Variable magnification optical system and imaging apparatus

Abstract

To provide a variable magnification optical system that is small-sized, can increase the aperture ratio and variable magnification of the variable magnification optical system, and has suitably corrected aberrations.SOLUTION: A variable magnification optical system has, in order from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, a positive fourth lens group G4, and a negative fifth lens group G5. In variation of magnification from a wide-angle end to a telephoto end, the interval between the first lens group and the second lens group, the interval between the second lens group and the third lens group, and the interval between the third lens group and the fourth lens group change. In focusing from an infinite end to a closest end, either one of the fourth lens group or the fifth lens group moves along an optical axis. The third lens group has at least one negative lens. An object-side lens surface of a negative lens L3n, which is arranged on the most image side in the third lens group, is convex to the image side. The fourth lens group has at least one negative lens. An object-side lens surface of a negative lens L4n, which is arranged on the most object side in the fourth lens group, is convex to the image side. The variable magnification optical system satisfies specific conditional expressions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a variable magnification optical system and an imaging device. [Background technology]

[0002] 2. Description of the Related Art There are market demands for variable magnification optical systems used in image pickup apparatuses that are small in size, have a large aperture ratio, a high variable magnification ratio, and have various aberrations well corrected.

[0003] Conventionally, variable magnification optical systems have been proposed that are compact yet compatible with large image sensors, and that provide excellent correction of various aberrations from the wide-angle end to the telephoto end (for example, Patent Document 1). Also, compact variable magnification optical systems that have a high variable magnification ratio, a wide angle of view, and excellent optical performance, and optical devices incorporating such variable magnification optical systems, have been proposed (for example, Patent Document 2). Furthermore, variable magnification optical systems that are compact overall despite having a large aperture ratio and excellent optical performance, and imaging devices incorporating such variable magnification optical systems, have been proposed (for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2019 / 049370 publication [Patent Document 2] Japanese Patent Application Publication No. 2020-071439 [Patent Document 3] Japanese Patent Publication No. 2023-004721 [Non-patent literature]

[0005] [Non-Patent Document 1] Yoshiya Matsui, "Lens Design Method", Kyoritsu Publishing, November 5, 1972, pp. 77-128 [Non-patent document 2] Yoshiya Matsui, "Normalization of Aberration Coefficients for New Optical Systems," Optics, Optical Society of Japan, October 1994, Vol. 23, No. 10, pp. 634-640 [Non-patent document 3] Hiroshi Inoue, "Inspection Techniques for Optical Elements and Mechanisms, Revised Edition II, Mechanism Parts Edition," Optronics Co., Ltd., April 10, 2009, pp. 95-96 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned background art, it has been difficult to provide a variable magnification optical system that is sufficiently compact, has a large aperture ratio, and a high zoom ratio, and in which various aberrations are well corrected. For example, it is difficult to achieve a large aperture ratio in the variable magnification optical system described in Patent Document 2, and it is difficult to achieve a high zoom ratio in the variable magnification optical systems described in Patent Documents 1 and 3.

[0007] The present invention provides a variable magnification optical system for use in an image pickup apparatus that is compact, has a large aperture ratio and a high variable magnification ratio, and has various aberrations well corrected. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a zoom lens having, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power, wherein, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the third lens group G3 changes, and the distance between the third lens group G3 and the fourth lens group G4 changes, and when zooming from the infinity end to the closest distance end, a variable magnification optical system characterized in that, when the variable magnification optical system is in a state in which either the fourth lens group G4 or the fifth lens group G5 moves along the optical axis, the third lens group G3 has at least one negative lens, the object-side lens surface of the negative lens L3n arranged closest to the image in the third lens group G3 is convex toward the image side, the fourth lens group G4 has at least one negative lens, the object-side lens surface of the negative lens L4n arranged closest to the object in the fourth lens group G4 is convex toward the image side, and the following conditional expression is satisfied: (1) 0.61 <f34 / fW<1.46 (2) 0.32 <f4 / f3<0.96 (3)-0.0085<ΔPgF1+ΔPgF2<0.0070 f34: the composite focal length of the third lens group G3 to the fourth lens group G4, where f34=1 / (Σ(1 / fn)), n=3 to 4, and fn is the focal length of the n-th lens group. fW: focal length at the wide-angle end of the variable magnification optical system f4: the focal length of the fourth lens group G4 f3: focal length of the third lens group G3 ΔPgF1: anomalous dispersion of the negative lens L3n located closest to the image in the third lens group G3, where ΔPgF1=PgF1-0.64833+0.00180×νd1. PgF1 is the partial dispersion ratio for the g-line and F-line of the negative lens L3n located closest to the image in the third lens group G3. νd1 is the Abbe number for the d-line of the negative lens L3n located closest to the image in the third lens group G3. ΔPgF2: anomalous dispersion of the negative lens L4n located closest to the object in the fourth lens group G4, where ΔPgF2=PgF2-0.64833+0.00180×νd2. PgF2 is the partial dispersion ratio for the g-line and F-line of the negative lens L4n located closest to the object in the fourth lens group G4. νd2 is the Abbe number for the d-line of the negative lens L4n located closest to the object in the fourth lens group G4. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a variable magnification optical system for use in an imaging device that is compact, has a large aperture ratio and a high variable magnification ratio, and has various aberrations well corrected. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of the first embodiment when focusing on an object at infinity at the wide-angle end. [Figure 2]2A, 2B, and 2C are longitudinal aberration diagrams according to Example 1 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 3] 3A, 3B, and 3C are lateral aberration diagrams according to Example 1 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 4] FIG. 4 is a cross-sectional view of the second embodiment when focused on an object at infinity at the wide-angle end. [Figure 5] 5A, 5B, and 5C are longitudinal aberration diagrams according to Example 2 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 6] 6A, 6B, and 6C are lateral aberration diagrams according to Example 2 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 7] FIG. 7 is a cross-sectional view of Example 3 when focusing on an object at infinity at the wide-angle end. [Figure 8] 8A, 8B, and 8C are longitudinal aberration diagrams according to Example 3 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 9] 9A, 9B, and 9C are lateral aberration diagrams according to Example 3 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 10] FIG. 10 is a cross-sectional view of Example 4 when focusing on an object at infinity at the wide-angle end. [Figure 11] 11A, 11B, and 11C are longitudinal aberration diagrams according to Example 4 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 12] 12A, 12B, and 12C are lateral aberration diagrams when an object at infinity is in focus at the wide-angle end, the intermediate focal length, and the telephoto end according to Example 4, respectively. [Figure 13] FIG. 13 is a cross-sectional view of Example 5 when focusing on an object at infinity at the wide-angle end. [Figure 14]14A, 14B, and 14C are longitudinal aberration diagrams according to Example 5 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 15] 15A, 15B, and 15C are lateral aberration diagrams when an object at infinity is in focus at the wide-angle end, the intermediate focal length, and the telephoto end according to Example 5, respectively. [Figure 16] FIG. 16 is a cross-sectional view of Example 6 when focusing on an object at infinity at the wide-angle end. [Figure 17] 17A, 17B, and 17C are longitudinal aberration diagrams according to Example 6 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 18] 18A, 18B, and 18C are lateral aberration diagrams when an object at infinity is in focus at the wide-angle end, the intermediate focal length, and the telephoto end according to Example 6, respectively. [Figure 19] FIG. 19 is a cross-sectional view of Example 7 when focusing on an object at infinity at the wide-angle end. [Figure 20] 20A, 20B, and 20C are longitudinal aberration diagrams according to Example 7 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 21] 21A, 21B, and 21C are lateral aberration diagrams according to Example 7 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 22] FIG. 22 is a cross-sectional view of Example 8 when focusing on an object at infinity at the wide-angle end. [Figure 23] 23A, 23B, and 23C are longitudinal aberration diagrams according to Example 8 when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, respectively. [Figure 24] 24A, 24B, and 24C are lateral aberration diagrams according to Example 8 when focusing on an object at infinity at the wide-angle end, at the intermediate focal length, and at the telephoto end, respectively. [Figure 25]25A, 25B, and 25C are lateral aberration diagrams when image stabilization is performed at an image blur correction angle of 0.3° when focusing on an object at infinity at the wide-angle end, the intermediate focal length, and the telephoto end according to Example 8, respectively. [Figure 26] FIG. 26 is a diagram showing the configuration of an imaging device equipped with a variable magnification optical system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] A variable magnification optical system and an image pickup apparatus incorporating the variable magnification optical system according to the present invention will be described below. First, an embodiment of the present invention will be described.

[0012] In the present invention, when counting the number of lenses, unless otherwise specified, a single lens is counted as one lens, and in the case of a cemented lens, each of the single lenses constituting the cemented lens is counted as one lens. For example, a cemented lens consisting of a convex lens and a concave lens is counted as two lenses.

[0013] The variable magnification optical system of the present invention has, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power, and when varying magnification from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the third lens group G3 changes, and the distance between the third lens group G3 and the fourth lens group G4 changes, and when focusing from the infinity end to the closest distance end, a variable magnification optical system wherein either the fourth lens group G4 or the fifth lens group G5 moves along an optical axis, the third lens group G3 has at least one negative lens, the object-side lens surface of the negative lens L3n arranged closest to the image in the third lens group G3 is convex toward the image side, the fourth lens group G4 has at least one negative lens, the object-side lens surface of the negative lens L4n arranged closest to the object in the fourth lens group G4 is convex toward the image side, and the following conditional expression is satisfied: (1) 0.61 <f34 / fW<1.46 (2) 0.32 <f4 / f3<0.96 (3)-0.0085<ΔPgF1+ΔPgF2<0.0070 f34: the composite focal length of the third lens group G3 to the fourth lens group G4, where f34=1 / (Σ(1 / fn)), n=3 to 4, and fn is the focal length of the n-th lens group. fW: focal length at the wide-angle end of the variable magnification optical system f4: the focal length of the fourth lens group G4 f3: focal length of the third lens group G3 ΔPgF1: anomalous dispersion of the negative lens L3n located closest to the image in the third lens group G3, where ΔPgF1=PgF1-0.64833+0.00180×νd1. PgF1 is the partial dispersion ratio for the g-line and F-line of the negative lens L3n located closest to the image in the third lens group G3. νd1 is the Abbe number for the d-line of the negative lens L3n located closest to the image in the third lens group G3. ΔPgF2: anomalous dispersion of the negative lens L4n located closest to the object in the fourth lens group G4, where ΔPgF2=PgF2-0.64833+0.00180×νd2. PgF2 is the partial dispersion ratio for the g-line and F-line of the negative lens L4n located closest to the object in the fourth lens group G4. νd2 is the Abbe number for the d-line of the negative lens L4n located closest to the object in the fourth lens group G4.

[0014] The configuration of the present invention aims to achieve a compact, variable-magnification optical system with a large aperture ratio and a high zoom ratio, and to effectively correct various aberrations. By providing the first lens group G1 with positive refractive power and the fifth lens group G5 with negative refractive power, it becomes easier to position the rear principal point of the variable-magnification optical system toward the object side, allowing for a compact variable-magnification optical system. Furthermore, by providing the second lens group G2 with negative refractive power, it becomes easier to suppress changes in the lateral magnification of the lens group located closer to the image than the second lens group G2 when zooming from the wide-angle end to the telephoto end, allowing for a high zoom ratio of the variable-magnification optical system.

[0015] Next, by providing the third lens group G3 and the fourth lens group G4 with positive refractive power, it becomes easier to suppress changes in the focal position that occur when changing magnification from the wide-angle end to the telephoto end, and further, it becomes unnecessary to forcibly increase the refractive power of the third lens group G3 or the fourth lens group G4, which means that aberration correction in the third lens group G3 and the fourth lens group G4 becomes easier, and it becomes possible to achieve a large aperture ratio for the variable magnification optical system. Also, by making the object-side lens surface of the negative lens located closest to the image in the third lens group G3 face convexly toward the image side, and by making the object-side lens surface of the negative lens located closest to the object in the fourth lens group G4 face convexly toward the image side, it becomes possible to efficiently suppress spherical aberration and axial chromatic aberration that may occur in the third lens group G3 and the fourth lens group G4, and it becomes possible to achieve a high variable magnification ratio and a large aperture ratio for the variable magnification optical system.

[0016] Conditional formula (1) is a conditional formula for prescribing an appropriate value for the ratio between the combined focal length of the third lens group G3 and the fourth lens group G4 and the focal length at the wide-angle end of the variable magnification optical system, and is related to achieving a large aperture ratio of the variable magnification optical system.

[0017] If the upper limit of conditional expression (1) is exceeded and the refractive power of the third to fourth lens groups G3 to G4 becomes weak, the ability to correct off-axis aberrations of the lens groups located closer to the image than the fourth lens group G4 decreases, making it difficult to correct astigmatism, particularly at the telephoto end.If the lower limit of conditional expression (1) is exceeded and the refractive power of the third to fourth lens groups G3 to G4 becomes strong, the ability to correct on-axis aberrations of those lens groups decreases, making it difficult to correct spherical aberration, particularly at the wide-angle end to the telephoto end.

[0018] In order to ensure the effects of the present invention, it is preferable that the upper limit of conditional expression (1) be set to 1.32 and the lower limit to 0.67, and it is even more preferable that the upper limit be set to 1.19 and the lower limit to 0.74.

[0019] Conditional expression (2) is a conditional expression for defining an appropriate value for the ratio between the focal length of the fourth lens group G4 and the focal length of the third lens group G3, and is related to achieving a high zoom ratio in the variable-magnification optical system.

[0020] If the refractive power of the third lens group G3 becomes too strong, exceeding the upper limit of conditional expression (2), correction of on-axis aberrations within that lens group will result in worsening off-axis aberrations, making it particularly difficult to correct coma at the telephoto end.If the refractive power of the fourth lens group G4 becomes too strong, exceeding the lower limit of conditional expression (2), correction of on-axis aberrations within that lens group will result in worsening off-axis aberrations, making it particularly difficult to correct astigmatism at the wide-angle end.

[0021] In order to ensure the effects of the present invention, it is preferable that the upper limit of conditional expression (2) be set to 0.91 and the lower limit to 0.34, and it is even more preferable that the upper limit be set to 0.87 and the lower limit to 0.35.

[0022] Conditional expression (3) is a conditional expression for defining an appropriate value for the sum of the chromatic aberration correction capabilities of the third lens group G3 and the fourth lens group G4, and is related to achieving a high zoom ratio in the variable-magnification optical system.

[0023] If the upper limit of conditional expression (3) is exceeded and the sum of the anomalous dispersion of the negative lens L3n located closest to the image in the third lens group G3 and the anomalous dispersion of the negative lens L4n located closest to the object in the fourth lens group G4 becomes large, the behavior of light rays passing through the third lens group G3 to the fourth lens group G4 becomes excessive on the short wavelength side, making it difficult to correct axial chromatic aberration, particularly at the telephoto end.If the lower limit of conditional expression (3) is exceeded and the sum of the anomalous dispersion of the negative lens L3n located closest to the image in the third lens group G3 and the anomalous dispersion of the negative lens L4n located closest to the object in the fourth lens group G4 becomes small, the behavior of light rays passing through the third lens group G3 to the fourth lens group G4 becomes insufficient on the short wavelength side, making it difficult to correct axial chromatic aberration, particularly at the wide-angle end.

[0024] In order to ensure the effects of the present invention, it is preferable to set the upper limit of conditional expression (3) to 0.0069 and the lower limit to −0.0084, and it is even more preferable to set the upper limit to 0.0068 and the lower limit to −0.0083.

[0025] Furthermore, the variable magnification optical system of the present invention is characterized in that it satisfies the following conditional expression: (4) 0.13<|f13| / f4L<1.25 f13: a composite focal length of the first lens group G1 to the third lens group G3, where f13=1 / (Σ(1 / fn)), n=1 to 3, and fn is the focal length of the n-th lens group. f4L: composite focal length of the fourth lens group G4 through the lens group arranged closest to the image (hereinafter referred to as the final lens group GL), where f4L=1 / (Σ(1 / fn)), n=4 to L, fn is the focal length of the nth lens group, and fL is the focal length of the final lens group.

[0026] Conditional expression (4) is a conditional expression for prescribing an appropriate value for the ratio between the composite focal length of the first lens group G1 to the third lens group G3 and the composite focal length of the fourth lens group G4 to the lens group arranged closest to the image (hereinafter referred to as the final lens group GL), and is related to shortening the overall length of the variable magnification optical system.

[0027] If the refractive power of the fourth to final lens groups GL becomes too strong beyond the upper limit of conditional expression (4), the ability to correct off-axis aberrations in the fourth to final lens groups G4 to GL decreases, making it difficult to correct coma aberrations, particularly at the telephoto end.If the refractive power of the first to third lens groups G1 to G3 becomes too strong beyond the lower limit of conditional expression (4), the ability to correct off-axis aberrations in the first to third lens groups G1 to G3 decreases, making it difficult to correct astigmatism, particularly at the wide-angle end.

[0028] In order to ensure the effects of the present invention, it is preferable to set the upper limit of conditional expression (4) to 0.95 and the lower limit to 0.16, and it is even more preferable to set the upper limit to 0.78 and the lower limit to 0.20.

[0029] Furthermore, the variable magnification optical system of the present invention is characterized in that it satisfies the following conditional expression: (5) 1.12 <m4 / m3<1.56 m4: the amount of movement of the fourth lens group G4 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive) m3: the amount of movement of the third lens group G3 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive)

[0030] Conditional expression (5) is a conditional expression for prescribing an appropriate value for the ratio between the total amount of movement of the fourth lens group G4 during magnification change and the total amount of movement of the third lens group G3 during magnification change, and is related to the aberration correction ability of the variable magnification optical system.

[0031] If the upper limit of conditional expression (5) is exceeded and the distance between the third lens group G3 and the fourth lens group G4 at the wide-angle end becomes large, the height of the off-axial chief ray incident on the fourth lens group G4 at the wide-angle end becomes excessively high, making it difficult to correct astigmatism, particularly at the wide-angle end.If the lower limit of conditional expression (5) is exceeded and the distance between the third lens group G3 and the fourth lens group G4 at the wide-angle end becomes small, the height of the off-axial chief ray incident on the fourth lens group G4 at the wide-angle end becomes excessively low, making it difficult to correct astigmatism, particularly at the wide-angle end.

[0032] In order to ensure the effects of the present invention, it is preferable that the upper limit of conditional expression (5) be set to 1.53 and the lower limit to 1.14, and it is even more preferable that the upper limit be set to 1.50 and the lower limit to 1.16.

[0033] Furthermore, the variable magnification optical system of the present invention is characterized in that it satisfies the following conditional expression: (6) 1.17<|f5| / f4<2.89 f5: focal length of the fifth lens group G5 f4: the focal length of the fourth lens group G4

[0034] Conditional expression (6) is a conditional expression for defining an appropriate value for the ratio between the focal length of the fifth lens group G5 and the focal length of the fourth lens group G4, and is related to the aberration correction ability of the variable magnification optical system.

[0035] If the refractive power of the fourth lens group G4 becomes too strong, exceeding the upper limit of conditional expression (6), correction of on-axis aberrations in that lens group will result in worsening off-axis aberrations, making it particularly difficult to correct coma at the telephoto end.If the refractive power of the fifth lens group G5 becomes too strong, exceeding the lower limit of conditional expression (6), correction of on-axis aberrations in that lens group will result in worsening off-axis aberrations, making it particularly difficult to correct coma at the wide-angle end.

[0036] In order to ensure the effects of the present invention, it is preferable that the upper limit of conditional expression (6) be set to 2.75 and the lower limit to 1.23, and it is even more preferable that the upper limit be set to 2.61 and the lower limit to 1.29.

[0037] Furthermore, the variable magnification optical system of the present invention is characterized in that it satisfies the following conditional expression: (7) 0.83 <m5 / m4<1.24 m5: the amount of movement of the fifth lens group G5 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive) m4: the amount of movement of the fourth lens group G4 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive)

[0038] Conditional expression (7) is a conditional expression for prescribing an appropriate value for the ratio between the total amount of movement of the fifth lens group G5 during magnification change and the total amount of movement of the fourth lens group G4 during magnification change, and is related to the aberration correction ability of the variable magnification optical system.

[0039] If the distance between the fourth lens group G4 and the fifth lens group G5 at the wide-angle end is increased beyond the upper limit of conditional expression (7), the burden of off-axis aberration correction by the fifth lens group G5 at the wide-angle end increases, making it particularly difficult to correct coma aberration at the wide-angle end.If the distance between the fourth lens group G4 and the fifth lens group G5 at the telephoto end is increased beyond the lower limit of conditional expression (7), the burden of off-axis aberration correction by the fifth lens group G5 at the telephoto end increases, making it particularly difficult to correct coma aberration at the telephoto end.

[0040] In order to ensure the effects of the present invention, it is preferable to set the upper limit of conditional expression (7) to 1.22 and the lower limit to 0.84, and it is even more preferable to set the upper limit to 1.19 and the lower limit to 0.86.

[0041] Furthermore, the variable magnification optical system of the present invention is characterized in that it satisfies the following conditional expression: (8) 1.34<|f5L| / fW<4.25 f5L: composite focal length of the fifth lens group G5 to the final lens group GL, where f5L=1 / (Σ(1 / fn)), n=5 to L, fn is the focal length of the nth lens group, and fL is the focal length of the final lens group GL. fW: focal length at the wide-angle end of the variable magnification optical system

[0042] Conditional expression (8) is a conditional expression for prescribing an appropriate value for the ratio between the combined focal length of the fifth lens group G5 through the final lens group GL and the focal length at the wide-angle end of the variable magnification optical system, and is related to the aberration correction ability of the variable magnification optical system.

[0043] When the upper limit of conditional expression (8) is exceeded and the refractive power of the fifth lens group G5 to the final lens group GL becomes weak, the ability of the final lens group GL to correct on-axis aberrations decreases, making it difficult to correct spherical aberrations, particularly at the telephoto end.When the lower limit of conditional expression (8) is exceeded and the refractive power of the fifth lens group G5 to the final lens group GL becomes strong, the ability of the final lens group GL to correct off-axis aberrations decreases, making it difficult to correct astigmatism, particularly at the wide-angle end.

[0044] In order to ensure the effects of the present invention, it is preferable that the upper limit of conditional expression (8) be set to 3.84 and the lower limit to 1.49, and it is even more preferable that the upper limit be set to 3.46 and the lower limit to 1.65.

[0045] Furthermore, the variable magnification optical system of the present invention is characterized in that it satisfies the following conditional expression: (9) 0.51 <bfW / fW<1.85 bfW: back focus at the wide-angle end of the variable magnification optical system fW: focal length at the wide-angle end of the variable magnification optical system

[0046] Conditional expression (9) is a conditional expression for defining an appropriate value for the ratio between the back focal length at the wide-angle end and the focal length of the variable magnification optical system at the wide-angle end, and is related to the aberration correction ability of the variable magnification optical system.

[0047] If the distance between the final lens group GL and the image plane becomes large enough to exceed the upper limit of conditional expression (9), the final lens group GL's ability to correct off-axis aberrations will decrease, making it difficult to correct astigmatism, particularly at the wide-angle end to the telephoto end.If the distance between the final lens group GL and the image plane becomes small enough to exceed the lower limit of conditional expression (9), the final lens group GL's ability to correct on-axis aberrations will decrease, making it difficult to correct spherical aberration, particularly at the wide-angle end to the telephoto end.

[0048] In order to ensure the effects of the present invention, it is preferable to set the upper limit of conditional expression (9) to 1.76 and the lower limit to 0.53, and it is even more preferable to set the upper limit to 1.68 and the lower limit to 0.56.

[0049] Furthermore, the variable magnification optical system of the present invention is characterized in that it satisfies the following conditional expression: (10) 28.56<ωW<44.11 ωW: half angle of view at the wide-angle end of the variable magnification optical system, where ωW=arctan(Y / fW) / 2, Y is the maximum image height at the wide-angle end of the variable magnification optical system, and fW is the focal length at the wide-angle end of the variable magnification optical system.

[0050] Condition (10) is a condition for defining an appropriate value for the half angle of view at the wide-angle end, and is related to the aberration correction capability of the variable magnification optical system.

[0051] If the upper limit of conditional expression (10) is exceeded and the half angle of view at the wide-angle end becomes large, the burden of off-axis aberration correction borne by the first lens group G1 to the second lens group G2 and the fifth lens group G5 to the final lens group GL increases, making it particularly difficult to correct astigmatism at the wide-angle end to the telephoto end.If the lower limit of conditional expression (10) is exceeded and the half angle of view at the wide-angle end becomes small, the burden of on-axial aberration correction borne by the second lens group G2 to the fourth lens group G4 increases, making it particularly difficult to correct spherical aberration at the wide-angle end to the telephoto end.

[0052] In order to ensure the effects of the present invention, it is preferable that the upper limit of conditional expression (10) be set to 43.38 and the lower limit to 29.15, and it is even more preferable that the upper limit be set to 42.65 and the lower limit to 29.74.

[0053] The variable magnification optical system of the present invention discloses a configuration in which the fourth lens group G4 or the fifth lens group G5 is moved along the optical axis when focusing from the infinity end to the closest distance end, thereby achieving both a compact variable magnification optical system and excellent correction of various aberrations in the variable magnification optical system. When the fourth lens group G4 is moved during focusing, fluctuations in the off-axial ray deviation angle of the fourth lens group G4 related to focusing can be easily suppressed, making it easier to correct astigmatism, particularly at the wide-angle end. When the fifth lens group G5 is moved during focusing, fluctuations in the on-axial ray deviation angle of the fifth lens group G5 related to focusing can be easily suppressed, making it easier to correct spherical aberration, particularly at the telephoto end.

[0054] In the variable magnification optical system of the present invention, the object-side lens surface of the negative lens L3n, which is located closest to the image in the third lens group G3, is configured to be in contact with air. This makes it easier to create a difference in refractive index before and after this surface, and facilitates correction of spherical aberration and axial chromatic aberration that occur within the third lens group G3.

[0055] In the variable magnification optical system of the present invention, the object-side lens surface of the negative lens L4n, which is located closest to the object in the fourth lens group G4, is configured to be in contact with air. This makes it easier to create a difference in refractive index before and after that surface, and facilitates correction of spherical aberration and axial chromatic aberration that occur within the fourth lens group G4.

[0056] In the variable magnification optical system of the present invention, the first lens group G1 has at least one negative lens, which can suppress the occurrence of chromatic aberration caused by the first lens group G1 and facilitate correction of lateral chromatic aberration, particularly at the telephoto end.

[0057] The variable magnification optical system of the present invention has an aperture stop S located closest to the object side of the third lens group G3, and the third lens group G3 and the aperture stop S move together during magnification variation. This makes it easier to move the entrance pupil position of the variable magnification optical system closer to the object side, reduces the burden of off-axis aberration correction for the first lens group G1 and the second lens group G2, and makes it easier to correct astigmatism, particularly at the wide-angle end.

[0058] In the variable magnification optical system of the present invention, the fifth lens group G5 has at least one positive lens, which makes it possible to suppress the occurrence of chromatic aberration caused by the fifth lens group G5, and in particular makes it easy to suppress fluctuations in axial chromatic aberration during focusing at the wide-angle end to the telephoto end.

[0059] The variable magnification optical system of the present invention discloses a configuration in which the second lens group G2 is fixed relative to the image plane when changing magnification from the wide-angle end to the telephoto end. This makes it possible to maintain a balance between the change in lateral magnification caused by the second lens group G2 and the change in lateral magnification caused by the lens group located closer to the image than the second lens group G2 when changing magnification, making it easier to correct spherical aberration, particularly from the wide-angle end to the telephoto end.

[0060] The variable magnification optical system of the present invention is configured so that the final lens group GL remains stationary relative to the image plane when zooming from the wide-angle end to the telephoto end. This allows linearity to be imparted to the change in the burden of off-axis aberration correction borne by the final lens group GL that occurs when zooming, making it easier to correct astigmatism, particularly in the intermediate range.

[0061] In the variable magnification optical system of the present invention, the third lens group G3 has a vibration-reduction lens group with positive refractive power that is movable in a direction approximately perpendicular to the optical axis. Image blur can be corrected by moving the vibration-reduction lens group in a direction approximately perpendicular to the optical axis, which reduces the burden of correcting various aberrations that the vibration-reduction lens group bears when vibration-reduction is not in effect. In particular, by matching the refractive power sign of the vibration-reduction lens group with the refractive power sign of the third lens group G3, the vibration-reduction lens group can be positioned without interfering with the burden of variable magnification of the third lens group G3 as a whole, making it easier to achieve aberration correction both when vibration-reduction is in effect and when vibration-reduction is not in effect.

[0062] The imaging device of the present invention is configured to include the variable magnification optical system described above, thereby providing an imaging device that is compact, has a large aperture ratio and a high variable magnification ratio, and is equipped with a variable magnification optical system in which various aberrations are well corrected.

[0063] Next, the configuration of an embodiment of a variable magnification optical system according to the present invention will be described. In the following description, the lens configuration will be described in order from the object side to the image side.

[0064] In the [Surface Data], the surface number is the number of the lens surface or aperture stop S counted from the object side, r is the radius of curvature of each surface, d is the vertex spacing of each surface, nd is the refractive index for the d-line (wavelength 587.56 nm), vd is the Abbe number for the d-line, and PgF is the partial dispersion ratio for the g-line (wavelength 435.8 nm) and F-line (wavelength 486.1 nm).

[0065] An asterisk (*) next to a surface number indicates that the lens surface is aspherical, and BF represents the back focal length.

[0066] The (stop) attached to the surface number indicates that the aperture stop S is located at that position. The radius of curvature for the plane or aperture stop S is marked as ∞ (infinity).

[0067] [Aspherical Data] shows the coefficient values ​​that give the aspherical shape of lens surfaces marked with an * in [Surface Data]. The aspherical shape is expressed by the following equation, where y is the displacement from the optical axis in a direction perpendicular to the optical axis, z is the displacement (sag) from the intersection of the aspherical surface and the optical axis in the direction of the optical axis, r is the radius of curvature of the reference sphere, K is the Conic coefficient, and A4, A6, …, and A20 are the aspherical coefficients of order 20, respectively. z=(y^2 / r) / [1+{1-(1+K)×(y / r)^2}]+Σ(An×y^n), n=4,6,...,20

[0068] [Various Data] shows values ​​such as zoom ratio and focal length for each focal length state.

[0069] [Variable Distance Data] shows the variable distance and BF values ​​for each focal length state.

[0070] [Lens Group Data] shows the surface number of each lens group closest to the object and the composite focal length of the entire group.

[0071] Furthermore, in the values ​​of all the following specifications, the focal length f, radius of curvature r, vertex spacing d, and other length units are in millimeters (mm) unless otherwise specified; however, this is not a limitation, as the optical system can achieve the same optical performance with proportional magnification and proportional reduction.

[0072] In the lens construction diagrams corresponding to the respective embodiments, the solid arrow indicates the path of the lens group when zooming from the wide-angle end to the telephoto end, the dashed arrow with a polygonal line indicates the path of the lens group when focusing from the infinity end to the close-up end, and the dashed arrow without a polygonal line indicates the path of the lens group when image blur correction is performed, S indicates the aperture stop, I indicates the image plane, and the dash-dotted line passing through the center indicates the optical axis.

[0073] In the aberration diagrams corresponding to the respective examples, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image surface and meridional image surface, respectively. [Example]

[0074] FIG. 1 is a lens configuration diagram of a variable magnification optical system according to a first embodiment of the present invention.

[0075] Example 1 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, the sixth lens group G6 corresponding to the final lens group GL.

[0076] When changing magnification from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 increases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. Note that the second lens group G2 and the sixth lens group G6 are fixed relative to the image plane I during magnification change.

[0077] During focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0078] The first lens group G1 is composed of, in order from the object side, a cemented lens of a negative meniscus lens with a convex surface facing the object side and a biconvex lens, and a positive meniscus lens with a convex surface facing the object side.

[0079] The second lens group G2 consists of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0080] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, and a negative meniscus lens L3n with its convex surface facing the image side.

[0081] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens formed by cementing a biconcave lens L4n and a biconvex lens, and a biconvex lens.

[0082] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens.

[0083] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens and a cemented lens made up of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0084] 2A, 2B, and 2C are longitudinal aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 1. Figures 3A, 3B, and 3C are lateral aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 1. It can be seen from each aberration diagram that the variable magnification optical system according to this example has excellent correction of various aberrations from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0085] The values ​​of the specifications of the variable magnification optical system according to the first embodiment of the present invention are shown below. Numerical Example 1 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 360.2963 1.8000 1.84666 23.78 0.6192 2 111.3000 7.9378 1.43700 95.10 0.5336 3 -287.9574 0.2000 4 76.2922 5.6161 1.85033 42.70 0.5646 5 256.0148 (d5) 6* 123.0252 1.2084 1.77377 47.17 0.5557 7* 23.2300 10.4000 8 -42.7806 1.0000 1.77250 49.63 0.5504 9 43.5593 6.7372 1.78880 28.43 0.6009 10 -46.5779 3.8000 11* -22.4247 1.0000 1.69350 53.18 0.5482 12* -34.9452 (d12) 13 (Aperture) ∞ 1.5000 14* 53.6920 4.9623 1.69350 53.18 0.5482 15* -167.7039 8.2650 16 -37.5017 1.0000 1.72342 37.99 0.5820 17 -65.4124 (d17) 18 69.4007 7.6084 1.49700 81.61 0.5389 19 -53.7860 1.6515 20 -255.9684 1.0000 1.73037 32.23 0.5899 21 38.9123 6.9842 1.43700 95.10 0.5336 22 -155.2762 0.1500 23* 50.6600 6.2967 1.59201 67.02 0.5358 24* -74.2726 (d24) 25 260.8960 2.4925 1.90110 27.06 0.6072 26 -118.1175 1.0000 1.69680 55.46 0.5426 27 37.0787 (d27) 28 34.9425 7.0700 1.61997 63.88 0.5426 29 -259.7850 1.9747 30 -500.0000 2.0525 1.91082 35.25 0.5822 31 20.6760 8.4087 1.68948 31.02 0.5987 32* 58.8604 (BF) Image plane ∞ [Aspherical data] 6th floor 7th floor 11th floor 12th floor 14th floor K 0.00000 -1.00000 -1.00000 0.00000 0.00000 A4 1.85091E-07 8.62972E-06 2.24402E-05 2.70163E-05 -1.27386E-06 A6 4.26604E-08 8.64590E-08 -1.47419E-07 -1.55510E-07 -5.12422E-09 A8 -2.21868E-10 -6.91508E-10 3.52063E-10 4.98439E-10 4.41803E-11 A10 6.01194E-13 6.99967E-12 1.85113E-13 -6.83300E-13 -1.61037E-13 A12 -4.78015E-16 -3.41025E-14 -1.32511E-15 -2.83775E-16 5.07015E-17 A14 -7.32009E-19 -3.35498E-17 -7.28653E-18 -1.19661E-18 -2.39015E-19 A16 -8.78114E-22 1.25237E-18 -1.96704E-20 -7.57143E-21 2.17445E-21 A18 7.22224E-24 -5.28500E-21 1.21596E-22 9.37658E-25 8.42503E-24 A20 -6.75429E-27 7.25132E-24 5.37674E-26 1.60524E-25 -1.61985E-26 15th floor 23rd floor 24th floor 32nd floor K 0.00000 0.00000 0.00000 0.00000 A4 5.74097E-07 -3.14483E-06 2.83152E-06 1.16496E-06 A6 -5.16686E-09 -1.98499E-10 8.67123E-10 -7.65792E-09 A8 3.82098E-11 -5.30620E-12 -1.06632E-11 -8.49581E-12 A10 -1.08565E-13 -2.87197E-14 -4.64511E-14 7.86908E-13 A12 -2.03240E-16 1.08836E-16 1.87428E-16 -6.73161E-15 A14 4.83533E-19 -4.94374E-19 -1.02921E-19 2.04431E-17 A16 1.76105E-21 -8.27912E-22 -6.14286E-22 8.18003E-21 A18 4.40341E-24 1.11878E-23 -1.08374E-25 -1.79202E-22 A20 -6.76496E-27 -2.44641E-26 -2.83106E-27 2.86343E-25 [Various data] Zoom ratio 3.59 Wide-angle Mid-range Telephoto Focal length 28.55 50.00 102.37 F-number 2.91 2.91 2.91 Full angle of view 2ω 77.11 45.44 22.75 Image height Y 21.63 21.63 21.63 Lens total length 174.47 191.98 216.16 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.5000 19.0108 43.1924 d12 28.3520 15.6537 1.5000 d17 7.8170 2.8418 1.5000 d24 2.3042 2.1000 5.7383 d27 4.4853 22.3631 34.2202 BF 27.8972 27.8972 27.8972 [Lens group data] Group Starting plane Focal length G1 1 122.23 G2 6 -24.48 G3 13 98.83 G4 18 38.56 G5 25 -74.21 G6 28 -2027.04 [Example]

[0086] FIG. 4 is a lens configuration diagram of a variable magnification optical system according to a second embodiment of the present invention.

[0087] Example 2 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, the sixth lens group G6 corresponding to the final lens group GL.

[0088] When zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. Note that the sixth lens group G6 remains fixed relative to the image plane I during zooming.

[0089] When focusing from the infinity end to the closest end, the fourth lens group G4 moves toward the object side along the optical axis.

[0090] The first lens group G1 consists of, in order from the object side, a cemented lens made of a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the object side, and a positive meniscus lens with a convex surface facing the object side.

[0091] The second lens group G2 consists of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0092] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, and a negative meniscus lens L3n with its convex surface facing the image side.

[0093] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens of a biconcave lens L4n and a biconvex lens, and a positive meniscus lens with its convex surface facing the image side.

[0094] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens.

[0095] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens and a cemented lens made up of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0096] 5A, 5B, and 5C are longitudinal aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 2. Figures 6A, 6B, and 6C are lateral aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 2. It can be seen from each aberration diagram that the variable magnification optical system according to this example has excellent correction of various aberrations from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0097] The values ​​of the specifications of the variable magnification optical system according to the second embodiment of the present invention are shown below. Numerical Example 2 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 105.4246 2.2000 1.84666 23.78 0.6192 2 65.6220 7.9883 1.43700 95.10 0.5336 3 380.4578 0.2000 4 62.8083 7.3452 1.69680 55.46 0.5426 5 463.1598 (d5) 6* 794.8344 1.5000 1.77377 47.17 0.5557 7* 20.8730 7.8298 8 -52.7479 1.4000 1.77250 49.63 0.5504 9 31.7096 8.7901 1.78880 28.43 0.6009 10 -50.8125 5.1631 11* -21.5511 1.0000 1.69350 53.18 0.5482 12* -30.7363 (d12) 13 (Aperture) ∞ 1.5000 14* 54.5279 9.8495 1.59201 67.02 0.5358 15* -40.4818 0.8101 16 -36.2770 1.5000 1.73800 32.33 0.5900 17 -65.8424 (d17) 18* 109.0144 7.2343 1.59201 67.02 0.5358 19* -43.4869 0.1500 20 -79.3194 1.0000 1.73800 32.33 0.5900 21 109.0743 5.3589 1.43700 95.10 0.5336 22 -58.5192 0.1500 23 -167.4864 5.0286 1.43700 95.10 0.5336 24 -34.4017 (d24) 25 3308.8170 2.5191 1.90110 27.06 0.6072 26 -86.6130 1.0000 1.69680 55.46 0.5426 27 37.2005 (d27) 28 45.9518 10.2533 1.59282 68.62 0.5440 29 -73.3083 2.3558 30 -90.4231 1.5000 1.91082 35.25 0.5822 31 26.0260 8.0319 1.68948 31.02 0.5987 32* 106.7239 (BF) Image plane ∞ [Aspherical data] 6th floor 7th floor 11th floor 12th floor 14th floor K 0.00000 -1.00000 -1.00000 0.00000 0.00000 A4 2.76955E-06 1.43228E-05 -9.95473E-06 -2.65543E-06 -1.41121E-06 A6 1.01492E-08 3.83685E-08 3.42318E-09 2.93499E-09 2.34821E-09 A8 -1.88793E-11 7.32592E-11 -4.71186E-11 -7.97783E-11 1.85880E-12 A10 1.42142E-14 2.67619E-13 -1.91440E-13 4.17562E-13 2.28014E-14 A12 -3.75173E-19 -2.30089E-15 2.43675E-15 -1.20576E-15 -8.63512E-17 A14 -7.00838E-20 2.63902E-17 -7.57236E-18 0.00000E+00 6.98636E-20 A16 9.63513E-23 -5.44577E-20 0.00000E+00 0.00000E+00 1.12301E-21 A18 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 3.14040E-24 A20 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 2.94008E-28 Face 15, Face 18, Face 19, Face 32 K 0.00000 0.00000 0.00000 0.00000 A4 1.32972E-06 -6.02146E-06 5.99112E-06 -1.92263E-06 A6 5.30076E-09 -1.51199E-10 -2.41223E-09 1.10​​​​​​​​​​​​​​​​[Various data] Zoom ratio 3.53 Wide-angle Mid-range Telephoto Focal length 28.84 50.00 101.85 F-number 2.91 2.91 2.91 Full angle of view 2ω 76.52 46.48 22.85 Image height Y 21.63 21.63 21.63 Lens total length 173.06 186.36 213.01 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.5000 11.1198 34.7507 d12 23.9417 12.0612 1.5000 d17 16.0983 7.2089 9.9999 d24 4.2688 1.5000 1.5001 d27 7.7448 34.9654 45.7482 BF 17.8494 17.8494 17.8494 [Lens group data] Group Starting plane Focal length G1 1 98.08 G2 6 -22.18 G3 13 62.11 G4 18 43.52 G5 25 -62.25 G6 28 -848.99 [Example]

[0098] FIG. 7 is a lens configuration diagram of a variable magnification optical system according to a third embodiment of the present invention.

[0099] Example 3 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, the sixth lens group G6 corresponding to the final lens group GL.

[0100] When zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 remains constant, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. Note that the sixth lens group G6 is fixed relative to the image plane I during zooming.

[0101] During focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0102] The first lens group G1 consists of, in order from the object side, a cemented lens made of a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the object side, and a positive meniscus lens with a convex surface facing the object side.

[0103] The second lens group G2 consists of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0104] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, and a cemented lens formed by cementing a biconcave lens L3n and a biconvex lens.

[0105] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens formed by cementing a biconcave lens L4n and a biconvex lens, and a biconvex lens.

[0106] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens.

[0107] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens, and a cemented lens made up of a positive meniscus lens with its convex surface facing the image side and a biconcave lens.

[0108] 8A, 8B, and 8C are longitudinal aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 3. Figures 9A, 9B, and 9C are lateral aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 3. It can be seen from each aberration diagram that the variable magnification optical system according to this example has excellent correction of various aberrations from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0109] The values ​​of the specifications of the variable magnification optical system according to the third embodiment of the present invention are shown below. Numerical Example 3 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 179.2084 2.0000 1.92286 20.88 0.6390 2 97.3898 7.1756 1.43700 95.10 0.5336 3 758.6539 0.2000 4 82.2327 6.7190 1.85033 42.70 0.5646 5 310.3818 (d5) 6* 128.5311 2.0000 1.85135 40.10 0.5695 7* 20.4306 8.4477 8 -68.8600 1.2000 1.69680 55.46 0.5426 9 40.0193 8.2181 1.77047 29.74 0.5951 10 -43.1870 2.1249 11* -26.9006 1.1000 1.69350 53.20 0.5467 12* -73.7285 (d12) 13 (Aperture) ∞ 1.5000 14* 44.1647 4.4207 1.59201 67.02 0.5358 15* -171.8607 3.4330 16 -85.1998 1.3000 1.76200 40.10 0.5765 17 46.8813 6.0871 1.77047 29.74 0.5951 18 -355.0483 (d18) 19 50.9169 7.6422 1.43700 95.10 0.5336 20 -47.4451 5.1924 21 -58.7592 1.0000 1.78880 28.42 0.6006 22 48.8761 5.7543 1.43700 95.10 0.5336 23 -93.8745 0.1500 24* 45.1526 6.9034 1.69350 53.20 0.5467 25* -55.1319 (d25) 26 173.5508 2.4342 1.84666 23.78 0.6192 27 -260.9119 1.0000 1.69680 55.46 0.5426 28 40.1664 (d28) 29 64.3701 7.7587 1.59349 67.00 0.5366 30 -86.4580 1.7944 31 -207.3852 5.5341 1.43700 95.10 0.5336 32 -44.6083 3.5810 1.80610 40.73 0.5694 33* 74.3189 (BF) Image plane ∞ [Aspherical data] 6th floor 7th floor 11th floor 12th floor 14th floor K 0.00000 -1.00000 -1.00000 0.00000 0.00000 A4 4.11166E-06 1.81379E-05 7.03885E-06 6.10735E-06 -4.59577E-06 A6 1.25714E-09 3.91055E-08 -1.45963E-09 -1.56970E-08 2.10732E-08 A8 -8.47626E-12 1.30567E-10 -1.29399E-10 -1.25650E-10 -1.92526E-10 A10 -5.74457E-16 -3.61282E-13 9.38107E-13 9.50079E-13 8.48013E-13 A12 3.74980E-18 2.14933E-15 -2.24300E-15 -2.48285E-15 -1.29928E-15 15 pages 24 pages 25 pages 33 pages K 0.00000 0.00000 0.00000 0.00000 A4 2.03345E-07 -4.96087E-06 3.01099E-06 8.76780E-07 A6 1.75354E-08 1.71047E-09 -1.74050E-11 -8.36878E-10 A8 -1.38485E-10 7.75114E-12 3.64239E-12 1.97059E-11 A10 5.52442E-13 -2.87970E-14 2.79577E-15 -8.33180E-14 A12 -7.13866E-16 1.50074E-17 -3.61072E-17 1.08144E-16 [Various data] Zoom ratio 3.34 Wide-angle Mid-range Telephoto Focal length 24.72 50.00 82.45 F-number 2.91 2.91 2.91 Full angle of view 2ω 86.47 46.04 28.04 Image height Y 21.63 21.63 21.63 Lens total length 171.89 186.12 216.15 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.6000 14.6473 44.4418 d12 25.4627 6.3833 1.5000 d18 8.9856 2.8620 1.5746 d25 1.6161 1.6161 1.6161 d28 7.2617 33.6478 40.0465 BF 22.2969 22.2969 22.2969 [Lens group data] Group Starting plane Focal length G1 1 137.60 G2 6 -23.06 G3 13 93.71 G4 19 37.30 G5 26 -85.24 G6 29 -365.25 [Example]

[0110] FIG. 10 is a lens configuration diagram of a variable magnification optical system according to a fourth embodiment of the present invention.

[0111] Example 4 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, the sixth lens group G6 corresponding to the final lens group GL.

[0112] When zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. Note that the second lens group G2 and the sixth lens group G6 are fixed relative to the image plane I during zooming.

[0113] During focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0114] The first lens group G1 is composed of, in order from the object side, a cemented lens of a negative meniscus lens with a convex surface facing the object side and a biconvex lens, and a positive meniscus lens with a convex surface facing the object side.

[0115] The second lens group G2 consists of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0116] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a biconvex lens, and a negative meniscus lens L3n with its convex surface facing the image side.

[0117] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens formed by cementing a biconcave lens L4n and a biconvex lens, and a biconvex lens.

[0118] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens on the object side.

[0119] The sixth lens group G6 is composed of, in order from the object side, a cemented lens consisting of a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the image side.

[0120] 11A, 11B, and 11C are longitudinal aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 4. FIGS. 12A, 12B, and 12C are lateral aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 4. It can be seen from the aberration diagrams that the variable magnification optical system according to this example has excellent imaging performance, with various aberrations being well corrected from the wide-angle end to the telephoto end.

[0121] The values ​​of the specifications of the variable magnification optical system according to the fourth embodiment of the present invention are shown below. Numerical Example 4 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 182.8962 2.0000 1.84666 23.78 0.6192 2 103.0096 7.8692 1.43700 95.10 0.5336 3 -365.4120 0.2000 4 61.6580 5.8612 1.65160 58.54 0.5390 5 159.2619 (d5) 6* 180.0000 1.5000 1.77377 47.17 0.5557 7* 23.4545 8.5012 8 -44.9965 1.4000 1.75500 52.32 0.5473 9 42.1796 8.3914 1.78880 28.43 0.6009 10 -45.3736 1.8722 11* -24.4401 1.1000 1.69350 53.20 0.5467 12* -51.1814 (d12) 13 (Aperture) ∞ 1.5000 14* 49.5659 7.9295 1.55332 71.69 0.5404 15* -107.8543 0.1500 16 231.7407 4.9404 1.43700 95.10 0.5336 17 -139.4126 4.1037 18 -34.5320 1.5000 1.78590 43.94 0.5612 19 -55.9426 (d19) 20* 150.0000 7.4430 1.59201 67.02 0.5358 21* -46.2774 0.1000 22 -343.7916 1.0000 1.73800 32.33 0.5900 23 46.0034 7.3560 1.43700 95.10 0.5336 24 -85.1870 0.1000 25 110.0127 5.9425 1.49700 81.61 0.5389 26 -57.2477 (d26) 27 251.5218 2.7660 1.84666 23.78 0.6192 28 -251.5218 1.0000 1.69680 55.46 0.5426 29 48.3062 (d29) 30 55.7665 1.5000 1.61266 44.46 0.5640 31 28.9959 6.2338 1.45562 91.31 0.5343 32* 50.0000 (BF) Image plane ∞ [Aspherical data] 6th floor 7th floor 11th floor 12th floor 14th floor K 0.00000 -1.00000 0.00000 0.00000 0.00000 A4 1.16303E-05 2.10660E-05 1.01208E-05 5.91951E-06 -1.92131E-06 A6 -2.39263E-08 2.09856E-08 -5.16644E-09 -2.37582E-08 5.12733E-09 A8 5.61904E-11 3.43417E-12 -1.88011E-10 -1.23913E-10 -1.80837E-11 A10 -7.63279E-14 2.81058E-13 7.79977E-14 8.32342E-13 4.92591E-14 A12 5.26804E-17 6.69872E-16 9.39229E-15 -2.12598E-15 -3.03032E-17 A14 0.00000E+00 0.00000E+00 -1.45805E-17 7.29516E-19 0.00000E+00 A十六 0.00000E+00 0.00000E+00 -4.99286E-19 1.20374E-20 0.00000E+00 A18 0.00000E+00 0.00000E+00 3.13435E-21 -8.26278E-23 0.00000E+00 A20 0.00000E+00 0.00000E+00 -5.89066E-24 1.47495E-25 0.00000E+00 Faces 15, 20, 21, 32 K 0.00000 0.00000 0.00000 0.00000 A4 -1.13073E-07 -3.06852E-06 3.92015E-06 1.40386E-06 A6 2.29101E-09 8.76708E-09 6.20425E-09 2.27926E-09 A8 -1.42414E-12 -2.00766E-12 -9.11955E-12 1.10032E-11 A10 1.66462E-16 9.45764E-14 1.04572E-13 -6.04579E-14 It should be noted that in the translation of "A十六" above, it is assumed that "A16" is what is meant. If there is a more specific naming convention for this "A十六", it may need to be adjusted accordingly.A12 0.00000E+00 -2.95097E-17 3.55952E-17 1.34174E-16 A14 0.00000E+00 -4.34122E-20 -1.09199E-19 -8.90788E-20 A16 0.00000E+00 -2.78767E-22 -3.13092E-22 0.00000E+00 A18 0.00000E+00 -4.85803E-25 -2.28248E-25 0.00000E+00 A20 0.00000E+00 1.90227E-27 1.54201E-27 0.00000E+00 [Various data] Zoom ratio 4.04 Wide-angle Mid-range Telephoto Focal length 28.84 50.00 116.39 F-number 2.91 2.91 2.91 Full angle of view 2ω 77.45 45.78 20.07 Image height Y 21.63 21.63 21.63 Lens length 171.24 186.47 216.95 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.6000 16.8210 47.3085 d12 25.2100 13.4960 1.5000 d19 9.8970 4.8225 1.7139 d26 6.4176 2.5815 1.7513 d29 13.3242 33.9488 49.8835 BF 22.5352 22.5352 22.5352 [Lens group data] Group Starting plane Focal length G1 1 118.28 G2 6 -22.46 G3 13 73.66 G4 20 40.83 G5 27 -96.53 G6 30 -315.04 [Example]

[0122] FIG. 13 is a lens configuration diagram of a variable magnification optical system according to a fifth embodiment of the present invention.

[0123] Example 5 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, the sixth lens group G6 corresponding to the final lens group GL.

[0124] When zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 increases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. Note that the sixth lens group G6 is fixed relative to the image plane I during zooming.

[0125] During focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0126] The first lens group G1 is composed of, in order from the object side, a cemented lens of a negative meniscus lens with a convex surface facing the object side and a biconvex lens, and a positive meniscus lens with a convex surface facing the object side.

[0127] The second lens group G2 consists of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0128] The third lens group G3 consists of, in order from the object side, an aperture stop S, a biconvex lens, a cemented lens of a biconvex lens and a negative meniscus lens with its convex surface facing the image side, and a cemented lens of a biconcave lens L3n and a biconvex lens.

[0129] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens formed by cementing a biconcave lens L4n and a biconvex lens, and a biconvex lens.

[0130] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens.

[0131] The sixth lens group G6 is composed of, in order from the object side, a negative meniscus lens with its convex surface facing the object side, and a cemented lens made up of a biconvex lens and a biconcave lens.

[0132] 14A, 14B, and 14C are longitudinal aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 5. Figures 15A, 15B, and 15C are lateral aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 5. It can be seen from each aberration diagram that the variable magnification optical system according to this example has excellent correction of various aberrations from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0133] The values ​​of the specifications of the variable magnification optical system according to the fifth embodiment of the present invention are shown below. Numerical Example 5 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 208.4271 2.0000 1.92119 23.96 0.6202 2 101.0804 8.4799 1.43700 95.10 0.5336 3 -400.0316 0.2000 4 72.5256 6.2454 1.77250 49.63 0.5504 5 249.9764 (d5) 6* 108.6663 1.6000 1.69350 53.20 0.5467 7* 19.7189 8.5536 8 -43.4806 1.4000 1.69680 55.46 0.5426 9 26.3610 7.7853 1.72047 34.71 0.5834 10 -40.7874 1.6235 11* -25.0635 1.1000 1.59201 67.02 0.5358 12* -80.3927 (d12) 13 (Aperture) ∞ 1.5000 14 64.4130 4.5545 1.55032 75.50 0.5401 15 -104.7718 0.1500 16 66.3146 10.5596 1.59282 68.62 0.5440 17 -29.8329 1.0000 1.74400 44.90 0.5631 18 -122.5985 1.3551 19 -55.4177 1.0000 1.74951 35.33 0.5818 20 37.8660 6.2752 1.78880 28.42 0.6006 21 -187.4083 (d21) 22* 112.8619 5.3142 1.69350 53.20 0.5467 23 -50.2663 0.1000 24 -72.2356 1.0000 1.73037 32.23 0.5899 25 38.9142 8.7116 1.43700 95.10 0.5336 26 -58.3377 0.1000 27 88.5131 4.3130 1.75500 52.32 0.5473 28 -110.2222 (d28) 29 119.3467 2.2385 1.68430 26.81 0.6232 30 -1232.6333 1.0000 1.59349 67.00 0.5366 31 34.6525 (d31) 32* 42.4586 1.5000 1.69350 53.20 0.5467 33 20.7326 17.7531 1.48749 70.44 0.5306 34 -25.6377 1.5000 1.75500 52.32 0.5473 35 580.8799 (BF) Image plane ∞ [Aspherical data] 6th floor 7th floor 11th floor 12th floor 22nd floor K 0.00000 -1.00000 -1.00000 0.00000 0.00000 A4 1.20562E-06 1.68701E-05 -7.87056E-06 -5.89962E-06 -5.83684E-06 A6 1.04119E-09 2.25846E-08 -3.83060E-09 -3.64429E-10 2.87448E-09 A8 2.20890E-11 1.56178E-10 -1.12975E-11 -3.79056E-11 2.46921E-12 A10 -7.44295E-14 -4.74431E-13 -3.26102E-14 1.12067E-13 -2.02116E-14 A12 8.84713E-17 2.83689E-15 -4.06654E-16 -4.97873E-16 3.35568E-17 32 sides K 0.00000 A4 3.47196E-06 A6 1.73401E-09 A8 2.14902E-11 A10 -5.79139E-14 A12 7.95386E-17 [Various data] Zoom ratio 3.53 Wide-angle Mid-range Telephoto Focal length 28.84 50.00 101.85 F-number 2.91 2.91 2.91 Full angle of view 2ω 77.73 45.64 22.86 Image height Y 21.63 21.63 21.63 Lens total length 175.20 191.20 215.20 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.6000 19.1285 44.6731 d12 24.7655 13.0295 1.5000 d21 8.3406 3.0682 1.5000 d28 3.2854 1.5000 3.8471 d31 5.2443 22.5095 31.7156 BF 23.0485 23.0485 23.0485 [Lens group data] Group Starting plane Focal length G1 1 118.97 G2 6 -22.01 G3 13 60.94 G4 22 41.59 G5 29 -89.87 G6 32 -243.27 [Example]

[0134] FIG. 16 is a lens configuration diagram of a variable magnification optical system according to a sixth embodiment of the present invention.

[0135] Example 6 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power, the fifth lens group G5 corresponding to the final lens group GL.

[0136] When changing magnification from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, and the distance between the fourth lens group G4 and the fifth lens group G5 increases.

[0137] During focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0138] The first lens group G1 consists of, in order from the object side, a cemented lens made of a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the object side, and a positive meniscus lens with a convex surface facing the object side.

[0139] The second lens group G2 consists of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0140] The third lens group G3 consists of, in order from the object side, an aperture stop S, a biconvex lens, a cemented lens consisting of a biconvex lens and a negative meniscus lens with its convex surface facing the image side, and a negative meniscus lens L3n with its convex surface facing the image side.

[0141] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens formed by cementing a biconcave lens L4n and a biconvex lens, and a biconvex lens.

[0142] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens.

[0143] 17A, 17B, and 17C are longitudinal aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 6. Figures 18A, 18B, and 18C are lateral aberration diagrams, respectively, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end, according to Example 6. It can be seen from each aberration diagram that the variable magnification optical system according to this example has excellent correction of various aberrations from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0144] The specifications of the sixth embodiment of the present invention are shown below. Numerical Example 6 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 151.4338 2.0000 1.84666 23.78 0.6192 2 70.1091 8.0563 1.43700 95.10 0.5336 3 1161.4935 0.2000 4 66.2043 6.0728 1.85033 42.70 0.5646 5 312.9615 (d5) 6* 200.0000 2.0000 1.77377 47.17 0.5557 7* 21.1321 8.4708 8 -42.6075 1.4000 1.77250 49.63 0.5504 9 38.2830 8.9449 1.78880 28.43 0.6009 10 -39.5257 1.8540 11* -23.7321 1.1000 1.69350 53.18 0.5482 12* -42.9357 (d12) 13 (Aperture) ∞ 1.5000 14* 52.5953 8.2497 1.55332 71.69 0.5404 15 -72.2621 3.6518 16 100.4069 7.2700 1.43700 95.10 0.5336 17 -59.3146 1.0000 1.61266 44.46 0.5640 18 -168.3586 2.6430 19 -39.9587 1.2000 1.61266 44.46 0.5640 20 -163.0217 (d20) 21 40.5789 9.1529 1.43700 95.10 0.5336 22 -48.2149 0.1500 23 -142.8106 1.0000 1.73800 32.33 0.5900 24 68.5186 4.7884 1.43700 95.10 0.5336 25 -98.8788 0.1500 26* 61.2750 4.1724 1.55332 71.69 0.5404 27* -155.5945 (d27) 28 235.0137 2.0828 1.90110 27.06 0.6072 29 -235.0137 1.0000 1.59201 67.02 0.5358 30* 33.8176 (BF) Image plane ∞ [Aspherical data] 6th floor 7th floor 11th floor 12th floor 14th floor K 0.00000 -1.00000 0.00000 0.00000 0.00000 A4 3.70073E-06 1.63899E-05 1.28947E-06 -3.55106E-06 -1.22372E-06 A6 6.14079E-09 3.25507E-08 -4.61728E-09 -1.07358E-08 2.34962E-09 A8 -9.49773E-12 1.85692E-10 1.35851E-12 -2.52869E-11 -1.97772E-11 A10 -5.84650E-14 -5.74426E-13 -7.92797E-14 6.54028E-14 8.05280E-14 A12 2.06524E-16 -5.45136E-16 -2.37081E-16 -9.86488E-17 -1.33920E-16 A14 2.35109E-19 9.58085E-18 2.37094E-18 -3.72934E-19 0.00000E+00 A16 -8.48033E-22 1.36466E-19 1.89493E-21 -3.01643E-21 0.00000E+00 A18 -2.62794E-24 -7.31630E-22 -5.98903E-23 -1.01052E-23 0.00000E+00 A20 5.95733E-27 9.06212E-25 -1.49863E-25 -9.24719E-27 0.00000E+00 26th surface, 27th surface, 30th surface K 0.00000 0.00000 0.00000​​​​​​​​​​​​​​​A18 0.00000E+00 0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 3.53 Wide-angle Mid-range Telephoto Focal length 28.84 50.00 101.85 F-number 2.91 2.91 2.91 Full angle of view 2ω 77.75 46.13 22.91 Image height Y 21.63 21.63 21.63 Lens total length 174.18 182.80 200.08 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.6000 14.9546 38.0109 d12 28.7190 15.1911 1.5000 d20 8.8423 2.1453 1.5000 d27 3.1328 1.7994 5.3513 BF 43.7729 60.6013 65.6048 [Lens group data] Group Starting plane Focal length G1 1 104.20 G2 6 -22.76 G3 13 71.83 G4 21 39.69 G5 28 -81.75 [Example]

[0145] FIG. 19 is a diagram showing a lens configuration according to Example 7 of the present invention.

[0146] Example 7 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, the sixth lens group G6 corresponding to the final lens group GL.

[0147] When zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 increases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. Note that the sixth lens group G6 is fixed relative to the image plane I during zooming.

[0148] During focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0149] The first lens group G1 is composed of, in order from the object side, a cemented lens of a negative meniscus lens with a convex surface facing the object side and a biconvex lens, and a positive meniscus lens with a convex surface facing the object side.

[0150] The second lens group G2 consists of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0151] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, and a cemented lens consisting of a biconvex lens and a negative meniscus lens L3n with its convex surface facing the image side.

[0152] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens of a biconcave lens L4n and a biconvex lens, and a positive meniscus lens with its convex surface facing the image side.

[0153] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens.

[0154] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens and a cemented lens made up of a biconvex lens and a biconcave lens.

[0155] 20A, 20B, and 20C are longitudinal aberration diagrams, respectively, according to Example 7, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end. 21A, 21B, and 21C are lateral aberration diagrams, respectively, according to Example 7, when focusing on an object at infinity at the wide-angle end, at an intermediate focal length, and at the telephoto end. It can be seen from the aberration diagrams that the variable magnification optical system according to this example has excellent correction of various aberrations from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0156] The specifications of the seventh embodiment of the present invention are shown below. Numerical Example 7 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 339.1037 2.2000 1.84666 23.78 0.6192 2 140.5622 6.3134 1.43700 95.10 0.5336 3 -256.2897 0.2000 4 75.0019 4.9733 1.69680 55.46 0.5426 5 218.0286 (d5) 6* 96.2508 1.5000 1.69350 53.18 0.5482 7* 22.9090 9.5225 8 -52.4864 1.4000 1.69680 55.46 0.5426 9 39.6244 9.9269 1.68960 31.14 0.6031 10 -50.6074 3.3000 11* -26.2180 1.2000 1.58913 61.25 0.5374 12* -63.8015 (d12) 13 (Aperture) ∞ 1.5000 14* 124.7274 4.2858 1.55332 71.69 0.5404 15* -124.7274 5.4144 16 103.5446 8.1345 1.55032 75.50 0.5401 17 -65.5833 1.5000 1.72342 37.99 0.5820 18 -239.8010 (d18) 19* 175.4916 5.7946 1.55332 71.69 0.5404 20* -71.0848 1.9685 21 -300.0000 1.0000 1.73800 32.26 0.5896 22 76.8744 8.9856 1.43700 95.10 0.5336 23 -76.4879 0.1500 24 -3011.9276 6.0032 1.55032 75.50 0.5401 25 -60.2741 (d25) 26 329.0123 3.0206 1.80610 33.27 0.5884 27 -142.6606 1.0000 1.58913 61.25 0.5403 28 44.0347 (d28) 29* 70.0105 6.0695 1.58913 61.25 0.5374 30* -790.6205 4.3136 31 781.5251 9.2092 1.71338 26.04 0.6297 32 -25.0000 1.5000 2.00100 29.13 0.5995 33 203.9971 (BF) Image plane ∞ [Aspherical data] 6th floor 7th floor 11th floor 12th floor 14th floor K 0.00000 -1.00000 -1.00000 0.00000 0.00000 A4 2.52743E-06 1.25164E-05 -5.62862E-06 -2.92132E-06 -8.88979E-07 A6 3.88924E-09 2.12690E-08 4.55818E-10 1.20480E-09 -7.62713E-11 A8 -8.08322E-12 1.47497E-11 -7.74093E-12 -1.71475E-11 -4.15453E-13 A10 -1.20972E-15 1.64395E-13 -5.74930E-15 2.90325E-14 1.60017E-15 A12 2.57303E-17 6.83255E-17 -5.09029E-17 -8.06100E-17 -1.93054E-18 A14 4.58729E-20 -2.41670E-18 -5.06920E-21 0.00000E+00 -3.91589E-21 A16 -1.33950E-22 1.07440E-20 0.00000E+00 0.00000E+00 2.52162E-24 Surfaces 15, 19, 20, 29, 30 K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 8.88979E-07 -2.87210E-06 1.45965E-06 1.61088E-06 -1.15575E-06 A6 7.62713E-11 -4.44054E-10 -1.54529E-09 -4.09547E-09 -6.65759E-09 A8 4.15453E-13 -1.06285E-12 -4.59893E-13 1.49129E-11 4.72510E-12 A10 -1.60017E-15 1.59240E-15 1.36187E-15 -4.56037E-14 6.83774E-15 A12 1.93054E-18 5.06526E-19 0.00000E+00 1.29060E-16 -5.42388E-17 A14 3.91589E-21 0.00000E+00 0.00000E+00 -3.03434E-19 -1.01492E-19 A16 -2.52162E-24 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 3.63 Wide-angle Mid-range Telephoto Focal length 36.05 70.00 130.94 F-number 2.91 2.91 2.91 Full angle of view 2ω 64.53 33.56 18.07 Image height Y 21.63 21.63 21.63 Lens total length 199.15 215.94 249.15 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.5000 22.9692 50.4666 d12 29.2284 9.9146 1.5000 d18 14.3979 7.2216 5.6123 d25 1.5000 4.7540 2.3627 d28 13.5105 32.0582 50.1953 BF 28.6321 28.6321 28.6321 [Lens group data] Group Starting plane Focal length G1 1 133.71 G2 6 -25.60 G3 13 70.86 G4 19 55.52 G5 26 -107.23 G6 29 -228.64 [Example]

[0157] FIG. 22 is a diagram showing a lens configuration according to Example 8 of the present invention.

[0158] Example 8 comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power, the seventh lens group G7 corresponding to the final lens group GL.

[0159] When zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, and the distance between the sixth lens group G6 and the seventh lens group G7 increases. Note that the seventh lens group G7 is fixed relative to the image plane I during zooming.

[0160] During focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0161] The first lens group G1 is composed of, in order from the object side, a cemented lens of a negative meniscus lens with a convex surface facing the object side and a biconvex lens, and a positive meniscus lens with a convex surface facing the object side.

[0162] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens with a convex surface facing the image side.

[0163] The third lens group G3 consists of, in order from the object side, an aperture stop S, a biconvex lens, a cemented lens consisting of a negative meniscus lens with its convex surface facing the object side and a biconvex lens, and a negative meniscus lens L3n with its convex surface facing the image side. To compensate for image blurring, the second cemented lens from the object side of the third lens group G3, consisting of a negative meniscus lens with its convex surface facing the object side and a biconvex lens, moves in a direction approximately perpendicular to the optical axis.

[0164] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a cemented lens formed by cementing a biconcave lens L4n and a biconvex lens, and a biconvex lens.

[0165] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconvex lens and a biconcave lens.

[0166] The sixth lens group G6 is composed of, in order from the object side, a cemented lens consisting of a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the object side.

[0167] The seventh lens group G7 is made up of a biconcave lens.

[0168] 23A, 23B, and 23C are longitudinal aberration diagrams according to Example 8 when focusing on an object at infinity at the wide-angle end, at a mid-focal length, and at the telephoto end, respectively. 24A, 24B, and 24C are lateral aberration diagrams according to Example 8 when focusing on an object at infinity at the wide-angle end, at a mid-focal length, and at the telephoto end, respectively. 25A, 25B, and 25C are lateral aberration diagrams according to Example 8 when image stabilization is performed at an image blur correction angle of 0.3° when focusing on an object at infinity at the wide-angle end, at a mid-focal length, and at the telephoto end, respectively. It can be seen from the aberration diagrams that the variable magnification optical system according to this example has excellent imaging performance, with various aberrations being well corrected from the wide-angle end to the telephoto end.

[0169] The specifications of the eighth embodiment of the present invention are shown below. Numerical Example 8 Unit: mm [Face Data] Surface number rd nd vd PgF Object surface ∞ (d0) 1 499.9435 2.2000 1.84666 23.78 0.6192 2 144.7637 6.1705 1.55397 71.76 0.5392 3 -430.4265 0.2000 4 73.3119 5.9391 1.69680 55.46 0.5426 5 234.0640 (d5) 6 80.9176 2.0000 1.72916 54.67 0.5453 7 21.4319 8.7809 8* -41.0107 1.4000 1.59201 67.02 0.5358 9* 45.3855 1.0000 10 45.2496 7.5917 1.78880 28.43 0.6009 11 -56.9689 3.7108 12 -28.1571 1.1000 1.74400 44.90 0.5631 13 -100.3347 (d13) 14 (Aperture) ∞ 1.5000 15* 46.9306 5.5542 1.55332 71.69 0.5404 16 -100.0616 2.7922 17 73.7153 1.5000 2.05090 26.94 0.6052 18 40.3515 5.9670 1.60342 38.01 0.5828 19 -239.6272 4.4583 20 -47.0826 1.0000 1.80000 29.84 0.6017 21 -106.2236 (d21) 22* 95.2593 4.5814 1.59201 67.02 0.5358 23 -64.1779 0.1501 24 -999.7999 1.0000 1.73037 32.23 0.5899 25 48.5191 6.6608 1.43700 95.10 0.5336 26 -78.7307 0.1499 27 202.4146 5.1695 1.61997 63.88 0.5426 28 -54.3868 (d28) 29 115.2381 2.5505 1.94594 17.98 0.6546 30 -353.7179 1.0000 1.74951 35.33 0.5818 31 34.1537 (d31) 32* 37.9282 1.5000 1.69350 53.20 0.5467 33 25.0001 8.8108 1.48749 70.44 0.5306 34 237.6160 (d34) 35* -73.1774 1.5000 1.59201 67.02 0.5358 36 170.9535 (BF) Image plane ∞ [Aspherical data] 8 screens 9 screens 15 screens 22 screens 32 screens K -0.85184 -0.20744 0.00000 0.00000 0.00000 A4 2.35829E-06 -2.26040E-06 -3.03509E-06 -8.62482E-06 2.63691E-06 A6 -2.10031E-09 -2.22191E-09 -2.16063E-09 5.65772E-09 2.83322E-09 A8 3.58519E-11 -3.61157E-11 8.28785E-12 -5.07322E-12 2.18327E-11 A10 -2.00394E-14 4.58221E-13 -4.05259E-15 -2.17785E-15 -4.93846E-14 A12 -1.65769E-16 -1.37930E-15 -5.12726E-17 1.27231E-17 1.07498E-16 A14 0.00000E+00 0.00000E+00 -5.46995E-20 0.00000E+00 0.00000E+00 A16 0.00000E+00 0.00000E+00 7.28438E-22 0.00000E+00 0.00000E+00 A18 0.00000E+00 0.00000E+00 2.74488E-24 0.00000E+00 0.00000E+00 A20 0.00000E+00 0.00000E+00 -1.18341E-26 0.00000E+00 0.00000E+00 35 sides K 0.00000 A4 -5.19869E-06 A6 -1.23838E-08 A8 2.03578E-11 A10 -1.20432E-13 A12 -3.44965E-17 A14 0.00000E+00 A16 0.00000E+00 A18 0.00000E+00 A20 0.00000E+00 [Various data] Zoom ratio 3.53 Wide-angle Mid-range Telephoto Focal length 28.84 50.00 101.85 F-number 2.91 2.91 2.91 Full angle of view 2ω 76.54 45.95 22.86 Image height Y 21.63 21.63 21.63 Lens total length 165.28 174.96 213.68 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 1.5000 12.9773 47.0554 d13 23.1216 8.5990 1.5000 d21 9.5256 3.7785 1.5000 d28 1.0000 2.2639 0.9993 d31 3.7632 19.7057 35.5544 d34 6.3647 7.6305 7.0630 BF 24.0717 24.0717 24.0717 [Lens group data] Group Starting plane Focal length G1 1 131.71 G2 6 -22.77 G3 14 64.66 G4 22 37.48 G5 29 -77.88 G6 32 120.73 G7 35 -86.36

[0170] Next, an image pickup apparatus equipped with the variable magnification optical system of the present invention will be described with reference to FIG.

[0171] 26, 1 is an imaging device, 2 is a variable magnification optical system according to any one of Examples 1 to 8, and 3 is an imaging section built into the imaging device 1. The imaging device 1 includes an image processing engine and the like (not shown), and the imaging section 3 includes components such as a cover glass and an optical low-pass filter (not shown), and an imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor. An object (subject) (not shown) forms an image (subject image) on the imaging section 3 through the variable magnification optical system 2, and the image (subject image) is recorded in a memory (not shown) by the imaging device 1.

[0172] This allows the photographer to photograph a subject using an imaging device that is compact, has a large aperture ratio and a high zoom ratio for the zoom optical system, and is equipped with a zoom optical system in which various aberrations are well corrected.

[0173] Next, the following Table 1 shows the aberration characteristics of Examples (1 to 8) of the variable magnification optical system of the present invention, along with the corresponding values ​​of the conditional expressions of these variable magnification optical systems. Furthermore, the following Table 2 shows the aberration characteristics of comparative variable magnification optical systems, along with the corresponding values ​​of the conditional expressions of these variable magnification optical systems. The various numerical values ​​for Comparative Examples A to C listed in Table 2 were calculated using the examples described in Non-Patent Documents 1 to 3.

[0174] [Table 1] TIFF2025182227000003.tif139169

[0175] [Table 2]

[0176] The various aberration coefficients shown in Tables 1 and 2 are determined by the calculation methods described in Non-Patent Documents 1 and 2. The technical significance of the aberration coefficient is that it can explicitly express the relationship between the structure of an optical system and the aberrations and the limits of the aberration correction capability. The aberration coefficients can be expressed as components of lateral aberration on a paraxial image plane, or by normalizing the components of lateral aberration on a paraxial image plane with respect to the aperture and angle of view. Here, the aberration coefficients are calculated by the calculation method based on "Improvement of normalization (2)" described in Non-Patent Document 2. This calculation method is effective as an evaluation tool for comparing the performance of optical systems, even if the focal length, NA, and ideal image height of the variable magnification optical system vary. In Tables 1 and 2, the aberration coefficients are evaluated for both the wide-angle and telephoto ends, and chromatic aberration is evaluated at multiple wavelengths. By taking the root sum of squares (RSS) of these, a final unified evaluation can be performed. The final evaluation of the Examples and Comparative Examples was divided into three stages, and each was evaluated by the following methods. Axial chromatic aberration: ○: RSS(L)<0.0040, △: 0.0040≦RSS(L)<0.0070, ×: RSS(L)≧0.0070. Lateral chromatic aberration is: ○: RSS(T)<0.0020, △: 0.0020≦RSS(T)<0.0035, ×: RSS(T)≧0.0035. Spherical aberration: ○: RSS(I)<0.4000, △: 0.4000≦RSS(I)<0.8000, ×: RSS(I)≧0.8000. Coma aberration: ○: RSS(II)<0.0400, △: 0.0400≦RSS(II)<0.0800, ×: RSS(II)≧0.0800. Astigmatism: ○: RSS(III)<0.0040, △: 0.0040≦RSS(III)<0.0080, ×: RSS(III)≧0.0080. As can be seen from Tables 1 and 2, in the examples of the variable magnification optical system of the present invention, various aberrations are well corrected from the wide-angle end to the telephoto end.

[0177] The following contents can be appropriately adopted within the scope that does not impair the imaging performance of the variable magnification optical system of the present invention.

[0178] Although five, six, and seven-group configurations have been shown as examples of variable magnification optical systems, the present invention is not limited to these, and configurations with other numbers of groups (e.g., eight or nine groups) are also possible. Specifically, a configuration in which a flat optical filter or lens group is added to the most object-side or most image-side of the variable magnification optical system is also acceptable. Note that a lens group refers to a portion having at least one lens separated by a distance that changes when changing magnification from the wide-angle end to the telephoto end.

[0179] Generally, if a flat optical element or a lens group having a refractive power sufficiently weak compared to the focal length at the wide-angle end is added to the optical system, the effect on aberration correction will be so slight that it can be ignored, or even if adding it to the optical system does have an effect on aberration correction, it will only require a small change in the refractive power arrangement of the optical system, and will not affect the structure of the optical system.

[0180] In the examples of the variable magnification optical system, all lens surfaces having refractive power are curved and refractive, but this is not limited thereto. Graded index materials, metasurfaces, and diffractive optical elements may also be used for flat or curved surfaces. Specifically, in the variable magnification optical system of the present invention, if the object-side lens surface of the negative lens L3n located closest to the image in the third lens group G3 is a diffractive surface, the same effect as that of the present invention can be achieved even if the surface is convex toward the object. Furthermore, if the object-side lens surface of the negative lens L4n located closest to the object in the fourth lens group G4 is a diffractive surface, the same effect as that of the present invention can be achieved even if the surface is convex toward the object.

[0181] The lens surfaces that make up the variable magnification optical system may be coated with an anti-reflection coating, which can reduce flare and ghosting and produce higher contrast images.

[0182] The focal length of the variable magnification optical system or lens group, the back focus of the variable magnification optical system, the movement amount of the lens group, the refractive index, the Abbe number, the partial dispersion ratio, and the half angle of view of the variable magnification optical system can each be values ​​measured by the following methods.

[0183] The focal length of a variable magnification optical system or lens group can be measured in accordance with JIS B 7094 (Photographic lenses - Method for measuring focal length). Specifically, the test lens is placed in a holder mounted on a focal length measuring device capable of performing any of Measurement Methods 1 to 4 described in the standard, and measurement is performed. Examples of focal length measuring devices include the MB series manufactured by Pearl Optical Co., Ltd. (Measurement Method 3) and the OptiSpheric series manufactured by TriOptics (Measurement Method 1).

[0184] The back focus of a variable magnification optical system can be measured using a commercially available back focus measuring device. Specifically, the test lens is placed on a holder mounted on the measuring device and measured. Examples of back focus measuring devices include the MB series manufactured by Pearl Optical Co., Ltd. and the OptiSpheric series manufactured by TriOptics.

[0185] The amount of movement of the lens group can be measured using a commercially available surface distance measuring device. Specifically, the test lens is placed on a holder mounted on the measuring device and measured. An example of a surface distance measuring device is the OptiSurf series manufactured by TriOptics.

[0186] The refractive index, Abbe number, and partial dispersion ratio can be measured according to JIS B 7071 (Optics and Photonics - Methods for Measuring the Refractive Index of Optical Glass) or JIS K 7142 (Plastics - Methods for Determining the Refractive Index). Specifically, the test lens is processed into a shape that allows it to be placed on a holder mounted on a refractive index measuring instrument that can perform one of the measurement methods described in the standards (V-block method, minimum deviation method, or Method A for plastics), and the measurement wavelength is changed for each corresponding spectral line, and measurements are performed. Examples of refractive index measuring instruments include the KPR series (V-block method) manufactured by Shimadzu Corporation and the GMR series (minimum deviation method) manufactured by Shimadzu Corporation.

[0187] The half angle of view of a variable magnification optical system can be measured according to Non-Patent Document 3. Specifically, first, a photograph taken with the variable magnification optical system is observed directly with the naked eye, and the image circle diameter Φ is measured using a length measuring device such as a vernier caliper. Next, the half angle of view ω is calculated as arctan((Φ / 2) / f) / 2 using the focal length f obtained from the measurement described in the fourth paragraph above.

[0188] The configurations of the examples of the variable magnification optical system of the present invention have been described above, but various modifications are possible without being limited to the above-described embodiments and examples. The shapes and numerical values ​​of each part shown in the above-described numerical examples are examples for implementing the present technology, and the technical scope of the present invention should not be interpreted as being limited by these examples.

[0189] The above embodiment can have the following configurations. [Section 1] The lens has, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power, When changing magnification from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the third lens group G3 changes, and the distance between the third lens group G3 and the fourth lens group G4 changes, When focusing from the infinity end to the closest distance end, either the fourth lens group G4 or the fifth lens group G5 moves along the optical axis, the third lens group G3 has at least one negative lens, and the object-side lens surface of the negative lens L3n disposed closest to the image side in the third lens group G3 is convex toward the image side; the fourth lens group G4 has at least one negative lens, and the object-side lens surface of the negative lens L4n disposed closest to the object side in the fourth lens group G4 is convex toward the image side; A variable magnification optical system characterized by satisfying the following conditional expression: (1) 0.61 <f34 / fW<1.46 (2) 0.32 <f4 / f3<0.96 (3)-0.0085<ΔPgF1+ΔPgF2<0.0070 f34: the composite focal length of the third lens group G3 to the fourth lens group G4, where f34=1 / (Σ(1 / fn)), n=3 to 4, and fn is the focal length of the n-th lens group. fW: focal length at the wide-angle end of the variable magnification optical system f4: the focal length of the fourth lens group G4 f3: focal length of the third lens group G3 ΔPgF1: anomalous dispersion of the negative lens L3n located closest to the image in the third lens group G3, where ΔPgF1=PgF1-0.64833+0.00180×νd1. PgF1 is the partial dispersion ratio for the g-line and F-line of the negative lens L3n located closest to the image in the third lens group G3. νd1 is the Abbe number for the d-line of the negative lens L3n located closest to the image in the third lens group G3. ΔPgF2: anomalous dispersion of the negative lens L4n located closest to the object in the fourth lens group G4, where ΔPgF2=PgF2-0.64833+0.00180×νd2. PgF2 is the partial dispersion ratio for the g-line and F-line of the negative lens L4n located closest to the object in the fourth lens group G4. νd2 is the Abbe number for the d-line of the negative lens L4n located closest to the object in the fourth lens group G4. [Section 2] The present invention provides a variable magnification optical system described in [Item 1], characterized in that the following conditional expression is further satisfied: (4) 0.13<|f13| / f4L<1.25 f13: a composite focal length of the first lens group G1 to the third lens group G3, where f13=1 / (Σ(1 / fn)), n=1 to 3, and fn is the focal length of the n-th lens group. f4L: composite focal length of the fourth lens group G4 through the lens group arranged closest to the image (hereinafter referred to as the final lens group GL), where f4L=1 / (Σ(1 / fn)), n=4 to L, fn is the focal length of the nth lens group, and fL is the focal length of the final lens group GL. [Section 3] The present invention provides a variable magnification optical system according to [Item 1] or [Item 2], characterized in that the following conditional expression is further satisfied: (5) 1.12 <m4 / m3<1.56 m4: the amount of movement of the fourth lens group G4 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive) m3: the amount of movement of the third lens group G3 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive) [Section 4] The present invention provides a variable magnification optical system according to any one of [Item 1] to [Item 3], characterized in that the following conditional expressions are further satisfied: (6) 1.17<|f5| / f4<2.89 f5: focal length of the fifth lens group G5 f4: the focal length of the fourth lens group G4 [Section 5] The present invention provides a variable magnification optical system according to any one of [Item 1] to [Item 4], characterized in that the following conditional expressions are further satisfied: (7) 0.83 <m5 / m4<1.24 m5: the amount of movement of the fifth lens group G5 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive) m4: the amount of movement of the fourth lens group G4 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is considered positive) [Section 6] The present invention provides a variable magnification optical system according to any one of [Item 1] to [Item 5], characterized in that the following conditional expressions are further satisfied: (8) 1.34<|f5L| / fW<4.25 f5L: composite focal length of the fifth lens group G5 through the lens group arranged closest to the image (hereinafter referred to as the final lens group GL), where f5L=1 / (Σ(1 / fn)), n=5 to L, fn is the focal length of the nth lens group, and fL is the focal length of the final lens group GL. fW: focal length at the wide-angle end of the variable magnification optical system [Section 7] The present invention provides a variable magnification optical system according to any one of [Item 1] to [Item 6], characterized in that the following conditional expressions are further satisfied: (9) 0.51 <bfW / fW<1.85 bfW: back focus at the wide-angle end of the variable magnification optical system fW: focal length at the wide-angle end of the variable magnification optical system [Section 8] The present invention provides a variable magnification optical system according to any one of [Item 1] to [Item 7], characterized in that the following conditional expressions are further satisfied: (10) 28.56<ωW<44.11 ωW: half angle of view at the wide-angle end of the variable magnification optical system, where ωW=arctan(Y / fW) / 2, Y is the maximum image height at the wide-angle end of the variable magnification optical system, and fW is the focal length at the wide-angle end of the variable magnification optical system. [Section 9] The present invention is a variable magnification optical system described in any one of [Item 1] to [Item 8], further characterized in that, when focusing from the infinity end to the close-up end, the fourth lens group G4 moves toward the object side along the optical axis. [Section 10] The present invention is a variable magnification optical system described in any one of [Item 1] to [Item 9], further characterized in that, when focusing from the infinity end to the closest end, the fifth lens group G5 moves toward the image side along the optical axis. [Section 11] The present invention is a variable magnification optical system according to any one of [Item 1] to [Item 10], further characterized in that the object-side lens surface of the negative lens L3n arranged closest to the image in the third lens group G3 is in contact with air. [Section 12] The present invention is a variable magnification optical system according to any one of [Item 1] to [Item 11], further characterized in that the object-side lens surface of the negative lens L4n arranged closest to the object in the fourth lens group G4 is in contact with air. [Section 13] The present invention is a variable magnification optical system according to any one of [Item 1] to [Item 12], further characterized in that the first lens group G1 has at least one negative lens. [Section 14] The present invention is a variable magnification optical system according to any one of [Item 1] to [Item 13], further comprising an aperture stop S closest to the object side of the third lens group G3, wherein the third lens group G3 and the aperture stop S move together during magnification variation. [Section 15] The present invention is a variable magnification optical system according to any one of [Item 1] to [Item 14], further characterized in that the fifth lens group G5 has at least one positive lens. [Section 16] The present invention is a variable magnification optical system according to any one of [Item 1] to [Item 15], further characterized in that the second lens group G2 is fixed relative to the image plane when varying magnification from the wide-angle end to the telephoto end. [Section 17] The present invention is a variable magnification optical system according to any one of [Item 1] to [Item 16], further characterized in that, when changing magnification from the wide-angle end to the telephoto end, the lens group arranged closest to the image side (hereinafter referred to as the final lens group GL) is fixed with respect to the image plane. [Section 18] The present invention is further characterized in that the third lens group G3 has a vibration-proof lens group with positive refractive power that is movable in a direction approximately perpendicular to the optical axis. [Item 1] to [Item 17] A variable magnification optical system. [Section 19] The present invention further provides an imaging device equipped with a variable magnification optical system according to any one of [Item 1] to [Item 18]. [Explanation of symbols]

[0190] G1 First lens group G2 Second lens group G3 Third lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group GL final lens group L3n: The negative lens element in the third lens group G3 that is located closest to the image side L4n: The negative lens element in the fourth lens group G4 that is located closest to the object S aperture stop I image plane

Claims

1. The lens has, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power, When changing magnification from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the third lens group G3 changes, and the distance between the third lens group G3 and the fourth lens group G4 changes, When focusing from the infinity end to the closest distance end, either the fourth lens group G4 or the fifth lens group G5 moves along the optical axis, the third lens group G3 has at least one negative lens, and the object-side lens surface of the negative lens L3n disposed closest to the image side in the third lens group G3 is convex toward the image side; the fourth lens group G4 has at least one negative lens, and the object-side lens surface of the negative lens L4n disposed closest to the object side in the fourth lens group G4 is convex toward the image side; A variable magnification optical system characterized by satisfying the following conditional expression: (1) 0.61<f34 / fW<1.46 (2) 0.32<f4 / f3<0.96 (3) -0.0085<ΔPgF1+ΔPgF2<0.0070 f34: a composite focal length of the third lens group G3 to the fourth lens group G4, where f34=1 / (Σ(1 / fn)), n=3 to 4. fn is the focal length of the nth lens group. fW: focal length at the wide-angle end of the variable magnification optical system f4: focal length of the fourth lens group G4 f3: focal length of the third lens group G3 ΔPgF1: anomalous dispersion of the negative lens L3n arranged closest to the image in the third lens group G3, where ΔPgF1=PgF1-0.64833+0.00180×νd1. PgF1 is the partial dispersion ratio for the g-line and F-line of the negative lens L3n arranged closest to the image in the third lens group G3. νd1 is the Abbe number for the d-line of the negative lens L3n arranged closest to the image in the third lens group G3. ΔPgF2: anomalous dispersion of the negative lens L4n located closest to the object in the fourth lens group G4, where ΔPgF2=PgF2-0.64833+0.00180×νd2. PgF2 is the partial dispersion ratio for the g-line and F-line of the negative lens L4n located closest to the object in the fourth lens group G4. νd2 is the Abbe number for the d-line of the negative lens L4n located closest to the object in the fourth lens group G4.

2. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (4) 0.13<|f13| / f4L<1.25 f13: a composite focal length of the first lens group G1 to the third lens group G3, where f13=1 / (Σ(1 / fn)), n=1 to 3. fn is the focal length of the nth lens group. f4L: composite focal length of the fourth lens group G4 to the lens group arranged closest to the image (hereinafter referred to as the final lens group GL), where f4L=1 / (Σ(1 / fn)), n=4 to L. fn is the focal length of the nth lens group. fL is the focal length of the final lens group GL.

3. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (5) 1.12<m4 / m3<1.56 m4: the movement amount of the fourth lens group G4 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is positive) m3: the movement amount of the third lens group G3 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is positive)

4. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (6) 1.17<|f5| / f4<2.89 f5: focal length of the fifth lens group G5 f4: focal length of the fourth lens group G4

5. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (7) 0.83<m5 / m4<1.24 m5: the movement amount of the fifth lens group G5 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is positive) m4: the movement amount of the fourth lens group G4 when changing magnification from the wide-angle end to the telephoto end (movement toward the object side is positive)

6. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (8) 1.34<|f5L| / fW<4.25 f5L: composite focal length of the fifth lens group G5 to the lens group arranged closest to the image (hereinafter referred to as the final lens group GL), where f5L=1 / (Σ(1 / fn)), n=5 to L. fn is the focal length of the nth lens group. fL is the focal length of the lens group arranged closest to the image (hereinafter referred to as the final lens group GL). fW: focal length at the wide-angle end of the variable magnification optical system

7. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (9) 0.51<bfW / fW<1.85 bfW: back focus at the wide-angle end of the variable magnification optical system fW: focal length at the wide-angle end of the variable magnification optical system

8. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (10) 28.56<ωW<44.11 ωW: half angle of view at the wide-angle end of the variable magnification optical system, where ωW=arctan(Y / fW) / 2, and Y is the maximum image height at the wide-angle end of the variable magnification optical system. fW is the focal length at the wide-angle end of the variable magnification optical system.

9. 2. A variable magnification optical system according to claim 1, wherein the fourth lens group G4 moves toward the object side along the optical axis during focusing from the infinity end to the closest distance end.

10. 2. A variable magnification optical system according to claim 1, wherein the fifth lens group G5 moves along the optical axis toward the image side during focusing from the infinity end to the closest end.

11. 2. The variable magnification optical system according to claim 1, wherein the object-side lens surface of the negative lens L3n arranged closest to the image side in the third lens group G3 is in contact with air.

12. 2. The variable magnification optical system according to claim 1, wherein the object-side lens surface of the negative lens L4n arranged closest to the object side in the fourth lens group G4 is in contact with air.

13. 2. The variable magnification optical system according to claim 1, wherein the first lens group G1 includes at least one negative lens.

14. 2. The variable magnification optical system according to claim 1, further comprising an aperture stop S on the most object side of the third lens group G3, wherein the third lens group G3 and the aperture stop S move together during magnification variation.

15. 2. The variable magnification optical system according to claim 1, wherein the fifth lens group G5 has at least one positive lens.

16. 2. The variable magnification optical system according to claim 1, wherein the second lens group G2 is fixed relative to the image plane when the magnification is changed from the wide-angle end to the telephoto end.

17. 2. The variable magnification optical system according to claim 1, wherein the lens group arranged closest to the image side (hereinafter referred to as the final lens group GL) is fixed relative to the image plane when varying magnification from the wide-angle end to the telephoto end.

18. 2. The variable magnification optical system according to claim 1, wherein the third lens group G3 has a vibration-proof lens group with positive refractive power that is movable in a direction substantially perpendicular to the optical axis.

19. An imaging device comprising the variable magnification optical system according to any one of claims 1 to 18.

Images