a decrease from the intermediate zoom position to the telephoto end.

  Hereinafter, the reason and operation of the zoom lens according to the present invention will be described.

  By adopting the configuration as described above, the burden of zooming can be shared by each lens group, so that the overall length can be shortened and the lens barrel can be easily made compact. In addition, since the exit pupil position can be maintained appropriately, the angle of incident light on the CCD of the electronic image sensor can be controlled within an appropriate range, and the light receiving surface of the electronic image sensor such as a CCD is efficient. It becomes possible to make the light incident well. Furthermore, aberration variation during zooming can be suppressed, and good optical performance can be obtained in the entire zooming range.

  This will be described in more detail below.

  In zooming from the wide-angle end to the telephoto end, the first lens group may move so that it is closer to the object side at the telephoto end than at the wide-angle end. This makes it possible to widen the zoom lens while keeping the outer diameter of the lens located closest to the object side small. Therefore, it becomes easy to achieve size reduction in the outer diameter direction of the lens barrel.

  The fifth lens group moves so as to be closer to the image side at the telephoto end than at the wide-angle end, and the axial interval between the third lens group and the fourth lens group increases from the wide-angle end to the intermediate zoom position. It is preferable to decrease from the zoom position to the telephoto end. In general, in a zoom lens including a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group, the second lens group and the second lens group Since the burden of zooming of the three lens groups is likely to increase, aberration fluctuations during zooming tend to increase. By moving the fifth lens group so that it is closer to the image side at the telephoto end than at the wide-angle end, the fifth lens group can be subjected to the zooming action, so the burden on the other zoom lens groups can be reduced. Thus, it is possible to further reduce aberration fluctuation during zooming.

  However, when the fifth lens group moves in this manner, the off-axis image surface tends to be on the plus side at the wide-angle end and the telephoto end, and on the minus side in the vicinity of the intermediate zoom state. Therefore, if the axial distance between the third lens group and the fourth lens group increases from the wide-angle end to the intermediate zoom state and decreases from the intermediate zoom state to the telephoto end, it is off-axis in the entire zoom range. The image plane position can be corrected satisfactorily.

  In the present invention, the optical system is devised as described above, and the zoom ratio is large, the angle of view at the wide-angle end is large, suitable for an electronic imaging device, good optical performance, and compact lens barrel. A zoom lens that is suitable and inexpensive is realized.

  In the present invention, in order to achieve compactness and secure good optical performance, various further improvements are added. Detailed description will be given below.

  The second lens group may move so that it is closer to the image side at the telephoto end than the wide angle end, and the third lens group may be moved so as to be closer to the object side at the telephoto end than at the wide angle end. With such a configuration, it is possible to reduce the burden of zooming of each lens group, and it is possible to suppress aberration fluctuations during zooming.

  In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a positive refractive power. It is more preferable to have a fifth lens group and perform zooming by changing the interval between the lens groups so that one or both of the following conditional expressions are satisfied.

4.00 <L _w / f _w <9.00 (1)
1.00 <L _t / f _t <1.80 (2)
Where L _w is the total length at the wide-angle end,
L _t : total length at the telephoto end,
f _w : the focal length of the entire system at the wide-angle end,
f _t : Total focal length at the telephoto end,
It is.

  These are conditional expressions relating to miniaturization of the zoom lens and securing of optical performance. If the upper limit of 9.00 of conditional expression (1) and 1.80 of the upper limit of conditional expression (2) are exceeded, the total length of the lens system becomes too long, so that the lens barrel can be made compact when retracted. It becomes difficult. If the lower limit of 4.00 of conditional expression (1) and 1.00 of the lower limit of conditional expression (2) is exceeded, the power of each lens group tends to increase, and aberration fluctuations during zooming are large. Therefore, it becomes difficult to obtain good optical performance in the entire zoom range.

  Regarding conditional expression (1), it is better to satisfy the following.

4.70 <L _w / f _w <7.70 (1) ′
Furthermore, it is better to satisfy the following.

5.30 <L _w / f _w <6.30 (1) ”
Regarding conditional expression (2), it is better to satisfy the following.

1.10 <L _t / f _t <1.75 (2) ′
Furthermore, it is better to satisfy the following.

_{1.20 <L t / f t <} 1.65 ··· (2) "
In addition, the first lens group may be composed of one positive lens. In the first lens group, the height of the off-axis light beam is the highest, so that the on-axis thickness tends to be very large when it is necessary to secure a necessary amount of the lens edge. Further, when the number of lenses of the first lens group is increased, the entrance pupil position becomes farther from the object side, so that the height of the light beam passing through the first lens group becomes higher, and the axial thickness for securing the rim thickness is further increased. Thickness is required. Naturally, the axial thickness increases as the number of lenses increases. Accordingly, as the number of lenses is increased, the size in the radial direction of the lens group and the thickness on the optical axis become larger than necessary, and the lens barrel cannot be made compact even in the retracted state. From this point of view, if the first lens group is composed of only one lens, it greatly contributes to downsizing.

  However, if the first lens group is composed of only one positive lens, the aberration generated in this lens cannot be canceled in the first lens group, so that the aberration fluctuation becomes large at the time of zooming and the optical performance. It tends to lead to deterioration. For this reason, it is necessary to suppress the occurrence of aberration in the first lens group as much as possible to a practical level where the captured image can withstand viewing. In the zoom lens of the present invention, various devices as described below are applied to ensure good optical performance.

  The positive lens of the first lens group should satisfy the following conditional expression.

75.0 <ν _d1p <105.0 (3)
Where ν _{d1p is} the Abbe number of the positive lens in the first lens group,
It is.

  If the upper limit of 105.0 of conditional expression (3) is exceeded, the availability and mass productivity of the glass material will deteriorate, leading to an increase in cost. If the lower limit of 75.0 is exceeded, the amount of chromatic aberration generated in the first lens group becomes too large, and color blurring occurs in the captured image.

  Furthermore, it is even better if the following is satisfied.

75.0 <ν _d1p <101.0 (3) ′
Furthermore, it is better to satisfy the following.

80.0 <ν _d1p <97.0 (3) ”
The positive lens in the first lens group should satisfy the following conditional expression.

−1.50 <SF _1p <−0.20 (4)
However, as defined in _{SF 1p = (R 1pf + R} 1pr) / (R 1pf -R 1pr), R 1pf, the object side surface of the positive lens of each of R _1pr the first lens group, in axial radius of curvature of the image side surface is there.

  If the upper limit of -0.20 in conditional expression (4) is exceeded, the generation of astigmatism and spherical aberration at the wide-angle end becomes too large. When the lower limit of −1.50 is exceeded, distortion at the wide-angle end becomes too large. In any case, it becomes difficult to obtain good optical performance.

  Furthermore, it is even better if the following is satisfied.

−1.10 <SF _1p <−0.32 (4) ′
Furthermore, it is better to satisfy the following.

−0.70 <SF _1p <−0.54 (4) ”
The positive lens in the first lens group is preferably a double-sided aspheric surface. Generation of distortion, astigmatism, and coma at the wide-angle end can be effectively suppressed.

  The second lens group may be configured by a negative lens L21, a negative lens L22, and a positive lens L23 in order from the object side. In this way, the rear principal point can be brought closer to the image side, so that the amount of movement during zooming can be reduced. As will be described later, the aperture stop is preferably disposed after the second lens group. In such a case, the entrance pupil can be positioned closer to the object side. Leads to a more compact design.

  Further, the negative lens L21 of the second lens group may have a concave surface facing the image side, the negative lens L22 may have a concave surface facing the object side, and the negative lens L22 and the positive lens L23 may be cemented. Since the second lens group is a lens group responsible for zooming, strong negative power is required, but large aberrations are likely to occur. When the negative lens L21 has a concave surface on the image side and the negative lens L22 has a concave surface on the object side, the off-axis aberrations such as astigmatism and coma generated in the second lens group are canceled out and suppressed to a small value. be able to. In addition, since the angle of the off-axis light beam passing through the second lens group with respect to the optical axis becomes small, the aberration fluctuation accompanying the movement of the second lens group at the time of zooming can be kept small. Furthermore, chromatic aberration can be corrected by joining the negative lens L22 and the positive lens L23 together.

  The glass material of the negative lens L21 should satisfy the following conditional expression.

1.70 <N _d21 <2.20 (5)
N _d21 is the refractive index of the negative lens L21 with respect to the d line.

  If the upper limit of 2.20 in conditional expression (5) is exceeded, the availability and mass productivity of the glass material will deteriorate, leading to an increase in cost. If the lower limit of 1.70 is exceeded, the curvature of the lens surface must be increased to obtain the desired refractive power, and astigmatism and coma tend to increase.

  Furthermore, it is even better if the following is satisfied.

1.75 <N _d21 <2.05 (5) ′
Furthermore, it is better to satisfy the following.

1.80 <N _d21 <1.90 (5) ”
The glass material of the positive lens L23 should satisfy the following conditional expression.

1.780 <N _d23 <2.100 (6)
13.0 <ν _d23 <32.0 (7)
Here, N _d23 and ν _d23 are a refractive index and an Abbe number for the d line of the positive lens L23, respectively.

  If the upper limit of 2.100 in conditional expression (6) is exceeded, the availability and mass productivity of the glass material are poor, leading to an increase in cost. If the lower limit of 1.780 is exceeded, the curvature of the lens surface must be increased to obtain the desired refractive power, and astigmatism and coma are likely to occur.

  If the upper limit of 32.0 in conditional expression (7) is exceeded, correction of chromatic aberration will be insufficient. If the lower limit of 13.0 is exceeded, correction of the secondary spectrum becomes impossible and color blurring tends to occur in the captured image.

  Regarding conditional expression (6), it is more preferable that the following is satisfied.

1.840 <N _d23 <2.020 (6) ′
Furthermore, it is better to satisfy the following.

1.900 <N _d23 <1.950 (6) ”
Regarding conditional expression (7), it is better to satisfy the following.

15.0 <ν _d23 <26.0 (7) ′
Furthermore, it is better to satisfy the following.

17.0 <ν _d23 <23.5 (7) ”
The third lens group may be composed of a positive lens and a negative lens in order from the object side. With such a configuration, the front principal point can be brought out closer to the object side, so that the amount of movement at the time of zooming can be kept small, leading to a reduction in the size of the lens system. Further, by using these as cemented lenses, axial chromatic aberration can be corrected. Further, by arranging the aspherical surface on the most object side, it is effective for correcting spherical aberration correction.

  The fourth lens group may be composed of, in order from the object side, a positive lens and a negative lens with a concave surface facing the image side. With such a configuration, the front principal point can be brought out closer to the object side, so that the amount of movement at the time of zooming can be kept small, leading to a reduction in the size of the lens system. Moreover, chromatic aberration can be corrected by joining them. The most image side surface of the fourth lens group may have a concave surface facing the image side. With this configuration, the off-axis light beam emitted from the fourth lens group can be flipped up so that the incident angle to the electronic image pickup device such as a CCD becomes an appropriate angle, and the light beam can be efficiently put into the light receiving surface.

  At this time, the glass material of the negative lens of the fourth lens group should satisfy the following conditional expression.

1.830 <N _d4n <2.100 (8)
20.0 <ν _d4n <38.0 (9)
Here, N _d4n and ν _d4n are the refractive index and Abbe number for the d-line of the negative lens in the fourth lens group, respectively.

  If the upper limit of 2.100 in conditional expression (7) is exceeded, the availability and mass productivity of the glass material are poor, leading to an increase in cost. If the lower limit of 1.830 is exceeded, the curvature of the surface must be increased in order to obtain the desired refractive power, and astigmatism and coma are likely to occur.

  If the upper limit of 38.0 in conditional expression (8) is exceeded, correction of chromatic aberration will be insufficient. If the lower limit of 20.0 is exceeded, chromatic aberration on the short wavelength side generated by this lens will be too large, and correction of the secondary spectrum of chromatic aberration will not be possible, and color blurring will tend to occur in the photographed image.

  Regarding conditional expression (8), it is better to satisfy the following.

1.890 <N _d4n <2.060 (8) ′
Furthermore, it is better to satisfy the following.

1.970 <N _d4n <2.020 (8) ”
Regarding conditional expression (9), it is better to satisfy the following.

23.0 <ν _d4n <32.0 (9) ′
Furthermore, it is better to satisfy the following.

25.0 <ν _d4n <30.0 (9) ”
The fifth lens group is preferably composed of only one positive lens. Since the fifth lens group mainly acts to move the exit pupil away from the image plane, one lens is necessary and sufficient. At this time, the positive lens of the fifth lens group should satisfy the following conditional expression.

1.750 <N _d5p <2.100 (10)
22.0 <ν _d5p <38.0 (11)
Here, N _d5p and ν _d5p are the refractive index and Abbe number for the d-line of the positive lens in the fifth lens group, respectively.

  Conditional expression (10) is a conditional expression for suppressing off-axis aberrations generated in this lens within an appropriate range, and conditional expression (11) is a conditional expression for correcting chromatic aberration of magnification. When the first lens group is configured in a small number, the lateral chromatic aberration generated in the first lens group tends to remain, but the off-axis light beam passing through the fifth lens group has a high ray height, and therefore remains in the first lens group. Convenient for correcting lateral chromatic aberration.

  If the upper limit of 2.100 in conditional expression (10) is exceeded, the availability and mass productivity of the glass material will deteriorate, leading to an increase in cost. If the lower limit of 1.750 is exceeded, the curvature of the surface must be increased in order to obtain the desired refractive power, and astigmatism and coma are likely to increase.

  If the upper limit of 38.0 in conditional expression (11) is exceeded, correction of lateral chromatic aberration will be insufficient. If the lower limit of 22.0 is exceeded, the chromatic aberration on the short wavelength side generated by this lens will be too large to perform secondary spectrum correction, and color blur will occur in the photographed image.

  Regarding conditional expression (10), it is more preferable that the following is satisfied.

1.780 <N _d5p <2.060 (10) ′
Furthermore, it is better to satisfy the following.

1.800 <N _d5p <2.020 (10) ”
Regarding conditional expression (11), it is better to satisfy the following.

23.0 <ν _d5p <32.0 (11) ′
Furthermore, it is better to satisfy the following.

24.0 <ν _d5p <29.0 (11) ”
Next, the power of each lens group constituting the zoom lens will be described.

  The first lens group should satisfy the following conditional expression.

2.50 <f ₁ / f _w <8.00 (12)
Where f _{1 is} the focal length of the first lens group,
f _w : the focal length of the entire system at the wide-angle end,
It is.

  If the upper limit of 8.00 in conditional expression (12) is exceeded, the power of the first lens group becomes too weak, the overall length of the lens system tends to be long, and it is difficult to make the lens barrel compact. If the lower limit of 2.50 is exceeded, the power becomes too strong and aberrations increase. In particular, the occurrence of chromatic aberration increases, and the color blur of the captured image becomes noticeable.

  Furthermore, it is even better if the following is satisfied.

3.00 <f ₁ / f _w <5.00 (12) ′
Furthermore, it is better to satisfy the following.

3.50 <f ₁ / f _w <4.20 (12) ”
The second lens group should satisfy the following conditional expression.

-2.10 <f ₂ / f _w <−0.05 (13)
Where f _{2 is} the focal length of the second lens group,
f _w : the focal length of the entire system at the wide-angle end,
It is.

  If the lower limit of -2.10 of the conditional expression (13) is exceeded, the power of the second lens group becomes too weak, and the amount of movement for zooming becomes large, making it difficult to make the lens barrel compact. When the upper limit of −0.05 is exceeded, the paraxial imaging magnification of the second lens group decreases, the amount of movement for zooming also increases, and aberration correction becomes difficult.

  Furthermore, it is even better if the following is satisfied.

−1.70 <f ₂ / f _w <−0.07 (13) ′
Furthermore, it is better to satisfy the following.

−1.30 <f ₂ / f _w <−0.09 (13) ”
The third lens group should satisfy the following conditional expression.

1.40 <f ₃ / f _w <2.80 (14)
Where f _{3 is} the focal length of the third lens group,
f _w : the focal length of the entire system at the wide-angle end,
It is.

  If the upper limit of 2.80 in conditional expression (14) is exceeded, the power of the third lens group becomes too weak, and the amount of movement for zooming increases, making it difficult to make the lens barrel compact. When the lower limit of 1.40 is exceeded, the paraxial imaging magnification of the third lens group becomes small, the amount of movement for zooming also becomes large, and aberration correction becomes difficult.

  Furthermore, it is even better if the following is satisfied.

1.60 <f ₃ / f _w <2.30 (14) ′
Furthermore, it is better to satisfy the following.

1.78 <f ₃ / f _w <1.93 (14) ”
The fourth lens group should satisfy the following conditional expression.

−9.00 <f ₄ / f _w <−5.80 (15)
Where f _{4 is} the focal length of the fourth lens group,
f _w : the focal length of the entire system at the wide-angle end,
It is.

  If the lower limit of −9.00 of conditional expression (15) is exceeded, the power of the fourth lens group becomes too weak, and the angle of incidence of light on an electronic imaging device such as a CCD becomes large. Then, the shading of the brightness around the screen tends to occur, which is not preferable. If the upper limit of −5.80 is exceeded, the power of the fourth group becomes too strong, and the occurrence of aberrations tends to increase.

  Furthermore, it is even better if the following is satisfied.

−8.00 <f ₄ / f _w <−6.20 (15) ′
Furthermore, it is better to satisfy the following.

−7.30 <f ₄ / f _w <−6.60 (15) ”
The fifth lens group should satisfy the following conditional expression:

1.10 <f ₅ / f _w <3.00 (16)
Where f _{5 is} the focal length of the fifth lens group,
f _w : the focal length of the entire system at the wide-angle end,
It is.

  If the upper limit of 3.00 to conditional expression (16) is exceeded, the power of the fifth lens group becomes too weak, and the angle of incidence of light on an electronic imaging device such as a CCD becomes large. Then, the shading of the brightness around the screen tends to occur, which is not preferable. If the lower limit of 1.10 is exceeded, the power of the fifth lens group becomes too strong, and the aberration fluctuations when focusing with the fifth lens group become large, making it difficult to obtain a good image during close-up shooting.

  Furthermore, it is even better if the following is satisfied.

1.40 <f ₅ / f _w <2.55 (16) ′
Furthermore, it is better to satisfy the following.

1.70 <f ₅ / f _w <2.05 (16) ”
Next, the aperture stop and the shutter are preferably arranged between the second lens group and the third lens group. In this way, the height of the off-axis light beam passing through the third lens group and the subsequent lens does not need to be higher than necessary, so that the fluctuations in off-axis aberrations when the lens group after the third lens group moves during zooming are reduced. Can be suppressed. Further, it is preferable to move it together with the third lens group at the time of zooming. In this way, the entrance pupil can be made shallow when viewed from the object side, and the exit pupil can be made far from the image plane. Further, since the height of the off-axis light beam is lowered, the shutter unit does not need to be enlarged, and the dead space when moving the aperture stop and the shutter can be reduced.

  Focusing on the closest object point may be an inner focus by the fourth lens group or the fifth lens group. The inner focus method has a lighter moving lens group compared to the entire extension method and the focus by the first lens group extension, so the load on the motor is less, the total length does not increase, and the drive motor can be placed inside the lens frame This is advantageous for downsizing because the radial direction of the lens frame does not increase. In particular, when the focusing method using the fifth lens group is used, fluctuations in the off-axis image plane can be reduced, so that good optical performance can be ensured up to the periphery of the screen even when shooting an object at a close distance.

  When distortion of the zoom lens according to the present invention is allowed to occur, the height of the incident light on the surface closest to the object side becomes lower for the angle of view, so the outer diameter of the lens positioned closest to the object side can be reduced. It is. Therefore, the function of changing the shape by intentionally generating barrel distortion and processing the image data obtained by picking up the image formed through the zoom lens with an electronic image pickup device is used. It is preferable that the image distortion due to distortion generated in the system is corrected so that the image can be observed. In particular, it is ideal to output image data that has already been corrected from an electronic imaging device such as a camera. Regarding the optical system, it is preferable that the following conditional expression is satisfied with respect to the distortion aberration of the zoom lens when focusing on an object point at approximately infinity.

_{0.850 <y 07 / (f w} · tanω 07w) <0.970 ··· (17)
However, if the distance (maximum image height) from the center to the farthest point in the effective imaging plane (in the plane where imaging is possible) of the electronic imaging device is y ₁₀ , y ₀₇ = 0.7 y ₁₀ and ω _07w are at the wide-angle end. Is an angle with respect to the optical axis in the object direction corresponding to the image point connected to the position of _y07 from the center on the effective imaging surface of the electronic imaging device.

  A value of around 1 exceeding the upper limit of 0.970 in conditional expression (17) is equivalent to a good correction of distortion aberration optically, but a wide viewing angle while maintaining a compact optical system. It becomes difficult to capture as an image. If the lower limit of 0.850 is exceeded, when image distortion due to distortion of the optical system is corrected by image processing, the enlargement magnification in the radial direction at the periphery of the angle of view becomes too high and the image sharpness at the periphery of the image becomes low. Deterioration becomes noticeable.

  In addition, it is better to satisfy the following.

0.880 <y ₀₇ / (f _w tan ω _07w ) <0.960 (17) ′
Furthermore, it is best to satisfy the following.

_{0.910 <y 07 / (f w} · tanω 07w) <0.950 ··· (17) "
Each of the above-described configurations may arbitrarily satisfy a plurality at the same time, whereby a better effect can be obtained.

  Further, if each conditional expression is satisfied by being arbitrarily combined, a better effect can be obtained.

  The zoom lens of the present invention described above can be configured as an electronic image pickup apparatus by including an image pickup element disposed at a position for receiving an object image formed by the zoom lens.

  In addition, the zoom lens of the present invention described above includes an image sensor disposed at a position for receiving an object image formed by the zoom lens, a CPU that processes an electronic signal photoelectrically converted by the image sensor, and an operator. Including an input unit for inputting an information signal desired to be input to the CPU, display processing means for displaying an output from the CPU on a display device (for example, LCD), and a recording medium for recording the output from the CPU. Can be configured as an information processing apparatus configured to display an object image received by an image sensor with a zoom lens on a display device.

  In this case, the information processing apparatus includes a mobile terminal device (for example, a mobile phone or a PDA).

  In addition, the zoom lens of the present invention described above includes an image sensor disposed at a position for receiving an object image formed by the zoom lens, a CPU that processes an electronic signal photoelectrically converted by the image sensor, and an image of the image sensor. A display element that displays the object image received by the element so as to be observable, and a recording medium for recording image information of the object image received by the image sensor (for example, a memory card or DVD ± RW in a memory) ), And a display processing unit that displays an object image received by the image sensor on the display element, and a recording processing unit that records the object image received by the image sensor on a recording medium Can be configured as an electronic camera device.

  As described above, according to the present invention, the zoom ratio is large, the angle of view at the wide-angle end is large, suitable for an electronic imaging device, optical performance is further improved, and it is suitable for downsizing of the lens barrel, An inexpensive zoom lens can be provided.

  Examples 1 to 6 of the zoom lens according to the present invention will be described below. FIGS. 1 to 6 show lens cross-sectional views of the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity in Examples 1 to 6, respectively. In the figure, the first lens group is G1, the second lens group is G2, the aperture stop is S, the third lens group is G3, the fourth lens group is G4, the fifth lens group is G5, and an IR cut coat is applied. A parallel plate constituting a filter or the like is indicated by F, a parallel plate of a cover glass of an electronic image sensor (CCD or CMOS) is indicated by C, and an image plane (light receiving surface of the electronic image sensor) is indicated by I. In addition, you may give the multilayer film for a wavelength range restriction | limiting to the surface of the cover glass C. FIG. Further, the cover glass C may have a low-pass filter action.

  As shown in FIG. 1, the zoom optical system according to the first embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, and a first lens unit having a positive refractive power. 3 lens group G3, 4th lens group G4 of negative refracting power, and 5th lens group G5 of positive refracting power, and when changing magnification from the wide angle end to the telephoto end, the first lens group G1 The second lens group G2 moves slightly toward the object side from the wide-angle end to the intermediate state, moves toward the image side from the intermediate state to the telephoto end, and moves toward the image side from the position of the wide-angle end at the telephoto end. To position. The aperture stop S and the third lens group G3 move monotonously to the object side while integrally reducing the distance between the first lens group G2. The fourth lens group G4 moves toward the object side while widening the distance from the third lens group G3 from the wide-angle end to the intermediate state and narrowing from the intermediate state to the telephoto end. The fifth lens group G5 moves to the image side.

  In order from the object side, the first lens group G1 includes one biconvex positive lens, the second lens group G2 includes a biconcave negative lens, and a cemented lens of a biconcave negative lens and a biconvex positive lens. The third lens group G3 includes a cemented lens of a biconvex positive lens and a negative meniscus lens having a convex surface facing the image side, and the fourth lens group G4 has a positive meniscus lens having a convex surface facing the object side and a convex surface facing the object side. The fifth lens group G5 is composed of a single biconvex positive lens. The aperture stop S is integrally located on the object side of the third lens group G3.

  The aspheric surfaces are both surfaces of the biconvex positive lens of the first lens group G1, both surfaces of the biconcave negative lens of the second lens group G2, the most object side surface of the cemented lens of the third lens group G3, and the fourth lens group G4. Are used on the six surfaces closest to the object side.

  As shown in FIG. 2, the zoom optical system according to the second embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, and a first lens unit having a positive refractive power. 3 lens group G3, 4th lens group G4 of negative refracting power, and 5th lens group G5 of positive refracting power, and when changing magnification from the wide angle end to the telephoto end, the first lens group G1 The second lens group G2 moves slightly toward the object side from the wide-angle end to the intermediate state, moves toward the image side from the intermediate state to the telephoto end, and moves toward the image side from the position of the wide-angle end at the telephoto end. To position. The aperture stop S and the third lens group G3 move monotonously to the object side while integrally reducing the distance between the first lens group G2. The fourth lens group G4 moves toward the object side while widening the distance from the third lens group G3 from the wide-angle end to the intermediate state and narrowing from the intermediate state to the telephoto end. The fifth lens group G5 moves to the image side.

  In order from the object side, the first lens group G1 includes one biconvex positive lens, the second lens group G2 includes a biconcave negative lens, and a cemented lens of a biconcave negative lens and a biconvex positive lens. The third lens group G3 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, the fourth lens group G4 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, and the fifth lens group G5 is It consists of one biconvex positive lens. The aperture stop S is integrally located on the object side of the third lens group G3.

  The aspherical surfaces are both surfaces of the biconvex positive lens of the first lens group G1, both surfaces of the biconcave negative lens of the second lens group G2, and the most object side surface and the most image side surface of the cemented lens of the third lens group G3. It is used for 6 sides.

  As shown in FIG. 3, the zoom optical system according to the third embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, and a first lens unit having a positive refractive power. 3 lens group G3, 4th lens group G4 of negative refracting power, and 5th lens group G5 of positive refracting power, and when changing magnification from the wide angle end to the telephoto end, the first lens group G1 The second lens group G2 moves slightly toward the object side from the wide-angle end to the intermediate state, moves toward the image side from the intermediate state to the telephoto end, and moves toward the image side from the position of the wide-angle end at the telephoto end. To position. The aperture stop S and the third lens group G3 move monotonously to the object side while integrally reducing the distance between the first lens group G2. The fourth lens group G4 moves toward the object side while widening the distance from the third lens group G3 from the wide-angle end to the intermediate state and narrowing from the intermediate state to the telephoto end. The fifth lens group G5 moves to the image side.

  In order from the object side, the first lens group G1 includes one biconvex positive lens, the second lens group G2 includes a biconcave negative lens, and a cemented lens of a biconcave negative lens and a biconvex positive lens. The third lens group G3 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, the fourth lens group G4 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, and the fifth lens group G5 is It consists of one biconvex positive lens. The aperture stop S is integrally located on the object side of the third lens group G3.

  The aspherical surfaces are both surfaces of the biconvex positive lens of the first lens group G1, both surfaces of the biconcave negative lens of the second lens group G2, and the most object side surface and the most image side surface of the cemented lens of the third lens group G3. It is used for 6 sides.

  As shown in FIG. 4, the zoom optical system according to the fourth embodiment includes, in order from the object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, an aperture stop S, and a first lens unit having a positive refractive power. 3 lens group G3, 4th lens group G4 of negative refracting power, and 5th lens group G5 of positive refracting power, and when changing magnification from the wide angle end to the telephoto end, the first lens group G1 Moving to the object side, the second lens group G2 moves to the image side. The aperture stop S and the third lens group G3 move monotonously to the object side while integrally reducing the distance between the first lens group G2. The fourth lens group G4 moves toward the object side while widening the distance from the third lens group G3 from the wide-angle end to the intermediate state and narrowing from the intermediate state to the telephoto end. The fifth lens group G5 moves to the image side.

  In order from the object side, the first lens group G1 includes one biconvex positive lens, the second lens group G2 includes a biconcave negative lens, and a cemented lens of a biconcave negative lens and a biconvex positive lens. The third lens group G3 includes a cemented lens of a biconvex positive lens and a biconcave negative lens. The fourth lens group G4 includes a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side. The fifth lens group G5 is composed of a cemented lens, and is composed of one biconvex positive lens. The aperture stop S is integrally located on the object side of the third lens group G3.

  The aspherical surfaces are both surfaces of the biconvex positive lens of the first lens group G1, both surfaces of the biconcave negative lens of the second lens group G2, and the most object side surface and the most image side surface of the cemented lens of the third lens group G3. It is used for 6 sides.

  As shown in FIG. 5, the zoom optical system according to the fifth embodiment includes, in order from the object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, an aperture stop S, and a first lens unit having a positive refractive power. 3 lens group G3, 4th lens group G4 of negative refracting power, and 5th lens group G5 of positive refracting power, and when changing magnification from the wide angle end to the telephoto end, the first lens group G1 The second lens group G2 moves slightly toward the object side from the wide-angle end to the intermediate state, moves toward the image side from the intermediate state to the telephoto end, and moves toward the image side from the position of the wide-angle end at the telephoto end. To position. The aperture stop S and the third lens group G3 move monotonously to the object side while integrally reducing the distance between the first lens group G2. The fourth lens group G4 moves toward the object side while widening the distance from the third lens group G3 from the wide-angle end to the intermediate state and narrowing from the intermediate state to the telephoto end. The fifth lens group G5 moves to the image side.

  In order from the object side, the first lens group G1 includes one biconvex positive lens, the second lens group G2 includes a biconcave negative lens, and a cemented lens of a biconcave negative lens and a biconvex positive lens. The third lens group G3 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, the fourth lens group G4 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, and the fifth lens group G5 is It consists of one biconvex positive lens. The aperture stop S is integrally located on the object side of the third lens group G3.

  The aspherical surfaces are both surfaces of the biconvex positive lens of the first lens group G1, both surfaces of the biconcave negative lens of the second lens group G2, and the most object side surface and the most image side surface of the cemented lens of the third lens group G3. It is used for 6 sides.

  As shown in FIG. 6, the zoom optical system according to the sixth embodiment includes, in order from the object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, an aperture stop S, and a first lens unit having a positive refractive power. 3 lens group G3, 4th lens group G4 of negative refracting power, and 5th lens group G5 of positive refracting power, and when changing magnification from the wide angle end to the telephoto end, the first lens group G1 The second lens group G2 moves slightly toward the object side from the wide-angle end to the intermediate state, moves toward the image side from the intermediate state to the telephoto end, and moves toward the image side from the position of the wide-angle end at the telephoto end. To position. The aperture stop S and the third lens group G3 move monotonously to the object side while integrally reducing the distance between the first lens group G2. The fourth lens group G4 moves toward the object side while widening the distance from the third lens group G3 from the wide-angle end to the intermediate state and narrowing from the intermediate state to the telephoto end. The fifth lens group G5 moves to the image side.

  In order from the object side, the first lens group G1 includes one biconvex positive lens, the second lens group G2 includes a biconcave negative lens, and a cemented lens of a biconcave negative lens and a biconvex positive lens. The third lens group G3 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, the fourth lens group G4 is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens, and the fifth lens group G5 is It consists of one biconvex positive lens. The aperture stop S is integrally located on the object side of the third lens group G3.

  The aspherical surfaces are both surfaces of the biconvex positive lens of the first lens group G1, both surfaces of the biconcave negative lens of the second lens group G2, and the most object side surface and the most image side surface of the cemented lens of the third lens group G3. It is used for 6 sides.

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 formula, 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 = 13.131 (aspherical surface) d ₁ = 3.17 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = -145.288 (aspherical surface) d ₂ = (variable)
r ₃ = -37.836 (aspherical surface) d ₃ = 0.80 n _d2 = 1.80610 ν _d2 = 40.92
r ₄ = 9.350 (aspherical surface) d ₄ = 2.19
r ₅ = -8.965 d ₅ = 0.70 n _d3 = 1.58913 ν _d3 = 61.14
r ₆ = 29.209 d ₆ = 1.48 n _d4 = 1.92286 ν _d4 = 18.90
r ₇ = -28.126 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.37
r ₉ = 17.925 (aspherical surface) d ₉ = 1.59 n _d5 = 1.77377 ν _d5 = 47.17
r ₁₀ = -6.800 d ₁₀ = 0.61 n _d6 = 1.78472 ν _d6 = 25.68
r ₁₁ = -19.935 d ₁₁ = (variable)
r ₁₂ = 4.410 (aspherical surface) d ₁₂ = 1.97 n _d7 = 1.76802 ν _d7 = 49.24
r ₁₃ = 11.157 d ₁₃ = 0.51 n _d8 = 2.00069 ν _d8 = 25.46
r ₁₄ = 3.550 d ₁₄ = (variable)
r ₁₅ = 41.001 d ₁₅ = 2.35 n _d9 = 1.80518 ν _d9 = 25.42
r ₁₆ = -14.105 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d10 = 1.54771 ν _d10 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d11 = 1.51633 ν _d11 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.60
r ₂₁ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -2.41125 × 10 ^-5
A ₆ = -3.21539 × 10 ^-7
A ₈ = 0
A ₁₀ = 0
Second side K = 0.000
A ₄ = -6.80953 × 10 ^-6
A ₆ = -3.70482 × 10 ^-8
A ₈ = 0
A ₁₀ = 0
Third side K = 0.000
A ₄ = 3.50640 × 10 ^-4
A ₆ = -4.49378 × 10 ^-6
A ₈ = 1.59282 × 10 ^-7
A ₁₀ = -2.37981 × 10 ^-9
4th surface K = -1.061
A ₄ = 3.44906 × 10 ^-4
A ₆ = 1.17809 × 10 ^-5
A ₈ = -2.58210 × 10 ^-7
A ₁₀ = 2.30813 × 10 ^-8
9th surface K = 0.748
A ₄ = -6.22558 × 10 ^-5
A ₆ = 2.61058 × 10 ^-7
A ₈ = 2.30167 × 10 ^-7
A ₁₀ = -1.23545 × 10 ^-7
Surface 12 K = -0.044
A ₄ = -1.42650 × 10 ^-4
A ₆ = 1.82011 × 10 ^-6
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 6.62 14.58 31.74
F _NO 3.31 4.38 5.16
2ω (°) 68.01 29.91 13.95
d ₂ 0.57 5.03 9.28
d ₇ 11.18 6.03 0.43
d ₁₁ 0.38 2.69 0.22
d ₁₄ 3.34 7.88 13.49
d ₁₆ 4.54 3.23 2.28.

Example 2
r ₁ = 13.726 (aspherical surface) d ₁ = 3.17 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = -85.837 (aspherical surface) d ₂ = (variable)
r ₃ = -38.043 (aspherical surface) d ₃ = 0.80 n _d2 = 1.80610 ν _d2 = 40.92
r ₄ = 9.226 (aspherical surface) d ₄ = 2.19
r ₅ = -9.230 d ₅ = 0.70 n _d3 = 1.58913 ν _d3 = 61.14
r ₆ = 25.936 d ₆ = 1.48 n _d4 = 1.92286 ν _d4 = 18.90
r ₇ = -36.175 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.37
r ₉ = 7.800 (aspherical surface) d ₉ = 2.22 n _d5 = 1.77377 ν _d5 = 47.17
r ₁₀ = -6.800 d ₁₀ = 0.61 n _d6 = 1.68893 ν _d6 = 31.16
r ₁₁ = 20.470 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 5.311 d ₁₂ = 2.07 n _d7 = 1.88300 ν _d7 = 40.76
r ₁₃ = -1158.189 d ₁₃ = 0.51 n _d8 = 2.00069 ν _d8 = 25.46
r ₁₄ = 4.141 d ₁₄ = (variable)
r ₁₅ = 30.007 d ₁₅ = 2.35 n _d9 = 1.80518 ν _d9 = 25.42
r ₁₆ = -14.743 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d10 = 1.54771 ν _d10 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d11 = 1.51633 ν _d11 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.60
r ₂₁ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -1.82405 × 10 ^-5
A ₆ = -2.53266 × 10 ^-7
A ₈ = 0
A ₁₀ = 0
Second side K = 0.000
A ₄ = 6.18637 × 10 ^-6
A ₆ = -6.21578 × 10 ^-8
A ₈ = 0
A ₁₀ = 0
Third side K = 0.000
A ₄ = 3.72444 × 10 ^-4
A ₆ = -4.17444 × 10 ^-6
A ₈ = 8.99176 × 10 ^-8
A ₁₀ = -1.56083 × 10 ^-9
4th surface K = -1.570
A ₄ = 5.05344 × 10 ^-4
A ₆ = 1.07045 × 10 ^-5
A ₈ = 8.83402 × 10 ^-9
A ₁₀ = 8.19063 × 10 ^-9
Surface 9 K = -0.939
A ₄ = 7.47118 × 10 ^-4
A ₆ = 1.87059 × 10 ^-5
A ₈ = -5.14211 × 10 ^-7
A ₁₀ = -8.51175 × 10 ^-8
11th surface K = 0.000
A ₄ = 1.47264 × 10 ^-3
A ₆ = 4.28950 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 6.62 14.22 31.73
F _NO 3.41 4.35 5.02
2ω (°) 67.57 30.38 13.84
d ₂ 0.57 5.04 9.51
d ₇ 11.02 6.00 0.43
d ₁₁ 0.40 2.60 0.22
d ₁₄ 3.33 6.79 11.99
d ₁₆ 4.05 3.45 2.87.

Example 3
r ₁ = 12.998 (aspherical surface) d ₁ = 3.45 n _d1 = 1.43875 ν _d1 = 94.93
r ₂ = -56.964 (aspherical surface) d ₂ = (variable)
r ₃ = -29.930 (aspherical surface) d ₃ = 0.80 n _d2 = 1.80610 ν _d2 = 40.92
r ₄ = 9.186 (aspherical surface) d ₄ = 2.19
r ₅ = -9.158 d ₅ = 0.70 n _d3 = 1.58913 ν _d3 = 61.14
r ₆ = 27.313 d ₆ = 1.48 n _d4 = 1.92286 ν _d4 = 18.90
r ₇ = -29.143 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.37
r ₉ = 7.800 (aspherical surface) d ₉ = 2.20 n _d5 = 1.77377 ν _d5 = 47.17
r ₁₀ = -6.800 d ₁₀ = 0.61 n _d6 = 1.68893 ν _d6 = 31.16
r ₁₁ = 20.540 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 5.367 d ₁₂ = 2.08 n _d7 = 1.88300 ν _d7 = 40.76
r ₁₃ = -114.106 d ₁₃ = 0.51 n _d8 = 2.00069 ν _d8 = 25.46
r ₁₄ = 4.180 d ₁₄ = (variable)
r ₁₅ = 28.481 d ₁₅ = 2.35 n _d9 = 1.80518 ν _d9 = 25.42
r ₁₆ = -14.752 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d10 = 1.54771 ν _d10 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d11 = 1.51633 ν _d11 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.62
r ₂₁ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -2.35458 × 10 ^-5
A ₆ = -2.41873 × 10 ^-7
A ₈ = 0
A ₁₀ = 0
Second side K = 0.000
A ₄ = 1.27194 × 10 ^-5
A ₆ = -1.28219 × 10 ^-8
A ₈ = 0
A ₁₀ = 0
Third side K = 0.000
A ₄ = 3.93377 × 10 ^-4
A ₆ = -4.71194 × 10 ^-6
A ₈ = 7.44028 × 10 ^-8
A ₁₀ = -1.26789 × 10 ^-9
4th surface K = -0.854
A ₄ = 3.85073 × 10 ^-4
A ₆ = 1.09184 × 10 ^-5
A ₈ = -6.06903 × 10 ^-9
A ₁₀ = 3.00577 × 10 ^-9
The ninth side K = -0.890
A ₄ = 7.37916 × 10 ^-4
A ₆ = 1.63555 × 10 ^-5
A ₈ = -1.04707 × 10 ^-7
A ₁₀ = -1.09038 × 10 ^-7
11th surface K = 0.000
A ₄ = 1.45721 × 10 ^-3
A ₆ = 4.23048 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 6.62 14.42 31.74
F _NO 3.41 4.35 4.88
2ω (°) 67.98 30.01 13.77
d ₂ 0.57 5.41 10.11
d ₇ 10.77 5.89 0.43
d ₁₁ 0.47 2.62 0.25
d ₁₄ 3.35 6.91 11.39
d ₁₆ 4.04 3.32 2.52.

Example 4
r ₁ = 14.006 (aspherical surface) d ₁ = 3.21 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = -63.961 (aspherical surface) d ₂ = (variable)
r ₃ = -62.128 (aspherical surface) d ₃ = 0.80 n _d2 = 1.80610 ν _d2 = 40.92
r ₄ = 8.732 (aspherical surface) d ₄ = 2.19
r ₅ = -9.634 d ₅ = 0.71 n _d3 = 1.69680 ν _d3 = 55.53
r ₆ = 27.040 d ₆ = 1.51 n _d4 = 1.92286 ν _d4 = 18.90
r ₇ = -27.632 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.37
r ₉ = 7.059 (aspherical surface) d ₉ = 2.61 n _d5 = 1.77377 ν _d5 = 47.17
r ₁₀ = -5.168 d ₁₀ = 0.60 n _d6 = 1.68893 ν _d6 = 31.16
r ₁₁ = 13.827 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 5.051 d ₁₂ = 1.62 n _d7 = 1.81600 ν _d7 = 46.62
r ₁₃ = 12.402 d ₁₃ = 0.50 n _d8 = 2.00069 ν _d8 = 25.46
r ₁₄ = 4.165 d ₁₄ = (variable)
r ₁₅ = 38.360 d ₁₅ = 2.35 n _d9 = 2.00069 ν _d9 = 25.46
r ₁₆ = -17.347 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d10 = 1.54771 ν _d10 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d11 = 1.51633 ν _d11 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.61
r ₂₁ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -1.80006 × 10 ^-5
A ₆ = -1.32046 × 10 ^-7
A ₈ = 0
A ₁₀ = 0
Second side K = 0.000
A ₄ = 1.72341 × 10 ^-5
A ₆ = -4.04260 × 10 ^-8
A ₈ = 0
A ₁₀ = 0
Third side K = 0.000
A ₄ = 3.30809 × 10 ^-4
A ₆ = -6.93335 × 10 ^-6
A ₈ = 1.83679 × 10 ^-7
A ₁₀ = -2.54736 × 10 ^-9
4th surface K = -1.404
A ₄ = 5.12084 × 10 ^-4
A ₆ = 2.34364 × 10 ^-6
A ₈ = 2.19326 × 10 ^-7
A ₁₀ = 1.22205 × 10 ^-9
Surface 9 K = -3.142
A ₄ = 1.44837 × 10 ^-3
A ₆ = -1.26704 × 10 ^-5
A ₈ = 5.36646 × 10 ^-7
A ₁₀ = -1.42543 × 10 ^-7
11th surface K = 0.000
A ₄ = 1.60777 × 10 ^-3
A ₆ = 4.12926 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 6.61 14.94 31.74
F _NO 3.37 4.23 5.00
2ω (°) 65.48 28.47 13.73
d ₂ 0.57 5.62 9.27
d ₇ 10.77 5.68 0.43
d ₁₁ 0.48 1.92 0.15
d ₁₄ 3.35 7.18 12.47
d ₁₆ 4.23 3.63 2.68.

Example 5
r ₁ = 14.666 (aspherical surface) d ₁ = 3.20 n _d1 = 1.43875 ν _d1 = 94.93
r ₂ = -54.521 (aspherical surface) d ₂ = (variable)
r ₃ = -38.229 (Aspherical surface) d ₃ = 0.80 n _d2 = 1.80610 ν _d2 = 40.92
r ₄ = 9.630 (aspherical surface) d ₄ = 2.19
r ₅ = -8.740 d ₅ = 0.70 n _d3 = 1.58913 ν _d3 = 61.14
r ₆ = 32.581 d ₆ = 1.48 n _d4 = 1.92286 ν _d4 = 18.90
r ₇ = -27.615 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.37
r ₉ = 7.800 (aspherical surface) d ₉ = 2.57 n _d5 = 1.77377 ν _d5 = 47.17
r ₁₀ = -6.800 d ₁₀ = 0.61 n _d6 = 1.68893 ν _d6 = 31.16
r ₁₁ = 19.246 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 5.370 d ₁₂ = 2.06 n _d7 = 1.88300 ν _d7 = 40.76
r ₁₃ = -129.784 d ₁₃ = 0.51 n _d8 = 2.00069 ν _d8 = 25.46
r ₁₄ = 4.191 d ₁₄ = (variable)
r ₁₅ = 20.499 d ₁₅ = 2.35 n _d9 = 1.80518 ν _d9 = 25.42
r ₁₆ = -17.739 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d10 = 1.54771 ν _d10 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d11 = 1.51633 ν _d11 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.61
r ₂₁ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -1.81359 × 10 ^-5
A ₆ = -1.31494 × 10 ^-7
A ₈ = 0
A ₁₀ = 0
Second side K = 0.000
A ₄ = 1.01441 × 10 ^-5
A ₆ = -3.08880 × 10 ^-9
A ₈ = 0
A ₁₀ = 0
Third side K = 0.000
A ₄ = 2.78275 × 10 ^-4
A ₆ = -3.87019 × 10 ^-6
A ₈ = 1.47604 × 10 ^-7
A ₁₀ = -2.32474 × 10 ^-9
4th surface K = -0.584
A ₄ = 2.50636 × 10 ^-4
A ₆ = 2.47399 × 10 ^-6
A ₈ = 2.47163 × 10 ^-7
A ₁₀ = 4.96916 × 10 ^-9
Surface 9 K = -0.811
A ₄ = 5.56562 × 10 ^-4
A ₆ = 1.18629 × 10 ^-5
A ₈ = -2.52008 × 10 ^-7
A ₁₀ = -2.82755 × 10 ^-8
11th surface K = 0.000
A ₄ = 1.25468 × 10 ^-3
A ₆ = 3.36566 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 6.61 14.27 31.75
F _NO 2.80 3.58 3.91
2ω (°) 67.73 29.93 13.57
d ₂ 0.57 6.16 11.61
d ₇ 10.77 6.27 0.43
d ₁₁ 0.38 2.63 0.28
d ₁₄ 3.32 6.97 11.00
d ₁₆ 4.04 3.21 2.75.

Example 6
r ₁ = 14.558 (aspherical surface) d ₁ = 3.24 n _d1 = 1.43875 ν _d1 = 94.93
r ₂ = -52.051 (aspherical surface) d ₂ = (variable)
r ₃ = -44.850 (aspherical surface) d ₃ = 0.80 n _d2 = 1.88300 ν _d2 = 40.76
r ₄ = 9.992 (aspherical surface) d ₄ = 2.19
r ₅ = -8.538 d ₅ = 0.70 n _d3 = 1.58913 ν _d3 = 61.14
r ₆ = 35.581 d ₆ = 1.47 n _d4 = 1.92286 ν _d4 = 18.90
r ₇ = -25.525 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.37
r ₉ = 7.800 (aspherical surface) d ₉ = 2.60 n _d5 = 1.77377 ν _d5 = 47.17
r ₁₀ = -6.800 d ₁₀ = 0.60 n _d6 = 1.68893 ν _d6 = 31.16
r ₁₁ = 19.250 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 5.360 d ₁₂ = 2.10 n _d7 = 1.88300 ν _d7 = 40.76
r ₁₃ = -93.009 d ₁₃ = 0.50 n _d8 = 2.00069 ν _d8 = 25.46
r ₁₄ = 4.176 d ₁₄ = (variable)
r ₁₅ = 20.185 d ₁₅ = 2.35 n _d9 = 1.80518 ν _d9 = 25.42
r ₁₆ = -18.062 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d10 = 1.54771 ν _d10 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d11 = 1.51633 ν _d11 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.60
r ₂₁ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -1.83244 × 10 ^-5
A ₆ = -1.28024 × 10 ^-7
A ₈ = 0
A ₁₀ = 0
Second side K = 0.000
A ₄ = 1.21730 × 10 ^-5
A ₆ = -3.83119 × 10 ^-9
A ₈ = 0
A ₁₀ = 0
Third side K = 0.000
A ₄ = 2.39553 × 10 ^-4
A ₆ = -2.82074 × 10 ^-6
A ₈ = 1.20596 × 10 ^-7
A ₁₀ = -2.14299 × 10 ^-9
4th surface K = -0.619
A ₄ = 2.24098 × 10 ^-4
A ₆ = 1.75073 × 10 ^-6
A ₈ = 3.08030 × 10 ^-7
A ₁₀ = -6.71731 × 10 ^-10
Surface 9 K = -0.785
A ₄ = 5.49617 × 10 ^-4
A ₆ = 1.15403 × 10 ^-5
A ₈ = -2.60160 × 10 ^-7
A ₁₀ = -2.62162 × 10 ^-8
11th surface K = 0.000
A ₄ = 1.25458 × 10 ^-3
A ₆ = 3.33752 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 6.61 14.22 31.76
F _NO 2.80 3.57 3.89
2ω (°) 67.64 29.95 13.54
d ₂ 0.57 6.12 11.47
d ₇ 10.66 6.30 0.43
d ₁₁ 0.39 2.63 0.29
d ₁₄ 3.32 6.96 10.94
d ₁₆ 4.06 3.22 2.83.

  Aberration diagrams at the time of focusing on an object point at infinity in Examples 1 to 6 are shown in FIGS. In these aberration diagrams, (a) is a wide-angle end, (b) is an intermediate state, and (c) is spherical aberration, astigmatism, distortion, and lateral chromatic aberration at a telephoto end. In each figure, “FIY” indicates the maximum image height.

  Next, the values of conditional expressions (1) to (17) in the above-described embodiments will be shown.

Conditional Example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 (1) 5.720 5.727 5.752 5.745 5.750 5.753
(2) 1.371 1.373 1.372 1.373 1.418 1.416
(3) 81.540 81.540 94.930 81.540 94.930 94.930
(4) -0.834 -0.724 -0.628 -0.641 -0.576 -0.563
(5) 1.806 1.806 1.806 1.806 1.806 1.883
(6) 1.923 1.923 1.923 1.923 1.923 1.923
(7) 40.920 40.920 40.920 40.920 40.920 40.760
(8) 2.001 2.001 2.001 2.001 2.001 2.001
(9) 25.458 25.458 25.458 25.458 25.458 25.458
(10) 1.805 1.805 1.805 2.001 1.805 1.805
(11) 25.420 25.420 25.420 25.458 25.420 25.420
(12) 3.686 3.633 3.702 3.546 4.040 3.983
(13) -1.190 -1.122 -1.133 -1.117 -1.192 -1.172
(14) 1.915 1.842 1.842 1.806 1.875 1.876
(15) -6.712 -7.112 -6.768 -7.246 -6.814 -6.850
(16) 2.008 1.898 1.870 1.845 1.836 1.842
(17) 0.923 0.926 0.924 0.943 0.928 0.929
The zoom lens according to the present invention as described above is used in an imaging apparatus that forms an object image with the imaging optical system of the zoom lens and receives the image with an image sensor such as a CCD or a silver salt film to perform imaging. it can. As a specific product, for example, the photographing apparatus can be widely applied as a digital terminal device such as a digital camera, a personal computer, a mobile phone, or a PDA (Personal Digital Assistant) incorporating a camera. Hereinafter, one of the embodiments will be exemplified.

13 to 15 are conceptual diagrams of the configuration of the digital camera according to the present invention in which the zoom lens as described above is incorporated in the photographing optical system 41. FIG. 13 is a front perspective view showing the external appearance of the digital camera 40, FIG. 14 is a rear front view thereof, and FIG. 15 is a schematic cross-sectional view showing the configuration of the digital camera 40. However, FIGS. 13 and 15 show a state in which the photographing optical system 41 is not retracted. In this example, the digital camera 40 includes a photographing optical system 41 located on the photographing optical path 42, a finder optical system 43 located on the finder optical path 44, a shutter button 45, a flash 46, a liquid crystal display monitor 47, a focal length. When the photographic optical system 41 is retracted, the photographic optical system 41, the finder optical system 43, and the flash 46 are covered with the cover 60, including the change button 61, the setting change switch 62, and the like. Then, when the cover 60 is opened and the camera 40 is set to the photographing state, the photographing optical system 41 is brought into the non-collapsed state of FIG. 15, and when the shutter button 45 disposed on the upper part of the camera 40 is pressed, photographing is performed in conjunction therewith. Photographing is performed through the optical system 41, for example, the zoom lens of the first embodiment. An object image formed by the photographic optical system 41 is formed on the imaging surface (photoelectric conversion surface) of the CCD 49 via a low-pass filter F and a cover glass C that are provided with a wavelength band limiting 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 unit 52 may be provided separately from the processing unit 51, or may be configured to perform recording and writing electronically using a floppy (registered trademark) disk, a memory card, an 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 finder objective optical system 53 includes a plurality of lens groups (three groups in the figure) and an erecting prism system 55 including erecting prisms 55a, 55b, and 55c, and is linked to the zoom lens of the photographing optical system 41. The object image formed by the finder objective optical system 53 is formed on a field frame 57 of an erecting prism system 55 that is an image erecting member. Behind the erecting prism system 55, an eyepiece optical system 59 for guiding the erect image to the observer eyeball E is disposed. A cover member 50 is disposed on the exit side of the eyepiece optical system 59.

  FIG. 16 shows a schematic block diagram of the internal configuration of the main part of the digital camera 40. Note that the operation unit represented by the shutter button 45 is denoted by reference numeral 500, the processing means is a CPU 51, the imaging element is a CCD 49, and the recording means is a memory card 521 and an external storage device (optical disk). , HDD, etc.) 522. When the CPU 51 determines that the shutter button 45 of the operation unit 500 has been pressed, the optimal shutter control value and aperture control are calculated by exposure control, and the shutter and aperture control are performed based on these control values after the calculation. Other control operations are as described above.

  The digital camera 40 configured in this manner has improved optical performance of the photographing optical system 41 and can be made compact in size, so that the entire camera can be upgraded and downsized.

FIG. 2 is a lens cross-sectional view at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity according to the first exemplary embodiment of the zoom lens of the present invention. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of Embodiment 2 of the zoom lens according to the present invention. FIG. 5 is a lens cross-sectional view similar to FIG. 1 of Embodiment 3 of the zoom lens according to the present invention. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of Embodiment 4 of the zoom lens according to the present invention. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of Embodiment 5 of the zoom lens according to the present invention. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of Embodiment 6 of the zoom lens according to the present invention. FIG. 6 is an aberration diagram at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity according to Example 1. FIG. 10 is an aberration diagram similar to FIG. 7 of Example 2. FIG. 10 is an aberration diagram similar to FIG. 7 of Example 3. FIG. 10 is an aberration diagram similar to FIG. 7 of Example 4. FIG. 10 is an aberration diagram similar to FIG. 7 of Example 5. FIG. 10 is an aberration diagram similar to FIG. 7 of Example 6. It is a front perspective view which shows the external appearance of the digital camera by this invention. FIG. 14 is a rear perspective view of the digital camera of FIG. 13. It is sectional drawing of the digital camera of FIG. It is a schematic block diagram of the internal structure of the principal part of the digital camera of FIG.

Explanation of symbols

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group G4 ... 2nd lens group G5 ... 3rd lens group S ... Aperture stop F ... Low pass filter C ... Cover glass I ... Image plane E ... Observer Eyeball 40 ... Digital camera 41 ... Shooting optical system 42 ... Shooting optical path 43 ... Viewfinder optical system 44 ... Viewfinder optical path 45 ... Shutter button 46 ... Flash 47 ... Liquid crystal display monitor 49 ... CCD
DESCRIPTION OF SYMBOLS 50 ... Cover member 51 ... Processing means 52 ... Recording means 53 ... Viewfinder objective optical system 55 ... Erect prism 57 ... Field frame 59 ... Eyepiece optical system 60 ... Cover 61 ... Focal length change button 62 ... Setting change switch 500 ... Operation Unit 521 ... Memory card 522 ... External storage device (optical disk, HDD)

Claims (13)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a positive refractive power. and a fifth lens group performs zooming by varying the interval between the lens units, the first lens unit moves so that the object side at the telephoto end than at the wide angle end, the fifth lens group Moving from the wide-angle end to the image side at the telephoto end, the axial distance between the third lens group and the fourth lens group increases from the wide-angle end to the intermediate zoom position, and from the intermediate zoom position to the telephoto end. The zoom lens is characterized by decreasing over the period. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
4.00 <L _w / f _w <9.00 (1)
Where L _w is the total length at the wide-angle end,
f _w : the focal length of the entire system at the wide-angle end,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1.00 <L _t / f _t <1.80 (2)
Where L _t is the total length at the telephoto end,
f _t : Total focal length at the telephoto end,
It is. 4. The zoom lens according to claim 1, wherein the first lens group includes one positive lens. 5. The zoom lens according to claim 4, wherein the positive lens of the first lens group satisfies the following conditional expression.
75.0 <ν _d1p <105.0 (3)
Where ν _{d1p is} the Abbe number of the positive lens in the first lens group,
It is. The zoom lens according to claim 4 or 5, wherein the positive lens of the first lens group satisfies the following conditional expression.
−1.50 <SF _1p <−0.20 (4)
However, as defined in _{SF 1p = (R 1pf + R} 1pr) / (R 1pf -R 1pr), R 1pf, the object side surface of the positive lens of each of R _1pr the first lens group, in axial radius of curvature of the image side surface is there. The zoom lens according to any one of claims 1 to 6, wherein the second lens group includes a negative lens L21, a negative lens L22, and a positive lens L23 in order from the object side. The negative lens L21 has a concave surface facing the image side, the negative lens L22 has a concave surface facing the object side, and the negative lens L22 and the positive lens L23 are cemented. The described zoom lens. A zoom lens according to any one of claims 1 to 8 and an electronic image sensor, wherein image data obtained by imaging an image formed through the zoom lens with the electronic image sensor is processed. In an electronic imaging device capable of outputting as image data with a changed shape,
An electronic imaging apparatus, wherein the imaging optical system satisfies the following conditions when focusing on an object point at approximately infinity.
_{0.850 <y 07 / (f w} · tanω 07w) <0.970 ··· (17)
However, if the distance (maximum image height) from the center to the farthest point in the effective imaging plane (in the plane where imaging is possible) of the electronic imaging device is y ₁₀ , y ₀₇ = 0.7 y ₁₀ and ω _07w are at the wide-angle end. Is an angle with respect to the optical axis in the object direction corresponding to the image point connected to the position of _y07 from the center on the effective imaging surface of the electronic imaging device. 9. An electronic imaging apparatus comprising: the zoom lens according to claim 1; and an imaging element disposed at a position for receiving an object image formed by the zoom lens. The zoom lens according to any one of claims 1 to 8, an image sensor disposed at a position for receiving an object image formed by the zoom lens, and an electronic signal photoelectrically converted by the image sensor A CPU; an input unit for inputting an information signal that an operator wants to input to the CPU; display processing means for displaying an output from the CPU on a display device; and a recording medium for recording the output from the CPU. And the CPU is configured to display an object image received by the imaging device by the zoom lens on the display device. The information processing apparatus according to claim 11, wherein the information processing apparatus is a mobile terminal device. The zoom lens according to any one of claims 1 to 8, an image sensor disposed at a position for receiving an object image formed by the zoom lens, and an electronic signal photoelectrically converted by the image sensor A CPU and a display element that displays the object image received by the image sensor so as to be observable, and a recording medium for recording image information of the object image received by the image sensor is built in or removed. Configured such that the CPU displays on the display element the object image received by the image sensor, and recording processing means for recording the object image received by the image sensor on the recording medium. An electronic camera device comprising:

Images