JP2006023438A - Variable power optical system and electronic apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable power optical system whose miniaturization is effectively made compatible with the reduction in cost, and electronic apparatus using the same. <P>SOLUTION: The variable power optical system is constituted of a 1st lens group G1 having negative refractive power, a 2nd lens group G2 having positive refractive power, a 3rd lens group G3 having negative refractive power and a 4th lens group G4 having positive refractive power in order from an object side. In the variable power optical system, the 2nd lens group G2 comprises one positive lens, and the 2nd and the 3rd lens groups G2 and G3 satisfy a conditional expression concerning the ratio of their synthetic front side principal point position at a wide angle end to the total sum of the thickness of lenses. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable magnification optical system and an electronic apparatus using the same, and more particularly to a compact variable magnification optical system and an electronic apparatus using such a variable magnification optical system. Examples of the electronic apparatus include a digital camera, a video camera, a digital video unit, a personal computer, a mobile computer, a mobile phone, and an information portable terminal.

In recent years, portable information terminals and mobile phones called PDAs have become explosive. Many of these devices have built-in compact digital cameras and digital video units. Here, in these digital cameras and digital video units, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor is used as an imaging device. In such a digital camera or the like, an image sensor having a relatively small effective area of the light receiving surface is used. Therefore, when downsizing such a digital camera or the like, it is necessary to achieve both miniaturization and cost reduction while maintaining high performance of the optical system. Conventionally, as one of the downsized and low-cost optical systems, there is a negative / positive / negative positive variable magnification optical system disclosed in Patent Document 1 or the like.
Japanese Patent Laid-Open No. 10-48524

  However, since the lens described in Patent Document 1 uses two lenses in the second group, the thickness of the second group becomes large and the entire length of the lens becomes long.

  The present invention has been made in view of such a situation in the prior art, and an object thereof is a variable magnification optical system capable of effectively achieving both cost reduction and downsizing, and an electronic apparatus using the same. Is to provide.

The first variable magnification optical system of the present invention that achieves the above object includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a negative refractive power. A variable magnification optical system including a third lens group having a fourth refractive index and a fourth lens group having a positive refractive power,
The second lens group is composed of one positive lens,
The variable power optical system characterized in that the second lens group and the third lens group satisfy the following conditional expression.

−100 <HF ₂₃ / SD ₂₃ <−0.3 (1)
However, HF ₂₃ : the front principal point position of the composition at the wide angle end of the second lens group and the third lens group (value measured from the top of the object side surface of the second lens group),
SD ₂₃ : Sum of lens thicknesses included in the second lens group and the third lens group,
It is.

  Hereinafter, the reason and operation of the first variable magnification optical system will be described.

  As a variable magnification optical system, there is one having a negative, positive, and positive power arrangement. This variable magnification optical system can realize an optical system having a fixed overall length with a small number of lenses and a short overall length. Therefore, a variable magnification optical system having negative, positive and negative power arrangements is preferable because a compact and low-cost optical system can be realized.

  In that case, it is preferable to realize the second lens group with one positive lens. By doing so, the optical system can be configured with a smaller number of sheets, which is preferable because the size can be reduced and the cost can be reduced. Also, the second lens group can be reduced in weight when moving or focusing by moving the second lens group. Therefore, a moving mechanism such as an actuator for moving the lens group can be reduced in size, and the entire unit can be reduced in size, which is preferable.

  The second lens group and the third lens group preferably satisfy the conditional expression (1). When the conditional expression (1) is satisfied, the front principal point position of the synthesis of the second lens group and the third lens group is closer to the first lens side, and the principal point of the first lens group, the second lens group, and the third lens group. The distance from the composite principal point can be shortened, leading to a reduction in the overall lens length. When the upper limit of −0.3 in conditional expression (1) is exceeded, the position of the principal point of the combination of the second lens group and the third lens group moves to the image side, and the distance between the principal points of the first lens group increases. End up. Then, the total length becomes long, which is not preferable. Exceeding the lower limit of −100 is not preferable because the power of the second lens group and the third lens group becomes too strong and the decentration sensitivity becomes high.

  Furthermore, it is preferable that the following conditional expression (1-2) is satisfied. Satisfying this condition is more preferable because the total lens length can be shortened.

−50 <HF ₂₃ / SD ₂₃ <−0.35 (1-2)
Furthermore, it is preferable that the following conditional expression (1-3) is satisfied. Satisfying this condition is more preferable because the total lens length can be further shortened.

−30 <HF ₂₃ / SD ₂₃ <−0.37 (1-3)
According to a second variable power optical system of the present invention, in the first variable power optical system, at least one negative lens included in the first lens group has an aspherical surface on the object side. To do.

  Hereinafter, the reason and operation of the second variable magnification optical system will be described.

  At the wide-angle end, the light ray height at the first lens group is high. Therefore, it is preferable to provide an aspheric surface on the object side of the negative lens. By doing so, off-axis aberrations such as coma can be corrected well.

  At the telephoto end, the light beam diameter in the first lens group is large. Therefore, it is preferable to provide an aspheric surface on the object side of the negative lens. By doing so, spherical aberration and the like can be corrected satisfactorily.

  According to a third variable magnification optical system of the present invention, in the first and second variable magnification optical systems, at least one negative lens included in the first lens group has an aspherical surface on the image side. It is characterized by.

  Hereinafter, the reason and operation of the third variable magnification optical system will be described.

  At the wide-angle end, the light ray height at the first lens group is high. Therefore, it is preferable to provide an aspheric surface on the image side of the negative lens. By doing so, off-axis aberrations such as astigmatism can be favorably corrected.

  At the telephoto end, the light beam diameter in the first lens group is large. Therefore, it is preferable to provide an aspheric surface on the image side of the negative lens. By doing so, spherical aberration and the like can be corrected satisfactorily.

  According to a fourth variable magnification optical system of the present invention, in the first to third variable magnification optical systems, at least one negative lens included in the first lens group is a lens made of a resin material. It is characterized by.

  Hereinafter, the reason and action of the fourth variable magnification optical system having the above configuration will be described. Resin material lenses can be manufactured at a lower cost than glass. Accordingly, at least one negative lens included in the first lens group is preferably made of a resin material.

  The fifth variable power optical system of the present invention is characterized in that, in the first to fourth variable power optical systems, the first lens group satisfies the following conditional expression.

−10 <SF _G1 <1 (2)
Where SF _G1 is the shaping factor of the first lens group,
SF _G1 = (r _G11 + r _G12 ) / (r _G11 −r _G12 )
r _G11 : radius of curvature of the most object side surface of the first lens group,
r _G12 : radius of curvature of the most image-side surface of the first lens group,
It is.

  Hereinafter, the reason and action of the fifth variable magnification optical system having the above configuration will be described.

  In the first lens group, the lens diameter is larger than that of the second lens group or the third lens group. At this time, by providing power to the first lens group, the entrance pupil position can be positioned closer to the object side. As a result, not only the effective lens diameter can be reduced, but also the overall lens length can be shortened. And it is preferable to satisfy the conditional expression (2). By satisfying this condition, the effective lens diameter can be reduced while maintaining good performance. When the upper limit of 1 in the conditional expression (2) is exceeded, the positive power of the object side surface becomes positive, and the entrance pupil position is located more on the image side. As a result, the effective lens diameter increases. Therefore, it is not preferable to exceed the upper limit value. If the lower limit value of −10 in conditional expression (2) is not reached, the negative power on the object side becomes too strong. In this case, coma aberration generated at the wide-angle end, astigmatism generated at the telephoto end, and the like become large. Therefore, it is not preferable for aberration correction to be below the lower limit.

  Furthermore, it is preferable that the following conditional expression (2-2) is satisfied. By satisfying this condition, the effective lens diameter can be reduced while maintaining good performance.

-1 <SF _G1 <1 (2-2)
Furthermore, it is preferable that the following conditional expression (2-3) is satisfied. By satisfying this condition, the effective lens diameter can be further reduced while maintaining better performance.

-0.5 <SF _G1 <1 (2-3)
According to a sixth variable magnification optical system of the present invention, in the first to fifth variable magnification optical systems, at least one negative lens included in the first lens group is made of a material that satisfies the following conditional expression. It is characterized by that.

40 <ν _d1 <100 (3)
Where ν _{d1 is} the Abbe number of the negative lens in the first lens group,
It is.

  Hereinafter, the reason and operation of the sixth variable magnification optical system having the above configuration will be described.

  Since the first lens group has a negative power, large lateral chromatic aberration occurs particularly at the wide-angle end. Moreover, if the first lens group is composed of one negative lens, it is advantageous in terms of compactness, but it is not possible to suppress the amount of lateral chromatic aberration generated by arranging a positive lens in the first lens group. Therefore, it is preferable that the negative lens of the first lens group satisfies the conditional expression (3). By satisfying this condition, the amount of chromatic aberration of magnification can be reduced. If the upper limit of 100 in conditional expression (3) is exceeded, no material is present. The lateral chromatic aberration generated in the first lens group that is lower than the lower limit of 40 is too large. Therefore, a large number of lenses are required to suppress lateral chromatic aberration in the entire system.

  Furthermore, it is preferable that the following conditional expression (3-2) is satisfied. By satisfying this condition, the amount of chromatic aberration of magnification can be reduced.

50 <ν _d1 <100 (3-2)
Furthermore, it is preferable that the following conditional expression (3-3) is satisfied. By satisfying this condition, the amount of chromatic aberration of magnification can be reduced.

55 <ν _d1 <100 (3-3)
A seventh variable magnification optical system according to the present invention is characterized in that, in the first to sixth variable magnification optical systems, at least one negative lens included in the first lens group satisfies the following conditional expression: To do.

0.5 <| f ₁ | / f _w <5 (4)
However, f _1: focal length of the negative lens in the first lens group,
f _w : the converted focal length of the entire system at the wide-angle end,
f _w = (Y _h × 0.6) / tanω
Y _h : maximum image height,
ω: half angle of view of light incident on 60% of maximum image height,
It is.

  Hereinafter, the reason and operation of the seventh variable magnification optical system will be described.

  In the first lens group, the lens diameter is larger than that of the second lens group or the third lens group. Thus, by providing power to the first lens group, the entrance pupil position can be positioned closer to the object side. As a result, not only the effective lens diameter can be reduced, but also the overall lens length can be shortened. At this time, by satisfying the conditional expression (4), it is possible to reduce the effective lens diameter and the total lens length while maintaining good performance. If the upper limit of 5 in the conditional expression (4) is exceeded, the negative power becomes too strong, and coma aberration generated at the wide-angle end, astigmatism generated at the telephoto end, and the like increase. Therefore, exceeding the upper limit is not preferable in terms of aberration correction. If the lower limit of 0.5 in conditional expression (4) is not reached, the negative power becomes weak, and the effective lens diameter and the total lens length cannot be made sufficiently small. Therefore, it is not preferable to fall below the lower limit.

  Furthermore, it is preferable that the following conditional expression (4-2) is satisfied. By satisfying this condition, the effective lens diameter and the total lens length can be reduced while maintaining good performance.

1 <| f ₁ | / f _w <3 (4-2)
Furthermore, it is preferable that the following conditional expression (4-3) is satisfied. By satisfying this condition, the effective lens diameter and the total lens length can be further reduced while maintaining better performance.

1.4 <| f ₁ | / f _w <2.5 (4-3)
An eighth variable magnification optical system according to the present invention is characterized in that, in the first to seventh variable magnification optical systems, the first lens group has at least one positive lens.

  Hereinafter, the reason and action of the above configuration in the eighth variable magnification optical system will be described.

  In the first lens group, the lens diameter is larger than that of the second lens group or the third lens group. In this case, by increasing the negative refractive power of the first lens group, the entrance pupil position can be located closer to the object side. As a result, not only the effective lens diameter can be reduced, but also the overall lens length can be shortened. However, when the power of the negative lens in the first lens group is increased, the lateral chromatic aberration is increased. This is not preferable in terms of aberration correction. Therefore, it is preferable to arrange a positive lens in the first lens group. By doing so, the amount of lateral chromatic aberration of the first lens group can be reduced.

  The ninth variable magnification optical system according to the present invention is characterized in that, in the eighth variable magnification optical system, the positive lens is disposed closest to the image side.

  Hereinafter, the reason and action of the ninth variable power optical system will be described. By making the most image side of the first lens group the positive lens, it is possible to suppress variations in various aberrations such as spherical aberration, coma aberration, and chromatic aberration of magnification due to zooming.

  A tenth variable magnification optical system according to the present invention is characterized in that in the first to ninth variable magnification optical systems, the positive lens of the second lens group is made of a material that satisfies the following conditional expression. To do.

−30 × 10 ⁻⁶ <dn ₂ / dT <50 × 10 ⁻⁶ (5)
Where dn ₂ / dT: temperature coefficient of refractive index at the d-line of the positive lens in the second lens group [° C. ⁻¹ ],
It is.

  Hereinafter, the reason and operation of the tenth zoom optical system having the above configuration will be described.

When the positive lens of the second lens group has a large power, the movement amount of the second lens group becomes small. As a result, a compact optical system can be realized. However, the influence of a change in refractive index when the temperature changes increases, leading to performance degradation. Here, if the second lens group is composed of a plurality of lenses so that the change in refractive index can be canceled, the entire length of the second lens group becomes long, and the optical system cannot be downsized. Therefore, it is preferable that the optical system satisfies the conditional expression (5). When this condition is satisfied, the amount of change in the refractive index when the temperature changes is small, and downsizing can be realized while effectively preventing performance degradation. If the upper limit of 50 × 10 ^{−6 in} conditional expression (5) is exceeded or less than the lower limit of −30 × 10 ⁻⁶ , the refractive index changes greatly when the temperature changes, and good performance is achieved. It can no longer be obtained.

  Furthermore, it is preferable that the following conditional expression (5-2) is satisfied. By satisfying this condition, the amount of change in the refractive index when the temperature changes can be further reduced.

−20 × 10 ⁻⁶ <dn ₂ / dT <30 × 10 ⁻⁶ (5-2)
Furthermore, it is preferable that the following conditional expression (5-3) is satisfied. By satisfying this condition, the amount of change in refractive index when the temperature changes can be further reduced.

−10 × 10 ⁻⁶ <dn ₂ / dT <10 × 10 ⁻⁶ (5-3)
An eleventh variable magnification optical system according to the present invention is characterized in that, in the first to tenth variable magnification optical systems, the positive lens of the second lens group has an aspheric surface on the object side.

  Hereinafter, the reason and action of the eleventh variable magnification optical system adopting the above configuration will be described. The beam diameter in the second lens group is large. Therefore, it is preferable to provide an aspheric surface on the object side of the positive lens. By doing so, it is possible to satisfactorily correct spherical aberration and the like particularly at the wide angle end.

  According to a twelfth variable magnification optical system of the present invention, in the first to eleventh variable magnification optical systems, the positive lens of the second lens group has an aspheric surface on the image side.

  Hereinafter, the reason and action of the twelfth variable magnification optical system having the above configuration will be described.

  The beam diameter in the second lens group is large. Therefore, it is preferable to provide an aspherical surface on the image side of the positive lens. By doing so, it is possible to satisfactorily correct spherical aberration and the like particularly at the wide angle end.

  Further, since the positive lens of the second lens group has a large power, the movement amount of the second lens group becomes small. As a result, a compact optical system can be realized. However, if the positive lens in the second lens group has a large power, astigmatism, coma and the like are greatly generated. Therefore, it is preferable to provide an aspherical surface on the image side of the positive lens. By doing so, it is possible to satisfactorily correct coma, astigmatism and the like particularly at the wide angle end.

  A thirteenth variable magnification optical system according to the present invention is characterized in that, in the first to twelfth variable magnification optical systems, the second lens group satisfies the following conditional expression.

−5 <SF ₂ <1 (6)
Where SF ₂ is the shaping factor of the positive lens in the second lens group,
SF ₂ = (r ₂₁ + r ₂₂ ) / (r ₂₁ −r ₂₂ )
r ₂₁ : radius of curvature of the object side surface of the positive lens in the second lens group,
r ₂₂ : radius of curvature of the image side surface of the positive lens in the second lens group,
It is.

  Hereinafter, the reason and operation of the thirteenth variable magnification optical system will be described.

  When the positive lens in the second lens group satisfies the conditional expression (6), the positive refractive power of the image side surface can be reduced, and the following effects (1) and (2) are obtained. (1) The principal point position moves to the first lens group side, the distance between the principal points of the first lens group and the second lens group can be shortened, leading to a shortening of the entire lens length. (2) Since the magnification of the second lens group can be increased, the amount of movement of the second lens group accompanying zooming can be reduced, leading to a reduction in the overall length.

  When the upper limit of 1 in conditional expression (6) is exceeded, the positive refractive power of the image side surface increases. In this case, since the magnification of the second lens group becomes small, the zoom ratio becomes small. Alternatively, in order to obtain the same zoom ratio, the amount of movement of the second lens group accompanying zooming becomes large. Below the lower limit of −5, both astigmatism occurring on the object side surface and coma occurring on the image side surface become too large. Therefore, many lenses are required for correction.

  Furthermore, it is preferable that the following conditional expression (6-2) is satisfied. If this condition is satisfied, the optical system can be made compact.

-1 <SF ₂ <0.5 (6-2)
Furthermore, it is preferable that the following conditional expression (6-3) is satisfied. By satisfying this condition, the optical system can be made more compact.

−0.5 <SF ₂ <0 (6-3)
A fourteenth variable magnification optical system according to the present invention is characterized in that, in the first to thirteenth variable magnification optical systems, the positive lens of the second lens group is made of a material that satisfies the following conditional expression. To do.

35 <ν _d2 <100 (7)
Where ν _{d2 is} the Abbe number of the positive lens in the second lens group,
It is.

  The reason and action of the above-described configuration in the fourteenth variable magnification optical system will be described below.

  Since the positive lens of the second lens group has a large power, the movement amount of the second lens group becomes small. As a result, a compact optical system can be realized. However, if the positive lens in the second lens group has a large power, a large axial chromatic aberration will occur accordingly. Therefore, it is preferable that the positive lens of the second lens group satisfies the conditional expression (7). When this condition is satisfied, the amount of axial chromatic aberration generated can be reduced. If the upper limit of 100 in conditional expression (7) is exceeded, no material is present. If the lower limit of 35 is not reached, the longitudinal chromatic aberration generated in the second lens group becomes too large. Therefore, a large number of lenses are required to suppress axial chromatic aberration in the entire system. Therefore, it is not preferable to fall below the lower limit.

  Furthermore, it is preferable that the following conditional expression (7-2) is satisfied. By satisfying this condition, the amount of axial chromatic aberration generated can be reduced.

40 <ν _d2 <100 (7-2)
Furthermore, it is preferable that the following conditional expression (7-3) is satisfied. By satisfying this condition, the amount of axial chromatic aberration generated can be further reduced.

45 <ν _d2 <100 (7-3)
A fifteenth variable magnification optical system according to the present invention is characterized in that, in the first to fourteenth variable magnification optical systems, the positive lens of the second lens group satisfies the following conditional expression.

0.3 <| f ₂ | / f _w <1.3 (8)
Where f _{2 is} the focal length of the positive lens in the second lens group,
f _w : the converted focal length of the entire system at the wide-angle end,
f _w = (Y _h × 0.6) / tanω
Y _h : maximum image height,
ω: half angle of view of light incident on 60% of maximum image height,
It is.

  Hereinafter, the reason and operation of the fifteenth variable magnification optical system will be described.

  Since the positive lens of the second lens group has a large power, the movement amount of the second lens group becomes small. As a result, a compact optical system can be realized. However, when the positive lens in the second lens group has a large power, axial chromatic aberration, coma aberration, astigmatism, etc. are greatly generated. Therefore, it is preferable to satisfy the conditional expression (8). Satisfying this condition is preferable because a compact optical system can be realized while maintaining good performance. If the upper limit of 1.3 in conditional expression (8) is exceeded, the positive power becomes too strong. In this case, axial chromatic aberration, coma and astigmatism at the wide-angle end, etc. become large. Therefore, exceeding the upper limit is not preferable in terms of aberration correction. If the lower limit of 0.3 in conditional expression (8) is not reached, the positive power will be weak. In this case, since the movement amount of the second lens group becomes large, the total lens length cannot be made sufficiently small. Therefore, it is not preferable to fall below the lower limit.

  Furthermore, it is preferable that the following conditional expression (8-2) is satisfied. By satisfying this condition, the effective lens diameter and the total lens length can be reduced while maintaining good performance.

0.4 <| f ₂ | / f _w <1 (8-2)
Furthermore, it is preferable that the following conditional expression (8-3) is satisfied. By satisfying this condition, the effective lens diameter and the total lens length can be further reduced while maintaining good performance.

0.5 <| f ₂ | / f _w <0.9 (8-3)
According to a sixteenth variable magnification optical system of the present invention, in the first to fifteenth variable magnification optical systems, the positive lens of the second lens group is another lens included in the first lens group and the third lens group. It is characterized by being made of a material having a higher refractive index than any of the above.

  The reason and action of the above configuration in the sixteenth variable magnification optical system will be described below.

  Since the positive lens of the second lens group has a large power, the movement amount of the second lens group is reduced, and a compact optical system can be realized. However, the Petzval sum increases and the field curvature increases. Therefore, it is preferable that the refractive index of the positive lens of the second lens group be higher than any of the other lenses included in the first lens group and the third lens group. In this way, the Petzval sum is reduced, and the curvature of field can be effectively suppressed while being compact.

  According to a seventeenth variable magnification optical system of the present invention, in the first to sixteenth variable magnification optical systems, at least one negative lens of the third lens group is a lens made of a resin material. It is what.

  Hereinafter, the reason and action of the above-described configuration in the seventeenth variable magnification optical system will be described. A lens made of a resin material can be manufactured at a lower cost than glass. Therefore, it is preferable that at least the negative lens of the third lens group is made of resin.

  According to an eighteenth variable magnification optical system of the present invention, in the first to seventeenth variable magnification optical systems, at least one negative lens of the third lens group satisfies the following conditional expression: It is.

−1 <SF ₃ <10 (9)
Where SF ₃ is the shaping factor of the negative lens of the third lens group,
SF ₂ = (r ₃₁ + r ₃₂ ) / (r ₃₁ −r ₃₂ )
r ₃₁ : radius of curvature of the object side surface of the negative lens of the third lens group,
r ₃₂ : radius of curvature of the image side surface of the negative lens of the third lens group,
It is.

  The reason and action of the above configuration in the eighteenth variable magnification optical system will be described below.

  By satisfying conditional expression (9), the principal point position of the negative lens of the third lens group becomes closer to the object side. For this reason, the distance between the principal points of the second lens group and the third lens group can be shortened, leading to a reduction in the total lens length. If the upper limit of 10 in the conditional expression (9) is exceeded, fluctuations in various aberrations such as astigmatism occurring on the image side surface become large. Therefore, exceeding the upper limit is not preferable in terms of aberration correction. Below the lower limit of -1, the principal point position of the negative lens of the third lens group is located on the image side. For this reason, the main point interval between the second lens group and the third lens group becomes long, and the total lens length also increases. Therefore, it is not preferable to fall below the lower limit.

  Furthermore, it is preferable that the following conditional expression (9-2) is satisfied. If this condition is satisfied, the optical system can be made compact.

−0.5 <SF ₃ <5 (9-2)
Furthermore, it is preferable that the following conditional expression (9-3) is satisfied. By satisfying this condition, the optical system can be made more compact.

0 <SF ₃ <2 (9-3)
According to a nineteenth variable magnification optical system of the present invention, in the first to eighteenth variable magnification optical systems, at least one negative lens of the third lens group is made of a material that satisfies the following conditional expression. It is characterized by this.

0 <ν _d3 <45 (10)
Where ν _{d3 is} the Abbe number of the negative lens in the third lens group,
It is.

  The reason and action of the above-described configuration in the nineteenth variable magnification optical system will be described below.

  For compactness, it is better that the number of lenses in the first lens group is small. In particular, the first lens group may be composed of one negative lens. However, if the first lens group is composed of one negative lens, the lateral chromatic aberration is greatly generated. In addition, axial chromatic aberration occurs in the second lens group. Therefore, by satisfying conditional expression (10), it is possible to satisfactorily correct lateral chromatic aberration even when the first lens group is composed of one negative lens. In addition, it is possible to satisfactorily correct axial chromatic aberration generated in the second lens group. If the upper limit of 45 in the conditional expression (10) is exceeded, the lateral chromatic aberration generated in the first lens group and the axial chromatic aberration generated in the second lens group cannot be corrected well. Therefore, exceeding the upper limit is not preferable in terms of aberration correction. In particular, if the axial chromatic aberration generated in the second lens group cannot be corrected, the fluctuation of the axial chromatic aberration due to zooming becomes large. If so, the image quality at the center of the image is greatly degraded. Therefore, it is not preferable to exceed the upper limit value. Below the lower limit of 0, no material is present.

  Furthermore, it is preferable that the following conditional expression (10-2) is satisfied. By satisfying this condition, chromatic aberration generated in the first lens group and the second lens group can be corrected more favorably.

0 <ν _d3 <40 (10-2)
Furthermore, it is preferable that the following conditional expression (10-3) is satisfied. By satisfying this condition, the chromatic aberration generated in the first lens group and the second lens group can be corrected more satisfactorily.

0 <ν _d3 <35 (10-3)
According to a twentieth variable magnification optical system of the present invention, in the first to nineteenth variable magnification optical systems, at least one positive lens in the fourth lens group is made of a resin material. Is.

  Hereinafter, the reason and action of the twentieth variable magnification optical system having the above configuration will be described. A lens made of a resin material can be manufactured at a lower cost than glass. Therefore, it is preferable that at least one positive lens of the fourth lens group is made of a resin material.

  According to a twenty-first variable power optical system of the present invention, in the first to twentieth variable power optical system, at least one positive lens in the fourth lens group satisfies the following conditional expression: It is.

-1 <SF ₄ <10 (11)
Where SF ₄ is the shaping factor of the positive lens in the fourth lens group,
SF ₄ = (r ₄₁ + r ₄₂ ) / (r ₄₁ −r ₄₂ )
r _41: the curvature of the object side surface of the positive lens in the fourth lens group,
r ₄₂ : radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.

  Hereinafter, the reason and effect of the above-described configuration in the twenty-first variable magnification optical system will be described.

  In order to reduce the amount of aberration generated in the third lens group, it is preferable that the ray height in the third lens group is small. At this time, it is preferable that the fourth lens group satisfies the conditional expression (11). When this condition is satisfied, the positive refractive power of the object side surface becomes small. As a result, the amount of coma and astigmatism generated on the object side surface can be reduced. When the upper limit of 10 to conditional expression (11) is exceeded, the negative refractive power of the object side surface becomes too large. In this case, coma aberration, astigmatism and the like are overcorrected, and these aberrations are greatly generated on the opposite side to the case where the conditional expression (11) is satisfied. In addition, the eccentric sensitivity is increased, which is not preferable. Below the lower limit of −1, the positive refractive power of the object side surface increases. In this case, the amount of various aberrations such as coma and astigmatism increases. In this case, a larger number of lenses is required for correction. Therefore, it is not preferable to fall below the lower limit.

  Furthermore, it is preferable that the following conditional expression (11-2) is satisfied. By satisfying this condition, the amount of various aberrations can be reduced.

0 <SF ₄ <7 (11-2)
Furthermore, it is preferable that the following conditional expression (11-3) is satisfied. By satisfying this condition, the amount of various aberrations can be further reduced.

0.5 <SF ₄ <4 (11-3)
According to a twenty-second variable power optical system of the present invention, in the first to twenty-first variable power optical system, at least one positive lens in the fourth lens group is made of a material that satisfies the following conditional expression: It is characterized by.

40 <ν _d4 <100 (12)
Where ν _{d4 is} the Abbe number of the positive lens in the fourth lens group,
It is.

  Hereinafter, the reason and action of the above configuration in the twenty-second variable magnification optical system will be described.

  For compactness, it is better that the number of lenses in the first lens group is small. In particular, the first lens group may be composed of one negative lens. However, if the first lens group is composed of a single negative lens, the lateral chromatic aberration is particularly large at the wide-angle end. Here, if this lateral chromatic aberration is corrected with the negative refractive power of the third lens group, the correction will be overcorrected at the telephoto end. Therefore, it is preferable to satisfy the conditional expression (12). By satisfying this condition, the occurrence of lateral chromatic aberration due to overcorrection at the telephoto end can be satisfactorily suppressed. If the upper limit of 100 in conditional expression (12) is exceeded, no material is present. When the lower limit of 40 is not reached, it is impossible to suppress lateral chromatic aberration that occurs at the telephoto end. In this case, a larger number of lenses is required for correction. Therefore, it is not preferable to fall below the lower limit.

  Furthermore, it is preferable that the following conditional expression (12-2) is satisfied. By satisfying this condition, it is possible to more effectively suppress the occurrence of lateral chromatic aberration.

45 <ν _d4 <100 (12-2)
Furthermore, it is preferable that the following conditional expression (12-3) is satisfied. By satisfying this condition, the occurrence of lateral chromatic aberration can be suppressed more satisfactorily.

50 <ν _d4 <100 (12-3)
According to a twenty-third variable power optical system of the present invention, in the first to twenty-second variable power optical systems, the position of the first lens group in the optical axis direction is fixed at the time of zooming. is there.

  The reason and action of the above-described configuration in the twenty-third variable magnification optical system will be described below. If the position of the first lens group in the optical axis direction is fixed at the time of zooming, the number of moving means such as actuators can be reduced. As a result, it is possible to further reduce the overall size and cost including the moving means and the like.

  According to a twenty-fourth variable power optical system of the present invention, in the first to twenty-third variable power optical systems, an interval between the second lens group and the third lens group is constant during zooming. Is.

  Hereinafter, the reason and action of the above configuration in the twenty-fourth variable magnification optical system will be described.

  When the second lens group and the third lens group have large power, the movement amount of the second lens group and the third lens group becomes small. Therefore, this is preferable. However, the eccentricity sensitivity is also increased, and the performance is likely to deteriorate. Therefore, it is preferable to keep the distance between the second lens group and the third lens group constant during zooming. In this way, since the second lens group and the third lens group are moved together, the occurrence of relative decentering between the second lens group and the third lens group can be suppressed. As a result, performance degradation can be effectively suppressed.

  The 25th variable magnification optical system of the present invention is characterized in that, in the 1st to 24th variable magnification optical systems, the following conditional expressions are satisfied.

−35 <DT _min <20 (13)
However, DT _min : Distortion amount [%],
It is.

  Hereinafter, the reason and action of the above configuration in the 25th variable magnification optical system will be described.

When the distortion is electrically corrected to widen the angle of view, it is preferable to satisfy the conditional expression (13). By satisfying this condition, it is possible to realize a wide angle of view with good image quality when distortion is electrically corrected. If it exceeds 20% of the upper limit of conditional expression (13), positive distortion will occur at the wide-angle end. In this case, a wide angle of view cannot be realized even if the distortion aberration is electrically corrected. Below -30% of the lower limit, the enlargement magnification at the outermost periphery of the image increases. Therefore, the image after the distortion aberration is electrically corrected becomes rough. Therefore, it is not preferable to fall below the lower limit. It is preferable to generate a negative distortion at the wide angle end. FIGS. 15A to 15D show examples of DT _min . 15A to 15D are aberration diagrams showing distortion aberration.

  Furthermore, it is preferable that the following conditional expression (13-2) is satisfied. By satisfying this condition, it is possible to widen the angle of view without making the image rough.

−30 <DT _min <0 (13-2)
Furthermore, it is preferable that the following conditional expression (13-3) is satisfied. By satisfying this condition, it is possible to widen the angle of view without making the image rough.

−27 <DT _min <−5 (13-3)
A twenty-sixth variable power optical system of the present invention is characterized in that, in the first to twenty-fifth variable power optical systems, distortion aberration generated in the optical system is electrically corrected.

  Hereinafter, the reason and operation of the above-described configuration in the twenty-sixth variable magnification optical system will be described.

  If the distortion is to be corrected well by the optical system, the number of lenses increases and the optical system becomes larger. It is preferable that the optical system can be made more compact by electrically correcting distortion that cannot be corrected by the optical system.

  Since the retro focus type has a large negative distortion at the wide-angle end, it is easy to increase the angle of view and increase the magnification when electrically correcting the image distortion. Therefore, the retro focus type is preferable as the optical system.

  The twenty-seventh variable magnification optical system of the present invention is characterized in that, in the first to twenty-sixth variable magnification optical systems, lateral chromatic aberration generated in the optical system is electrically corrected.

  Hereinafter, the reason and action of the above-described configuration in the twenty-seventh variable magnification optical system will be described.

  By constituting the first lens group with one negative lens, lateral chromatic aberration is greatly generated at the wide angle end. At this time, if it is attempted to satisfactorily correct lateral chromatic aberration with the optical system, the number of lenses increases and the optical system becomes larger. Therefore, it is preferable to electrically correct lateral chromatic aberration that cannot be corrected by the optical system. By doing in this way, an optical system can be made more compact. In order to electrically correct the chromatic aberration of magnification, the size of the image for each color may be matched. To change the size of the image, a correction method for field curvature may be used.

  A twenty-eighth variable magnification optical system according to the present invention is characterized in that, in the first to twenty-seventh variable magnification optical system, an organic-inorganic composite material is used as an optical material of at least one optical element constituting the optical system. It is.

  The reason and action of the above configuration in the 28th variable magnification optical system will be described below.

  When an organic-inorganic composite material is used as the optical material of the optical element, various optical properties (refractive index, wavelength dispersion) are exhibited depending on the type and abundance ratio of the organic component and the inorganic component (obtained). ). Therefore, by blending the organic component and the inorganic component in an arbitrary ratio, various optical characteristics can be obtained, and various aberrations can be corrected with a smaller number of sheets, that is, at a low cost and a small size.

  A twenty-ninth variable magnification optical system of the present invention is the twenty-eighth variable magnification optical system, wherein the organic-inorganic composite includes zirconia nanoparticles.

  The 30th variable magnification optical system of the present invention is the 28th variable magnification optical system, characterized in that the organic-inorganic composite includes nanoparticles of zirconia and alumina.

  The thirty-first variable magnification optical system of the present invention is the twenty-eighth variable magnification optical system, wherein the organic-inorganic composite includes niobium oxide nanoparticles.

  A thirty-second variable magnification optical system of the present invention is the twenty-eighth variable magnification optical system, wherein the organic-inorganic composite includes a hydrolyzate of zirconium alkoxide and alumina nanoparticles.

  In the 29th to 32nd variable power optical systems of the present invention, the reason why the above configuration is adopted and the operation thereof will be described. The nanoparticles of these materials are examples of inorganic components. Then, by dispersing such nanoparticles in an organic component plastic at a predetermined abundance ratio, various optical characteristics (refractive index, wavelength dispersibility) can be expressed.

  The electronic apparatus of the present invention is characterized by having first to thirty-second variable power optical systems and an electronic image pickup device arranged on the image side thereof.

  The reason why the above-described configuration is adopted in the electronic apparatus of the present invention and the operation thereof will be described. The above variable magnification optical system of the present invention is small and low-cost. Therefore, in an electronic device equipped with such a variable magnification optical system as an imaging optical system, it is possible to reduce the size and cost of the device. Electronic devices include digital cameras, video cameras, digital video units, personal computers, mobile computers, mobile phones, portable information terminals, and the like.

  According to the present invention, it is possible to obtain a variable magnification optical system that can effectively achieve both cost reduction and downsizing, and electronic devices using the same can also be reduced in cost and size. Coexistence becomes possible effectively.

  Examples 1 to 7 of the variable magnification optical system (zoom lens) of the present invention will be described below with reference to the drawings. FIGS. 1 to 7 show lens cross sections along the optical axes 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 7, respectively. In each figure, G1 is the first lens group, S is the aperture stop, G2 is the second lens group, G3 is the third lens group, G4 is the fourth lens group, F is the near-infrared cut filter, low-pass filter, and electronic imaging A plane parallel plate group such as a cover glass of the element, I denotes an image plane. In addition, the spherical aberration (SA), astigmatism (AS), distortion aberration (at the wide-angle end (a), the intermediate state (b), the telephoto end (c) at the time of focusing on an object point at infinity according to Examples 1-7. Aberration diagrams of DT) and lateral chromatic aberration (CC) are shown in FIGS. In these aberration diagrams, “FIY” represents the image height.

  As shown in FIG. 1, the variable magnification optical system according to the first embodiment includes, in order from the object side, a first lens group G1, an aperture stop S, a second lens group G2, a third lens group G3, and a fourth lens group. It consists of a lens group G4. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 moves monotonously to the object side together with the aperture stop S, and the third lens group G3 is the second lens group G3. The fourth lens group G4 is fixed while moving to the object side while slightly widening the distance from the lens group G2.

  The first lens group G1 is composed of a biconcave negative lens and has negative power. Both surfaces of this biconcave negative lens are aspheric.

  The second lens group G2 is composed of a biconvex positive lens and has positive power. Both surfaces of this biconvex positive lens are aspheric.

  The third lens group G3 is composed of a biconcave negative lens and has negative power. The image side surface of this biconcave negative lens is aspheric.

  The fourth lens group G4 includes a positive meniscus lens having a concave surface directed toward the object side, and has positive power. The image side surface of the positive meniscus lens is aspheric.

  The lenses of this example are all made of a resin material except that the biconvex positive lens of the second lens group G2 is made of glass.

  As shown in FIG. 2, the variable magnification optical system of the second embodiment includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. It consists of a lens group G4. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 moves monotonously to the object side together with the aperture stop S, and the third lens group G3 is the second lens group G3. The fourth lens group G4 is fixed, with the distance to the lens group G2 being slightly narrowed and then moved toward the object side.

  The first lens group G1 is composed of a biconcave negative lens and has negative power. Both surfaces of this biconcave negative lens are aspheric.

  The second lens group G2 is composed of a biconvex positive lens and has positive power. Both surfaces of this biconvex positive lens are aspheric.

  The third lens group G3 is composed of a biconcave negative lens and has negative power. The image side surface of this biconcave negative lens is aspheric.

  The fourth lens group G4 includes a positive meniscus lens having a concave surface directed toward the object side, and has positive power. The image side surface of the positive meniscus lens is aspheric.

  The lenses of this example are all made of a resin material except that the biconvex positive lens of the second lens group G2 is made of glass.

  As shown in FIG. 3, the zoom optical system of Example 3 includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. It consists of a lens group G4. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 moves monotonously to the object side together with the aperture stop S, and the third lens group G3 is the second lens group G3. The fourth lens group G4 is fixed, with the distance to the lens group G2 being slightly narrowed and then moved toward the object side.

  The first lens group G1 is composed of a biconcave negative lens and has negative power. Both surfaces of this biconcave negative lens are aspheric.

  The second lens group G2 is composed of a biconvex positive lens and has positive power. Both surfaces of this biconvex positive lens are aspheric.

  The third lens group G3 is composed of a biconcave negative lens and has negative power. The image side surface of this biconcave negative lens is aspheric.

  The fourth lens group G4 includes a positive meniscus lens having a concave surface directed toward the object side, and has positive power. The image side surface of the positive meniscus lens is aspheric.

  The lenses of this example are all made of a resin material except that the biconcave negative lens of the first lens group G1 and the biconvex positive lens of the second lens group G2 are made of glass.

  As shown in FIG. 4, the variable magnification optical system of the fourth embodiment includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. It consists of a lens group G4. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 moves monotonously to the object side together with the aperture stop S, and the third lens group G3 is the second lens group G3. The fourth lens group G4 is fixed, with the distance to the lens group G2 being slightly narrowed and then moved toward the object side.

  The first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a concave surface directed toward the image side, and has negative power. Both surfaces of the biconcave negative lens and the image side surface of the positive meniscus lens are aspheric.

  The second lens group G2 is composed of a biconvex positive lens and has positive power. Both surfaces of this biconvex positive lens are aspheric.

  The third lens group G3 is composed of a biconcave negative lens and has negative power. The image side surface of this biconcave negative lens is aspheric.

  The fourth lens group G4 includes a positive meniscus lens having a concave surface directed toward the object side, and has positive power. The image side surface of the positive meniscus lens is aspheric.

  The lenses of this example are all made of a resin material except that the biconcave negative lens of the first lens group G1 and the biconvex positive lens of the second lens group G2 are made of glass.

  As shown in FIG. 5, the variable magnification optical system of Example 5 includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. It consists of a lens group G4. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 moves monotonously to the object side together with the aperture stop S, and the third lens group G3 is the second lens group G3. The fourth lens group G4 is fixed, with the distance to the lens group G2 being slightly narrowed and then moved toward the object side.

  The first lens group G1 is composed of a biconcave negative lens and has negative power. Both surfaces of this biconcave negative lens are aspheric.

  The second lens group G2 is composed of a biconvex positive lens and has positive power. Both surfaces of this biconvex positive lens are aspheric.

  The third lens group G3 is composed of a biconcave negative lens and has negative power. The image side surface of this biconcave negative lens is aspheric.

  The fourth lens group G4 includes a positive meniscus lens having a concave surface directed toward the object side, and has positive power. The image side surface of the positive meniscus lens is aspheric.

  The lenses of this example are all made of a resin material except that the biconvex positive lens of the second lens group G2 and the biconcave negative lens of the third lens group G3 are made of glass.

  As shown in FIG. 6, the zoom optical system of Example 6 includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. It consists of a lens group G4. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 moves monotonously to the object side together with the aperture stop S, and the third lens group G3 is the second lens group G3. The fourth lens group G4 is fixed, with the distance to the lens group G2 being slightly narrowed and then moved toward the object side.

  The first lens group G1 includes a negative meniscus lens having a concave surface directed toward the image side, and has negative power. Both surfaces of this negative meniscus lens are aspheric.

  The second lens group G2 is composed of a biconvex positive lens and has positive power. Both surfaces of this biconvex positive lens are aspheric.

  The third lens group G3 is composed of a biconcave negative lens and has negative power. The image side surface of this biconcave negative lens is aspheric.

  The fourth lens group G4 includes a positive meniscus lens having a concave surface directed toward the object side, and has positive power. The image side surface of the positive meniscus lens is aspheric.

  The lenses of this example are all made of glass except that the negative meniscus lens of the first lens group G1 and the biconvex positive lens of the second lens group G2 are made of a resin material.

  As shown in FIG. 7, the variable magnification optical system of the seventh embodiment includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. It consists of a lens group G4. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a concave locus on the object side, and is positioned closer to the image side than the wide-angle end at the telephoto end, and the second lens group G2 It moves monotonously with the aperture stop S toward the object side, the third lens group G3 moves integrally with the second lens group G2, and the fourth lens group G4 is fixed.

  The first lens group G1 is composed of a biconcave negative lens and has negative power. Both surfaces of this biconcave negative lens are aspheric.

  The second lens group G2 is composed of a biconvex positive lens and has positive power. Both surfaces of this biconvex positive lens are aspheric.

  The third lens group G3 is composed of a biconcave negative lens and has negative power. The image side surface of this biconcave negative lens is aspheric.

  The fourth lens group G4 includes a positive meniscus lens having a concave surface directed toward the object side, and has positive power. The image side surface of the positive meniscus lens is aspheric.

  The lens of the present embodiment is all made of glass except that the biconvex positive lens of the second lens group G2 is made of a resin material.

Hereinafter, numerical data of each embodiment described above, but the symbols are outside the above, f is the entire system in terms of focal length, F _NO is the ray incident on the F-number, omega 60% position of the maximum image height Hankaku Angle, WE is a wide angle end, ST is an intermediate state, TE is a telephoto end, r ₁ , r _2, ... Are curvature radii of lens surfaces, d ₁ , d _2, are intervals between the lens surfaces, n _d1 , n _d2 ... d-line refractive index of each lens, ν _d1, ν _d2 ... is the Abbe number of each lens. Here, the converted focal length is a focal length defined in the same manner as the conditional expression (4) in each state. 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
Here, r is a paraxial radius of curvature, K is a conical coefficient, and A ₄ , A ₆ , and A ₈ are fourth-order, sixth-order, and eighth-order aspheric coefficients, respectively.

Example 1
r ₁ = -6.183 (aspherical surface) d ₁ = 0.50 n _d1 = 1.52542 ν _d1 = 55.78
r ₂ = 5.256 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = 0.11
r ₄ = 2.506 (aspherical surface) d ₄ = 1.40 n _d2 = 1.69350 ν _d2 = 53.21
r ₅ = -3.911 (aspherical surface) d ₅ = (variable)
r ₆ = −10.763 d ₆ = 0.69 n _d3 = 1.60687 ν _d3 = 27.03
r ₇ = 2.550 (aspherical surface) d ₇ = (variable)
r ₈ = -10.931 d ₈ = 0.93 n _d4 = 1.52542 ν _d4 = 55.78
r ₉ = -3.297 (aspherical surface) d ₉ = 1.47
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = -8.832
A ₄ = -1.6811 × 10 ^-2
A ₆ = 4.6095 × 10 ^-3
A ₈ = -3.7318 × 10 ^-4
Second side K = 2.683
A ₄ = -1.7005 × 10 ^-2
A ₆ = 4.8706 × 10 ^-3
A ₈ = -8.7160 × 10 ^-5
4th surface K = -1.446
A ₄ = 7.1820 × 10 ^-3
A ₆ = -1.3597 × 10 ^-3
A ₈ = -8.9543 × 10 ^-4
Fifth side K = 4.998
A ₄ = 3.1231 × 10 ^-2
A ₆ = -3.7519 × 10 ^-3
A ₈ = 3.3416 × 10 ^-3
Surface 7 K = 0.398
A ₄ = -6.3058 × 10 ^-3
A ₆ = 1.3348 × 10 ^-2
A ₈ = -2.0305 × 10 ^-3
Surface 9 K = -5.648
A ₄ = -1.2285 × 10 ^-2
A ₆ = 1.4116 × 10 ^-3
A ₈ = -1.5701 × 10 ^-4
Zoom data (∞)
WE ST TE
tan ω 0.464 0.268 0.155
f (mm) 2.912 5.044 8.737
F _NO 2.80 3.62 4.70
d ₂ 3.80 2.08 0.29
d ₅ 0.38 0.39 0.72
d ₇ 0.99 2.71 4.17
Y _h = 2.25mm.

Example 2
r ₁ = -32.606 (aspherical surface) d ₁ = 0.50 n _d1 = 1.52542 ν _d1 = 55.78
r ₂ = 2.845 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = -0.16
r ₄ = 1.761 (aspherical surface) d ₄ = 1.00 n _d2 = 1.74320 ν _d2 = 49.34
r ₅ = -3.652 (aspherical surface) d ₅ = (variable)
r ₆ = -8.689 d ₆ = 0.50 n _d3 = 1.60687 ν _d3 = 27.03
r ₇ = 1.972 (aspherical surface) d ₇ = (variable)
r ₈ = -7.397 d ₈ = 0.90 n _d4 = 1.52542 ν _d4 = 55.78
r ₉ = -2.804 (aspherical surface) d ₉ = 1.04
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = 339.509
A ₄ = -5.0584 × 10 ^-2
A ₆ = 1.5427 × 10 ^-2
A ₈ = -1.3268 × 10 ^-3
Second side K = -2.129
A ₄ = -5.2582 × 10 ^-2
A ₆ = 1.7185 × 10 ^-2
A ₈ = 1.0183 × 10 ^-3
4th surface K = -0.740
A ₄ = 1.7275 × 10 ^-2
A ₆ = -3.1227 × 10 ^-3
A ₈ = 1.7476 × 10 ^-2
Fifth side K = -0.368
A ₄ = 6.5061 × 10 ^-2
A ₆ = -2.4639 × 10 ^-2
A ₈ = 4.5010 × 10 ^-2
Surface 7 K = 1.724
A ₄ = -3.3630 × 10 ^-2
A ₆ = 3.5465 × 10 ^-2
A ₈ = -2.4462 × 10 ^-2
Surface 9 K = 0.404
A ₄ = 1.3104 × 10 ^-2
A ₆ = -2.7380 × 10 ^-3
A ₈ = 3.2071 × 10 ^-4
Zoom data (∞)
WE ST TE
tan ω 0.464 0.328 0.232
f (mm) 2.912 4.119 5.824
F _NO 2.80 3.30 3.92
d ₂ 2.03 1.23 0.36
d ₅ 0.12 0.10 0.16
d ₇ 0.73 1.55 2.36
Y _h = 2.25mm.

Example 3
r ₁ = -9.655 (aspherical surface) d ₁ = 0.50 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = 4.784 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = 0.08
r ₄ = 2.585 (aspherical surface) d ₄ = 1.21 n _d2 = 1.69350 ν _d2 = 53.21
r ₅ = -3.456 (aspherical surface) d ₅ = (variable)
r ₆ = -9.610 d ₆ = 1.01 n _d3 = 1.60687 ν _d3 = 27.03
r ₇ = 2.239 (aspherical surface) d ₇ = (variable)
r ₈ = -20.331 d ₈ = 1.08 n _d4 = 1.52542 ν _d4 = 55.78
r ₉ = -3.315 (aspherical surface) d ₉ = 1.20
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = 0.000
A ₄ = -1.8649 × 10 ^-2
A ₆ = 4.3938 × 10 ^-3
A ₈ = -3.0112 × 10 ^-4
Second side K = 0.000
A ₄ = -2.1364 × 10 ^-2
A ₆ = 4.9041 × 10 ^-3
A ₈ = -5.0578 × 10 ^-5
4th surface K = -2.226
A ₄ = 9.2902 × 10 ^-3
A ₆ = -2.4966 × 10 ^-3
A ₈ = 0
Fifth side K = 0.000
A ₄ = 1.8077 × 10 ^-2
A ₆ = -5.3925 × 10 ^-3
A ₈ = 5.3371 × 10 ^-4
Surface 7 K = -0.294
A ₄ = -2.2536 × 10 ^-3
A ₆ = 1.2288 × 10 ^-2
A ₈ = -1.1899 × 10 ^-3
The ninth side K = -0.992
A ₄ = 4.5567 × 10 ^-3
A ₆ = -1.1044 × 10 ^-3
A ₈ = 5.8436 × 10 ^-5
Zoom data (∞)
WE ST TE
tan ω 0.464 0.271 0.155
f (mm) 2.912 4.982 8.737
F _NO 2.80 3.66 4.83
d ₂ 3.98 2.25 0.22
d ₅ 0.28 0.22 0.39
d ₇ 0.77 2.57 4.43
Y _h = 2.25mm.

Example 4
r ₁ = -4.079 (aspherical surface) d ₁ = 0.50 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = 8.948 (aspherical surface) d ₂ = 0.26
r ₃ = 6.961 d ₃ = 0.50 n _d2 = 1.58423 ν _d2 = 30.49
r ₄ = 8.499 (aspherical surface) d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.05
r ₆ = 2.577 (aspherical surface) d ₆ = 1.33 n _d3 = 1.69350 ν _d3 = 53.21
r ₇ = -3.853 (aspherical surface) d ₇ = (variable)
r ₈ = -7.684 d ₈ = 0.65 n _d4 = 1.60687 ν _d4 = 27.03
r ₉ = 2.484 (aspherical surface) d ₉ = (variable)
r ₁₀ = -77.410 d ₁₀ = 1.07 n _d5 = 1.52542 ν _d5 = 55.78
r ₁₁ = -3.896 (aspherical surface) d ₁₁ = 1.51
r ₁₂ = ∞ d ₁₂ = 0.50 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₃ = ∞
Aspheric coefficient 1st surface K = -5.031
A ₄ = 9.1900 × 10 ^-4
A ₆ = 2.3688 × 10 ^-4
A ₈ = -2.0369 × 10 ^-5
Second side K = 0.000
A ₄ = 6.9305 × 10 ^-3
A ₆ = -2.9645 × 10 ^-4
A ₈ = 0
4th surface K = 3.002
A ₄ = -1.0237 × 10 ^-4
A ₆ = 5.8425 × 10 ^-4
A ₈ = 3.3321 × 10 ^-5
6th surface K = -1.455
A ₄ = 7.1596 × 10 ^-3
A ₆ = -7.5701 × 10 ^-4
A ₈ = 7.2848 × 10 ^-5
Surface 7 K = 4.302
A ₄ = 2.9455 × 10 ^-2
A ₆ = -4.3530 × 10 ^-3
A ₈ = 2.0768 × 10 ^-3
Surface 9 K = 0.462
A ₄ = -9.8796 × 10 ^-3
A ₆ = 1.1006 × 10 ^-2
A ₈ = -4.9352 × 10 ^-4
11th surface K = -2.202
A ₄ = 6.4804 × 10 ^-4
A ₆ = -2.5619 × 10 ^-4
A ₈ = -9.1878 × 10 ^-6
Zoom data (∞)
WE ST TE
tan ω 0.464 0.268 0.155
f (mm) 2.912 5.044 8.737
F _NO 2.80 3.64 4.70
d ₄ 4.44 2.41 0.27
d ₇ 0.30 0.29 0.51
d ₉ 1.41 3.45 5.37
Y _h = 2.25mm.

Example 5
r ₁ = -8.223 (aspherical surface) d ₁ = 0.50 n _d1 = 1.52542 ν _d1 = 55.78
r ₂ = 6.042 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = 0.00
r ₄ = 2.602 (aspherical surface) d ₄ = 1.26 n _d2 = 1.74320 ν _d2 = 49.34
r ₅ = -3.543 (aspherical surface) d ₅ = (variable)
r ₆ = -8.926 d ₆ = 0.69 n _d3 = 1.68893 ν _d3 = 31.07
r ₇ = 2.496 (aspherical surface) d ₇ = (variable)
r ₈ = -13.204 d ₈ = 0.98 n _d4 = 1.52542 ν _d4 = 55.78
r ₉ = -3.213 (aspherical surface) d ₉ = 1.35
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = -10.658
A ₄ = -1.3563 × 10 ^-2
A ₆ = 2.8485 × 10 ^-3
A ₈ = -1.7401 × 10 ^-4
Second side K = 1.931
A ₄ = -1.3665 × 10 ^-2
A ₆ = 2.8113 × 10 ^-3
A ₈ = 3.6936 × 10 ^-5
4th surface K = -1.594
A ₄ = 6.3703 × 10 ^-3
A ₆ = -1.4234 × 10 ^-3
A ₈ = -8.5820 × 10 ^-4
Fifth side K = 3.729
A ₄ = 3.1487 × 10 ^-2
A ₆ = -6.1491 × 10 ^-3
A ₈ = 1.5899 × 10 ^-3
Surface 7 K = 0.548
A ₄ = -9.0292 × 10 ^-3
A ₆ = 1.2875 × 10 ^-2
A ₈ = -1.1363 × 10 ^-3
The ninth side K = -3.124
A ₄ = -3.0035 × 10 ^-3
A ₆ = 1.3365 × 10 ^-4
A ₈ = -1.4921 × 10 ^-5
Zoom data (∞)
WE ST TE
tan ω 0.464 0.268 0.155
f (mm) 2.912 5.044 8.737
F _NO 2.80 3.67 4.80
d ₂ 4.37 2.49 0.40
d ₅ 0.22 0.16 0.29
d ₇ 1.14 3.08 5.05
Y _h = 2.25mm.

Example 6
r ₁ = 7.747 (aspherical surface) d ₁ = 0.62 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = 2.692 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = 0.00
r ₄ = 2.784 (aspherical surface) d ₄ = 1.37 n _d2 = 1.69350 ν _d2 = 53.21
r ₅ = -4.121 (aspherical surface) d ₅ = (variable)
r ₆ = -8.694 d ₆ = 1.40 n _d3 = 1.60687 ν _d3 = 27.03
r ₇ = 2.109 (aspherical surface) d ₇ = (variable)
r ₈ = -583.06 d ₈ = 1.35 n _d4 = 1.52542 ν _d4 = 55.78
r ₉ = -3.099 (aspherical surface) d ₉ = 0.80
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = 0.000
A ₄ = -3.1844 × 10 ^-2
A ₆ = 4.5979 × 10 ^-3
A ₈ = -2.2469 × 10 ^-4
Second side K = 0.000
A ₄ = -4.3997 × 10 ^-2
A ₆ = 6.1072 × 10 ^-3
A ₈ = -3.0480 × 10 ^-4
4th surface K = -1.718
A ₄ = 6.1590 × 10 ^-3
A ₆ = -3.5451 × 10 ^-5
A ₈ = 0
Fifth side K = 0.000
A ₄ = 1.4067 × 10 ^-2
A ₆ = -1.3236 × 10 ^-3
A ₈ = -4.0202 × 10 ^-5
Surface 7 K = -0.880
A ₄ = 4.0675 × 10 ^-3
A ₆ = 8.2640 × 10 ^-3
A ₈ = 7.3958 × 10 ^-4
Surface 9 K = -1.385
A ₄ = 7.2789 × 10 ^-3
A ₆ = -1.6320 × 10 ^-3
A ₈ = 1.0057 × 10 ^-4
Zoom data (∞)
WE ST TE
tan ω 0.386 0.209 0.120
f (mm) 3.501 6.451 11.226
F _NO 2.80 4.01 5.41
d ₂ 5.14 2.76 0.30
d ₅ 0.40 0.29 0.42
d ₇ 0.73 3.22 5.56
Y _h = 2.25mm.

Example 7
r ₁ = -10.830 (aspherical surface) d ₁ = 0.50 n _d1 = 1.52542 ν _d1 = 55.78
r ₂ = 5.001 (aspherical surface) d ₂ = (variable)
r ₃ = ∞ (aperture) d ₃ = 0.12
r ₄ = 2.379 (aspherical surface) d ₄ = 1.40 n _d2 = 1.69350 ν _d2 = 53.21
r ₅ = -4.330 (aspherical surface) d ₅ = (variable)
r ₆ = -12.684 d ₆ = 0.50 n _d3 = 1.60687 ν _d3 = 27.03
r ₇ = 2.616 (aspherical surface) d ₇ = (variable)
r ₈ = -4.500 d ₈ = 0.89 n _d4 = 1.52542 ν _d4 = 55.78
r ₉ = -2.437 (aspherical surface) d ₉ = 0.80
r ₁₀ = ∞ d ₁₀ = 0.50 n _d5 = 1.51633 ν _d5 = 64.14
r ₁₁ = ∞
Aspheric coefficient 1st surface K = 1.353
A ₄ = -1.9133 × 10 ^-2
A ₆ = 3.9701 × 10 ^-3
A ₈ = -2.4010 × 10 ^-4
Second side K = -1.448
A ₄ = -2.0173 × 10 ^-2
A ₆ = 4.1109 × 10 ^-3
A ₈ = 1.4332 × 10 ^-5
4th surface K = -1.242
A ₄ = 8.6803 × 10 ^-3
A ₆ = -1.8366 × 10 ^-3
A ₈ = 7.1887 × 10 ^-4
Fifth side K = 4.369
A ₄ = 3.0765 × 10 ^-2
A ₆ = -9.1609 × 10 ^-3
A ₈ = 3.5814 × 10 ^-3
Surface 7 K = 0.376
A ₄ = -4.4877 × 10 ^-3
A ₆ = 2.1909 × 10 ^-2
A ₈ = -3.8175 × 10 ^-3
Surface 9 K = -2.625
A ₄ = -7.2840 × 10 ^-3
A ₆ = -3.3813 × 10 ^-4
A ₈ = -2.7375 × 10 ^-5
Zoom data (∞)
WE ST TE
tan ω 0.464 0.268 0.155
f (mm) 2.912 5.044 8.737
F _NO 2.80 3.67 4.79
d ₂ 4.15 1.89 0.28
d ₅ 0.38 0.38 0.38
d ₇ 1.06 2.32 4.73
Y _h = 2.25mm.

  Next, the values of conditional expressions (1) to (13) in the above embodiments will be shown.

Conditional expression (1) (2) (3) (4) (5) (6) (7) Example 1 -0.43 0.08 55.78 1.83 3.2 × 10 ^-6 -0.22 53.21
Example 2 -0.39 0.84 55.78 1.70 6.2 × 10 ^-6 -0.35 49.34
Example 3 -0.50 0.34 81.54 2.19 3.2 × 10 ^-6 -0.14 53.21
Example 4 -0.55 -0.35 81.54 1.91 3.2 × 10 ^-6 -0.20 53.21
Example 5 -0.50 0.15 55.78 2.25 6.2 × 10 ^-6 -0.15 49.34
Example 6 -0.68 2.07 81.54 2.47 3.2 × 10 ^-6 -0.19 53.21
Example 7 -0.42 0.37 55.78 2.21 3.2 × 10 ^-6 -0.29 53.21
.

Conditional expression (8) (9) (10) (11) (12) (13)
Example 1 0.83 0.62 27.03 1.86 55.78 -25.1
Example 2 0.60 0.63 27.03 2.22 55.78 -19.4
Example 3 0.80 0.62 27.03 1.39 55.78 -23.0
Example 4 0.84 0.51 23.78 1.11 55.78 -24.1
Example 5 0.76 0.56 31.07 1.64 55.78 -24.7
Example 6 0.74 0.61 27.03 1.01 55.78 -6.2
Example 7 0.83 0.66 27.03 3.36 55.78 -24.9
.

  By the way, in all the zoom lenses (variable magnification optical systems) of the above embodiments, distortion is relatively large. Therefore, when the subject image information is taken in via the electronic image sensor, the video signal output from the electronic image sensor includes the distortion information. That is, image data having distortion is taken into the electronic imaging apparatus. An example of such optical distortion is barrel distortion as shown in FIG. In the case of the barrel distortion, the distortion is such that the image on the screen 101 that should originally be at the position indicated by the broken line becomes the image on the screen 102 formed at the solid line position.

  In all the embodiments described above, such distortion is electrically corrected. The electrical correction method will be described below.

In order to correct the distortion in the video signal with optical distortion captured through the electronic image pickup device as described above, first, the video signal is converted into a digital signal and written in the image memory. Then, the distortion is corrected on the image memory by reading according to the distortion characteristics. In FIG. 16, when there is no distortion, the lattice-shaped image is an image 101 indicated by a broken line. On the other hand, when there is distortion, the lattice-shaped image is an image 102 indicated by a solid line. In a state where optical distortion occurs in the optical system as in the zoom lens of the present invention, the image 101 indicated by the broken line is stored in the image memory like the solid line image 102 due to the optical distortion described above. Therefore, in order to correct this distortion, when the pre-correction image data is read from the image memory, the pre-correction image data stored at the point P _{a at the} timing at which the point P _A should be read, and the point P _B reading the uncorrected image data stored in P _b point timing to read out, similarly to Bae-out timing of reading the P _D point uncorrected image data stored in the P _d points, respectively. In this way, the pre-correction image 102 is read out as an image of the original grid-like screen 101 without distortion indicated by a broken line, so that an image with corrected optical distortion is displayed.

As a distortion correction method, other points may be corrected on the basis of the _Px point. In this case, the outermost frame (outer side) of the corrected image 103 is as indicated by a one-dot chain line. As can be seen from the figure, the point P _{x is the} point P _X and does not change before and after the correction. On the other hand, for example, so that the P _Y point corresponding to P _y points. Further, as can be seen from the figure, the image of the alternate long and short dash line is a reduced image of the image indicated by the dotted line. Therefore, each point of the image indicated by the solid line is corrected to a position corresponding to the ratio between the reduced outer frame 103 ′ and the broken outer frame 102 ′.

  FIG. 17 is a block configuration diagram of an apparatus having an image processing function for performing optical distortion correction. In this apparatus, first, a subject image is formed on the imaging surface of a CCD (electronic imaging device) 2 via the zoom lens 1 of the present invention. The subject image formed on the imaging surface of the CCD 2 includes the optical distortion as described above. This subject image is converted into an electrical signal by the CCD 2. The electrical signal from the CCD 2 is subjected to predetermined processing by the imaging process circuit 3 and is supplied to the A / D conversion circuit 4 as a video signal. The video signal converted into a digital signal by the A / D conversion circuit 4 is stored in the image memory 5. Writing and reading of signals to and from the image memory 5 are controlled by the write control circuit 10 and the read control circuit 12A.

  The SSG (synchronization signal generation) circuit 9 generates a reference timing signal. The SSG (synchronization signal generation) circuit 9 supplies this reference timing signal to a TG (timing generation) circuit 8, the imaging process circuit 3, the write control circuit 10, and the read control circuit 12A, which will be described later. The TG circuit 8 sends readout timing signals in the horizontal (H) direction and vertical (V) direction from the SSG circuit 9 to the CCD 2. The correction amount ROM 13A stores correction amount data determined in advance for each part of the screen. What is stored as the predetermined correction amount is, for example, a correction amount address value for correcting optical distortion determined by the relationship between the position on the solid line and the position on the broken line, as shown in FIG.

  Then, a signal (data) is read from the image memory 5 by the read signal output from the read control circuit 12A. At this time, the signal is read from the image memory 5 to correct the optical distortion. The read signal is interpolated by the interpolation processing circuit 6, converted to an analog signal by the D / A converter 7, and output.

  In the case of a digital camera (electronic camera), the image memory 5 may not have enough room. In such a case, the timing may be changed for a time corresponding to the optical distortion correction amount before storing in the image memory 5, that is, when reading the video signal from the CCD 2.

  Next, the chromatic aberration of magnification can also be corrected to the electrical system by performing distortion correction similar to the above for each color separation image. In all the embodiments described above, not only distortion aberration but also lateral chromatic aberration are electrically corrected simultaneously.

  By the way, in the variable magnification optical system of the above embodiment, glass or a resin material is used for the lens, but an organic-inorganic composite material may be used instead. The organic-inorganic composite usable in the present invention will be described.

  The organic-inorganic composite is a composite in which an organic component and an inorganic component are mixed and combined at a molecular level or nanoscale. Its form is (1) a structure in which a polymer matrix composed of an organic skeleton and a matrix composed of an inorganic skeleton are intertwined with each other and penetrated into each other's matrix. There are those in which inorganic fine particles (so-called nanoparticles) sufficiently smaller than the light wavelength of the scale are uniformly dispersed, and (3) those having a composite structure of these. Some interaction acts between the organic component and the inorganic component, such as intermolecular forces such as hydrogen bonds, dispersion forces, and Coulomb forces, and attractive forces due to covalent bonds, ionic bonds, and π electron cloud interactions. In the organic-inorganic composite, as described above, the organic component and the inorganic component are mixed at a molecular level or a scale region smaller than the wavelength of light. For this reason, there is almost no influence on light scattering, and a transparent body can be obtained. Further, as derived from the Maxwell equation, the material reflects the optical characteristics of the organic component and the inorganic component. Therefore, various optical characteristics (refractive index, wavelength dispersion) are developed according to the types and abundance ratios of the organic component and the inorganic component. From this, various optical characteristics can be obtained by blending the organic component and the inorganic component in an arbitrary ratio.

Table 1 below shows a composition example of an organic-inorganic composite of acrylate resin (ultraviolet curable) and zirconia (ZrO ₂ ) nanoparticles. Table 2 shows a composition example of an organic-inorganic composite of an acrylate resin and zirconia (ZrO ₂ ) / alumina (Al ₂ O ₃ ) nanoparticles. Table 3 shows a composition example of an organic-inorganic composite of acrylate resin and niobium oxide (Nb ₂ O ₅ ) nanoparticles. Table 4 shows a composition example of an organic-inorganic composite of acrylate resin, zirconium alkoxide, and alumina (Al ₂ O ₃ ) nanoparticles.

Table 1
┌────┬────┬────┬┬────┬────┬────┬─────┐
│ zirconia _{│n d │ν d │n C │n F} │n g │ Notes │
│A content│ │ │ │ │ │ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0 │1.49236 │57.85664 │1.48981 │1.49832 │1.50309 │Acrylic │
│ │ │ │ │ │ │ 100% │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.1 │1.579526 │54.85037 │1.57579 │1.586355 │1.59311 │ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.2 │1.662128 │53.223 │1.657315 │1.669756 │1.678308│ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.3 │1.740814│52.27971│1.735014│1.749184│1.759385│ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.4 │1.816094│51.71726│1.809379│1.825159│1.836887│ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.5 │1.888376 │51.3837 │1.880807 │1.898096 │1.911249│ │
└────┴────┴────┴┴────┴────┴────┴─────┘
.

Table 2
┌───┬───┬────┬────┬────┬────┬┬────┬────┐
_{│Al 2 O 3 │ZrO 2 │n d} │ν d │n C │n F │n g │ Remarks │
│ presence rate │ presence rate │ │ │ │ │ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.1 │0.4 │1.831515│53.56672│1.824851│1.840374│1.851956│Acryl│
│ │ │ │ │ │ │ │50% │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.2 │0.3 │1.772832│56.58516│1.767125│1.780783│1.790701│ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.3 │0.2 │1.712138│60.97687│1.707449│1.719127│1.727275│ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.4 │0.1 │1.649213│67.85669│1.645609│1.655177│1.661429│ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.2 │0.2 │1.695632│58.32581│1.690903│1.702829│1.774891│ │
└───┴───┴────┴────┴────┴────┴┴────┴────┘
.

Table 3
┌───┬───┬────┬────┬────┬┬────┬────┐
_{│Nb 2 O 5 │Al 2 O 3} │n d │ν d │n C │n F │n g │
│Content│Content│ │ │ │ │ │
├───┼───┼────┼────┼────┼┼────┼────┤
│0.1 │ 0 │1.589861│29.55772│1.584508│1.604464│1.617565│
├───┼───┼────┼────┼────┼┼────┼────┤
│0.2 │ 0 │1.681719 │22.6091 │1.673857 │1.70401 │1.724457│
├───┼───┼────┼────┼────┼┼────┼────┤
│0.3 │ 0 │1.768813 │19.52321 │1.758673 │1.798053 │1.8251 │
├───┼───┼────┼────┼────┼┼────┼────┤
│0.4 │ 0 │1.851815 │17.80818 │1.839583 │1.887415 │1.920475│
├───┼───┼────┼────┼────┼┼────┼────┤
│0.5 │ 0 │1.931253 │16.73291 │1.91708 │1.972734 │2.011334│
└───┴───┴────┴────┴────┴┴────┴────┘
.

Table 4
┌─────┬──────┬────┬────┬┬────┬────┐
│Al ₂ O ₃ (film) │ zirconia A _{│n d │ν d │n C │n F} │
│Content │Lucoxide │ │ │ │ │
├─────┼──────┼────┼────┼┼────┼────┤
│ 0 │ 0.3 │1.533113│58.39837│1.530205│1.539334│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.1 │ 0.27 │1.54737 │62.10192│1.544525│1.553339│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.2 │ 0.24 │1.561498│66.01481│1.558713│1.567219│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.3 │ 0.21 │1.575498│70.15415│1.572774│1.580977│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.4 │ 0.18 │1.589376│74.53905│1.586709│1.594616│
└─────┴──────┴────┴────┴┴────┴────┘
.

  Now, an electronic apparatus provided with the variable power optical system and the imaging optical system of the present invention as described above will be described. In this electronic apparatus, an imaging device is used that forms an object image with the optical system and receives the image with an imaging element such as a CCD to take an image. Electronic devices include a digital camera, a video camera, a digital video unit, a personal computer which is an example of an information processing device, a mobile computer, a telephone, a mobile phone particularly useful for carrying, and an information portable terminal. The embodiment is illustrated below.

  18 to 20 are examples of a digital camera, and are conceptual diagrams of a configuration in which the variable power optical system according to the present invention is used as the photographing optical system 41. FIG. 18 is a front perspective view showing the appearance of the digital camera 40, FIG. 19 is a rear perspective view thereof, and FIG. 20 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, a viewfinder optical system 43, a shutter 45, a flash 46, a liquid crystal display monitor 47, and the like. The photographing optical system 41 is disposed on the photographing optical path 42. The finder optical system 43 is disposed on a finder optical path 44 different from the photographing optical path 42. In addition, a shutter 45 is provided on the upper portion of the camera 40. Therefore, when the photographer presses the shutter 45, photographing is performed through the photographing optical system 41, for example, the variable magnification optical system of the first embodiment. The object image formed by the photographic optical system 41 is formed on the imaging surface of the CCD 49 via the parallel plate P1 and the cover glass P2. Here, a near ultraviolet ray cut coat is applied to the parallel plate P1. Further, the parallel plate P1 may have a low-pass filter action. The object image received by the CCD 49 is displayed on the liquid crystal display monitor 47 as an electronic image via the processing means 51. The liquid crystal display monitor 47 is provided on the back of the camera. 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. For example, the recording means 52 may be a floppy disk, a memory card, an MO, or the like. As described above, the recording unit 52 may be configured to perform recording and writing electronically. Further, in place of the CCD 49, a silver salt camera having a silver salt film may be configured.

  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. Here, the field frame 57 is provided on a 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 arranged on the incident side of the photographic optical system 41 and the finder objective optical system 53 and on the exit side of the eyepiece optical system 59, respectively. Here, although a plane parallel plate is disposed as the cover member 50, a lens having power may be used.

  The digital camera 40 configured as described above can achieve high performance and downsizing since the photographing optical system 41 is high performance and small.

  Next, FIG. 21 to FIG. 23 are personal computers as an example of an information processing apparatus, and are conceptual diagrams of configurations using the variable magnification optical system of the present invention as an objective optical system. 21 is a front perspective view with the cover of the personal computer 300 opened, FIG. 22 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 23 is a side view of the state of FIG.

  The personal computer 300 includes a keyboard 301 for a writer to input information from the outside, a monitor 302 for displaying information to the operator, and a photographing optical system 303 for photographing the operator himself and surrounding images. ing. Furthermore, the personal computer 300 has information processing means and recording means not shown. 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. In the drawing, the photographing optical system 303 is built in the upper right of the monitor 302, but is not limited to that location. For example, it may be anywhere around the monitor 302 or around the keyboard 301.

  The photographing optical system 303 has an objective lens 112 made up of a variable magnification optical system (abbreviated in the drawing) according to the present invention and an image sensor chip 162 that receives an image on a photographing optical path 304. These are built in the personal computer 300.

  Here, a plane parallel plate group F such as an optical low-pass filter is additionally attached on the image sensor chip 162. Therefore, the imaging element chip 162 and the plane parallel plate group F are integrated to form the imaging unit 160. The imaging unit 160 can be fitted and attached to the rear end of the lens frame 113 of the objective lens 112 with one touch. Therefore, centering of the objective lens 112 and the image sensor chip 162 and adjustment of the surface interval are unnecessary, and assembly is simple. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113. The driving mechanism for the variable magnification optical system 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 via the terminal 166. The object image is displayed on the monitor 302 as an electronic image. FIG. 21 shows an image 305 photographed by the operator as an example. 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. 24 is a telephone which is an example of an information processing apparatus, and is a conceptual diagram of a configuration in which the variable power optical system of the present invention is used as a photographing optical system. Here, the telephone is a mobile phone that is convenient to carry. 24A is a front view of the mobile phone 400, FIG. 24B is a side view, and FIG. 24C is a cross-sectional view of the photographing optical system 405.

  The cellular phone 400 includes a microphone unit 401, a speaker unit 402, an input dial 403, a monitor 404, a photographing optical system 405, an antenna 406, and processing means (not shown). An operator's voice is input to the microphone unit 401 as information. The speaker unit 402 outputs the voice of the other party. The input dial 403 has buttons for an operator to input information. The monitor 404 displays a photographed image of the operator himself / herself and the other party, information such as a telephone number. The antenna 406 transmits and receives communication radio waves. 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 is disposed on the photographing optical path 407. The photographing optical system 405 includes an objective lens 112 including a variable magnification optical system (abbreviated in the drawing) according to the present invention, and an image sensor chip 162 that receives an object image. These are built in the mobile phone 400.

  Here, a plane parallel plate group F such as an optical low-pass filter is additionally attached on the image sensor chip 162. Therefore, the imaging element chip 162 and the plane parallel plate group F are integrated to form the imaging unit 160. The imaging unit 160 can be fitted and attached to the rear end of the lens frame 113 of the objective lens 112 with one touch. Therefore, centering of the objective lens 112 and the image sensor chip 162 and adjustment of the surface interval are unnecessary, and assembly is simple. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113. The driving mechanism for the variable magnification optical system in the lens frame 113 is not shown.

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

  The variable power optical system of the present invention and the electronic apparatus using the same can be configured as follows, for example.

[1] In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a positive refractive power A variable magnification optical system composed of a fourth lens group,
The second lens group is composed of one positive lens,
The variable power optical system characterized in that the second lens group and the third lens group satisfy the following conditional expression.

−100 <HF ₂₃ / SD ₂₃ <−0.3 (1)
However, HF ₂₃ : the front principal point position of the composition at the wide angle end of the second lens group and the third lens group (value measured from the top of the object side surface of the second lens group),
SD ₂₃ : Sum of lens thicknesses included in the second lens group and the third lens group,
It is.

    [2] The variable magnification optical system as described in 1 above, wherein at least one negative lens included in the first lens group has an aspherical surface on the object side.

    [3] The variable power optical system as described in 1 or 2 above, wherein at least one negative lens included in the first lens group has an aspherical surface on the image side surface.

    [4] The zoom optical system according to any one of 1 to 3, wherein at least one negative lens included in the first lens group is a lens made of a resin material.

    [5] The variable magnification optical system according to any one of 1 to 4, wherein the first lens group satisfies the following conditional expression.

−10 <SF _G1 <1 (2)
Where SF _G1 is the shaping factor of the first lens group,
SF _G1 = (r _G11 + r _G12 ) / (r _G11 −r _G12 )
r _G11 : radius of curvature of the most object side surface of the first lens group,
r _G12 : radius of curvature of the most image-side surface of the first lens group,
It is.

    [6] The variable magnification optical system according to any one of 1 to 5, wherein at least one negative lens included in the first lens group is made of a material that satisfies the following conditional expression: system.

40 <ν _d1 <100 (3)
Where ν _{d1 is} the Abbe number of the negative lens in the first lens group,
It is.

    [7] The variable magnification optical system according to any one of [1] to [6], wherein at least one negative lens included in the first lens group satisfies the following conditional expression:

0.5 <| f ₁ | / f _w <5 (4)
However, f _1: focal length of the negative lens in the first lens group,
f _w : the converted focal length of the entire system at the wide-angle end,
f _w = (Y _h × 0.6) / tanω
Y _h : maximum image height,
ω: half angle of view of light incident on 60% of maximum image height,
It is.

    [8] The variable magnification optical system according to any one of 1 to 7, wherein the first lens group includes at least one positive lens.

    [9] The variable magnification optical system as described in 8 above, wherein the positive lens is disposed closest to the image side.

    [10] The variable magnification optical system according to any one of [1] to [9], wherein the positive lens of the second lens group is made of a material that satisfies the following conditional expression.

−30 × 10 ⁻⁶ <dn ₂ / dT <50 × 10 ⁻⁶ (7)
Where dn ₂ / dT: temperature coefficient of refractive index at the d-line of the positive lens in the second lens group [° C. ⁻¹ ],
It is.

    [11] The variable magnification optical system according to any one of 1 to 10, wherein the positive lens of the second lens group has an aspherical surface on the object side.

    [12] The variable magnification optical system according to any one of [1] to [11], wherein the positive lens of the second lens group has an aspheric surface on the image side.

    [13] The variable magnification optical system according to any one of 1 to 12, wherein the second lens group satisfies the following conditional expression.

−5 <SF ₂ <1 (6)
Where SF ₂ is the shaping factor of the positive lens in the second lens group,
SF ₂ = (r ₂₁ + r ₂₂ ) / (r ₂₁ −r ₂₂ )
r ₂₁ : radius of curvature of the object side surface of the positive lens in the second lens group,
r ₂₂ : radius of curvature of the image side surface of the positive lens in the second lens group,
It is.

    [14] The zoom lens system according to any one of [1] to [13], wherein the positive lens of the second lens group is made of a material that satisfies the following conditional expression.

35 <ν _d2 <100 (7)
Where ν _{d2 is} the Abbe number of the positive lens in the second lens group,
It is.

    [15] The zoom lens system according to any one of [1] to [14], wherein the positive lens of the second lens group satisfies the following conditional expression:

0.3 <| f ₂ | / f _w <1.3 (8)
Where f _{2 is} the focal length of the positive lens in the second lens group,
f _w : the converted focal length of the entire system at the wide-angle end,
f _w = (Y _h × 0.6) / tanω
Y _h : maximum image height,
ω: half angle of view of light incident on 60% of maximum image height,
It is.

    [16] The positive lens of the second lens group is made of a material having a higher refractive index than any of the other lenses included in the first lens group and the third lens group. The zoom optical system according to any one of the preceding claims.

    [17] The variable magnification optical system according to any one of [1] to [16], wherein at least one negative lens of the third lens group is a lens made of a resin material.

    [18] The zoom optical system according to any one of 1 to 17, wherein at least one negative lens of the third lens group satisfies the following conditional expression:

−1 <SF ₃ <10 (9)
Where SF ₃ is the shaping factor of the negative lens of the third lens group,
SF ₂ = (r ₃₁ + r ₃₂ ) / (r ₃₁ −r ₃₂ )
r ₃₁ : radius of curvature of the object side surface of the negative lens of the third lens group,
r ₃₂ : radius of curvature of the image side surface of the negative lens of the third lens group,
It is.

    [19] The zoom optical system according to any one of 1 to 18, wherein at least one negative lens of the third lens group is made of a material that satisfies the following conditional expression.

0 <ν _d3 <45 (10)
Where ν _{d3 is} the Abbe number of the negative lens in the third lens group,
It is.

    [20] The variable magnification optical system according to any one of [1] to [19], wherein at least one positive lens of the fourth lens group is made of a resin material.

    [21] The variable magnification optical system according to any one of [1] to [20], wherein at least one positive lens in the fourth lens group satisfies the following conditional expression:

-1 <SF ₄ <10 (11)
Where SF ₄ is the shaping factor of the positive lens in the fourth lens group,
SF ₄ = (r ₄₁ + r ₄₂ ) / (r ₄₁ −r ₄₂ )
r _41: the curvature of the object side surface of the positive lens in the fourth lens group,
r ₄₂ : radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.

    [22] The variable magnification optical system according to any one of [1] to [21], wherein at least one positive lens in the fourth lens group is made of a material that satisfies the following conditional expression.

40 <ν _d4 <100 (12)
Where ν _{d4 is} the Abbe number of the positive lens in the fourth lens group,
It is.

    [23] The zoom optical system according to any one of [1] to [22], wherein the position of the first lens group in the optical axis direction is fixed during zooming.

    [24] The zoom optical system according to any one of [1] to [23], wherein an interval between the second lens group and the third lens group is constant during zooming.

    [25] The variable magnification optical system as described in any one of 1 to 24 above, wherein the following conditional expression is satisfied.

−35 <DT _min <20 (13)
However, DT _min : Distortion amount [%],
It is.

    [26] The variable power optical system as set forth in any one of [1] to [25], wherein distortion aberration generated in the optical system is electrically corrected.

    [27] The variable power optical system as set forth in any one of [1] to [26], wherein chromatic aberration of magnification generated in the optical system is electrically corrected.

    [28] The variable power optical system as described in any one of 1 to 27 above, wherein an organic-inorganic composite material is used as an optical material of at least one optical element constituting the optical system.

    [29] The variable power optical system as described in 28 above, wherein the organic-inorganic composite includes zirconia nanoparticles.

    [30] The variable power optical system as described in 28 above, wherein the organic-inorganic composite includes nanoparticles of zirconia and alumina.

    [31] The variable magnification optical system as set forth in [28], wherein the organic-inorganic composite includes niobium oxide nanoparticles.

    [32] The variable power optical system as set forth in [28], wherein the organic-inorganic composite includes a hydrolyzate of zirconium alkoxide and alumina nanoparticles.

    [33] An electronic apparatus comprising: the variable magnification optical system according to any one of 1 to 32 above; and an electronic imaging device disposed on the image side thereof.

FIG. 3 is a lens cross-sectional view at a wide angle end (a), an intermediate state (b), and a telephoto end (c) when focusing on an object point at infinity according to Example 1 of the variable magnification optical system of the present invention. FIG. 3 is a lens cross-sectional view similar to FIG. 1 of the variable magnification optical system of Example 2. FIG. 4 is a lens cross-sectional view similar to FIG. 1 of the variable magnification optical system of Example 3. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of the variable magnification optical system of Example 4. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of the variable magnification optical system of Example 5. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of the variable magnification optical system of Example 6. FIG. 10 is a lens cross-sectional view similar to FIG. 1 of the variable magnification optical system of Example 7. 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. 9 is an aberration diagram similar to FIG. 8 of Example 2. FIG. 13 is an aberration diagram similar to FIG. 12 of Example 3. FIG. 9 is an aberration diagram similar to FIG. 8 of Example 4. FIG. 9 is an aberration diagram similar to FIG. 8 of Example 5. FIG. 10 is an aberration diagram similar to FIG. 8 of Example 6. FIG. 10 is an aberration diagram similar to FIG. 8 of Example 7. It is an aberration diagram showing an example of the distortion aberration amount DT _min . It is an optical distortion figure which shows the barrel distortion as an example of an optical distortion, and the image of an original screen. It is a block block diagram of an example of the image processing apparatus which performs optical distortion correction. It is a front perspective view which shows the external appearance of the digital camera incorporating the variable magnification optical system by this invention. FIG. 19 is a rear perspective view of the digital camera of FIG. 18. It is sectional drawing of the digital camera of FIG. It is the front perspective view which opened the cover of the personal computer incorporating the variable magnification optical system by this invention 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. FIG. 2 is a front view (a), a side view (b), and a sectional view (c) of the photographing optical system of a mobile phone in which the variable magnification optical system according to the present invention is incorporated as an objective optical system.

Explanation of symbols

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group G4 ... 4th lens group S ... Aperture stop F ... Parallel plane plate group I ... Image plane E ... Observer eyeball 1 ... Zoom lens 2 ... CCD
3 ... Imaging process circuit 4 ... A / D conversion circuit 5 ... Image memory 6 ... Interpolation processing circuit 7 ... D / A converter 8 ... TG (timing generation) circuit 9 ... SSG (synchronization signal generation) circuit 10 ... Write control circuit 12A ... Read control circuit 13A ... Correction amount ROM
40 ... Digital camera 41 ... Shooting optical system 42 ... Shooting optical path 43 ... Viewfinder optical system 44 ... Viewfinder optical path 45 ... Shutter 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 ... Porro prism 57 ... Field frame 59 ... Eyepiece optical system 101 ... Screen 102 without distortion ... Screen 112 with optical distortion ... Objective lens 113 ... Mirror frame 114 ... Cover glass 160 ... Imaging unit 162 ... Imaging element chip 166 ... Terminal 300 ... PC 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 ... photographing optical system 406 ... antenna 407 ... photographing optical path

Claims (3)

In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power A variable magnification optical system composed of a group,
The second lens group is composed of one positive lens,
The variable power optical system characterized in that the second lens group and the third lens group satisfy the following conditional expression.
−100 <HF ₂₃ / SD ₂₃ <−0.3 (1)
However, HF ₂₃ : the front principal point position of the composition at the wide angle end of the second lens group and the third lens group (value measured from the top of the object side surface of the second lens group),
SD ₂₃ : Sum of lens thicknesses included in the second lens group and the third lens group,
It is. The variable magnification optical system according to claim 1, wherein the first lens group satisfies the following conditional expression.
−10 <SF _G1 <1 (2)
Where SF _G1 is the shaping factor of the first lens group,
SF _G1 = (r _G11 + r _G12 ) / (r _G11 −r _G12 )
r _G11 : radius of curvature of the most object side surface of the first lens group,
r _G12 : radius of curvature of the most image-side surface of the first lens group,
It is. 3. An electronic apparatus comprising: the variable magnification optical system according to claim 1; and an electronic image pickup device disposed on an image side thereof.

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