Magnification optical system, optical instrument, and method for manufacturing a magnification optical system

Abstract

To provide a variable magnification optical system that minimizes aberration fluctuations during focusing. [Solution] The variable magnification optical system ZL includes a front lens group GA having a positive refractive power, a first intermediate lens group GM1 having a negative refractive power, a second intermediate lens group GM2 having a positive refractive power, and a successor lens group GR. When magnification is applied, the spacing between adjacent lens groups changes. The successor lens group GR includes a first focusing lens group GF1 positioned closest to the object and moving along the optical axis when focusing, and at least one other focusing lens group positioned closer to the image than the first focusing lens group GF1 and moving along the optical axis on a different trajectory than the first focusing lens group GF1 when focusing, satisfying the following condition. -0.37 <fFs / fFy<0.37 2.00

Description

[Technical Field]

[0001] The present invention relates to a variable magnification optical system, an optical instrument, and a method for manufacturing a variable magnification optical system. [Background technology]

[0002] Conventionally, variable magnification optical systems suitable for photographic cameras, electronic still cameras, video cameras, etc., have been proposed (see, for example, Patent Document 1). In such variable magnification optical systems, it is difficult to suppress aberration fluctuations during focusing. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-12243 [Overview of the Initiative]

[0004] The variable magnification optical system according to the present invention has a front lens group having positive refractive power, a first intermediate lens group having negative refractive power, a second intermediate lens group having positive refractive power, and a successor lens group, arranged in order from the object side along the optical axis, wherein the spacing between adjacent lens groups changes during magnification, and the successor lens group includes a first focusing lens group positioned closest to the object and moving along the optical axis when focusing, and at least one other focusing lens group positioned closer to the image than the first focusing lens group and moving along the optical axis on a different trajectory than the first focusing lens group when focusing, satisfying the following conditional expression. -0.37 <fFs / fFy<0.37 2.00 <f1 / fw<8.00 However, fFs: The focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the aforementioned successor lens group. fFy: The focal length of the focusing lens group with the weakest refractive power among the focusing lens groups included in the aforementioned successor lens group. f1: Focal length of the front lens group fw: Focal length of the variable magnification optical system at the wide-angle end.

[0005] The optical instrument according to the present invention is configured to include the above-described variable magnification optical system.

[0006] The present invention relates to a method for manufacturing a variable magnification optical system, comprising a front lens group having positive refractive power, a first intermediate lens group having negative refractive power, a second intermediate lens group having positive refractive power, and a subsequent lens group, arranged in order from the object side along the optical axis, wherein the spacing between adjacent lens groups changes during magnification, and the subsequent lens group includes a first focusing lens group positioned closest to the object and moving along the optical axis when focusing, and at least one other focusing lens group positioned closer to the image than the first focusing lens group and moving along the optical axis on a different trajectory than the first focusing lens group when focusing, and the lenses are arranged in the lens barrel to satisfy the following conditional expression. -0.37 <fFs / fFy<0.37 2.00 <f1 / fw<8.00 However, fFs: The focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the aforementioned successor lens group. fFy: The focal length of the focusing lens group with the weakest refractive power among the focusing lens groups included in the aforementioned successor lens group. f1: Focal length of the front lens group fw: Focal length of the variable magnification optical system at the wide-angle end. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows the lens configuration of the variable magnification optical system according to the first embodiment. [Figure 2] Figures 2(A) and 2(B) show the aberrations at infinity focus in the wide-angle and telephoto ends of the variable magnification optical system according to the first embodiment, respectively. [Figure 3] Figures 3(A) and 3(B) show the various aberrations when the variable magnification optical system according to the first embodiment is focused at close range in the wide-angle and telephoto ends, respectively. [Figure 4] This figure shows the lens configuration of the variable magnification optical system according to the second embodiment. [Figure 5] Figures 5(A) and 5(B) are aberration diagrams at infinity focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the second embodiment, respectively. [Figure 6] Figures 6(A) and 6(B) are aberration diagrams at close focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the second embodiment, respectively. [Figure 7] It is a diagram showing the lens configuration of the zoom optical system according to the third embodiment. [Figure 8] Figures 8(A) and 8(B) are aberration diagrams at infinity focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the third embodiment, respectively. [Figure 9] Figures 9(A) and 9(B) are aberration diagrams at close focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the third embodiment, respectively. [Figure 10] It is a diagram showing the lens configuration of the zoom optical system according to the fourth embodiment. [Figure 11] Figures 11(A) and 11(B) are aberration diagrams at infinity focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the fourth embodiment, respectively. [Figure 12] Figures 12(A) and 12(B) are aberration diagrams at close focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the fourth embodiment, respectively. [Figure 13] It is a diagram showing the lens configuration of the zoom optical system according to the fifth embodiment. [Figure 14] Figures 14(A) and 14(B) are aberration diagrams at infinity focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the fifth embodiment, respectively. [Figure 15] Figures 15(A) and 15(B) are aberration diagrams at close focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the fifth embodiment, respectively. [Figure 16] It is a diagram showing the lens configuration of the zoom optical system according to the sixth embodiment. [Figure 17]FIG. 17(A) and FIG. 17(B) are aberration diagrams at infinity focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the sixth embodiment, respectively. [Figure 18] FIG. 18(A) and FIG. 18(B) are aberration diagrams at close focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the sixth embodiment, respectively. [Figure 19] It is a diagram showing the lens configuration of the zoom optical system according to the seventh embodiment. [Figure 20] FIG. 20(A) and FIG. 20(B) are aberration diagrams at infinity focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the seventh embodiment, respectively. [Figure 21] FIG. 21(A) and FIG. 21(B) are aberration diagrams at close focus in the wide-angle end state and the telephoto end state of the zoom optical system according to the seventh embodiment, respectively. [Figure 22] It is a diagram showing the configuration of a camera equipped with the zoom optical system according to the present embodiment. [Figure 23] It is a flowchart showing a manufacturing method of the zoom optical system according to the present embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0009] ​​Light from the subject is focused by the variable magnification optical system ZL of the photographic lens 3 and reaches the image plane I of the image sensor 4. The light from the subject that reaches the image plane I is photoelectrically converted by the image sensor 4 and recorded as digital image data in memory (not shown). The digital image data recorded in memory can be displayed on the liquid crystal screen 5 according to the user's operation. This camera may be a mirrorless camera or a single-lens reflex type camera with a quick-return mirror. Also, the variable magnification optical system ZL shown in Figure 22 is a schematic representation of a variable magnification optical system provided in the photographic lens 3, and the lens configuration of the variable magnification optical system ZL is not limited to this configuration.

[0010] Next, a variable magnification optical system according to this embodiment will be described. As an example of a variable magnification optical system (zoom lens) ZL according to this embodiment, the variable magnification optical system ZL(1) is configured as shown in Figure 1, and comprises a front lens group GA having positive refractive power, a first intermediate lens group GM1 having negative refractive power, a second intermediate lens group GM2 having positive refractive power, and a successor lens group GR, all arranged in order from the object side along the optical axis. When magnification occurs, the spacing between adjacent lens groups changes. The successor lens group GR includes a first focusing lens group GF1 positioned closest to the object and moving along the optical axis when focusing, and at least one other focusing lens group positioned closer to the image than the first focusing lens group GF1 and moving along the optical axis on a different trajectory than the first focusing lens group GF1 when focusing.

[0011] Under the above configuration, the variable magnification optical system ZL according to this embodiment satisfies the following conditions (1) and (2). -0.37 <fFs / fFy<0.37 ···(1) 2.00 <f1 / fw<8.00 ···(2) However, fFs: The focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the subsequent lens group GR. fFy: The focal length of the focusing lens group with the weakest refractive power among the focusing lens groups included in the subsequent lens group GR. f1: Focal length of the front lens group GA fw: Focal length of the variable magnification optical system ZL at the wide-angle end.

[0012] According to this embodiment, it is possible to obtain a variable magnification optical system with minimal aberration fluctuations during focusing, and an optical instrument equipped with this variable magnification optical system. Furthermore, by having multiple focusing lens groups in the subsequent lens group GR, fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed without increasing the size of the focusing lens group. In addition, by changing the spacing between adjacent lens groups during magnification, aberration correction during magnification can be improved.

[0013] The variable magnification optical system ZL according to this embodiment may be the variable magnification optical system ZL(2) shown in Figure 4, the variable magnification optical system ZL(3) shown in Figure 7, or the variable magnification optical system ZL(4) shown in Figure 10. Furthermore, the variable magnification optical system ZL according to this embodiment may be the variable magnification optical system ZL(5) shown in Figure 13, the variable magnification optical system ZL(6) shown in Figure 16, or the variable magnification optical system ZL(7) shown in Figure 19.

[0014] Conditional equation (1) defines an appropriate relationship between the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the subsequent lens group GR and the focal length of the focusing lens group with the weakest refractive power among the focusing lens groups included in the subsequent lens group GR. By satisfying conditional equation (1), fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed.

[0015] If the corresponding value in conditional equation (1) exceeds the upper limit, the difference in refractive power between the focusing lens group with the strongest refractive power and the focusing lens group with the weakest refractive power becomes smaller, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the upper limit of conditional equation (1) to 0.35, 0.30, 0.28, 0.26, 0.20, 0.18, and further to 0.15, the effect of this embodiment can be made more reliable.

[0016] Even if the corresponding value in conditional equation (1) falls below the lower limit, the difference in refractive power between the focusing lens group with the strongest refractive power and the focusing lens group with the weakest refractive power becomes small, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional equation (1) to -0.35, -0.30, -0.25, -0.20, -1.50, -1.00, -0.50, -0.30, and further to -0.10, the effect of this embodiment can be made more reliable.

[0017] Condition (2) defines the appropriate relationship between the focal length of the front lens group GA and the focal length of the variable magnification optical system ZL at the wide-angle end. By satisfying condition (2), it is possible to suppress variations in various aberrations, including spherical aberration, during magnification without increasing the size of the lens barrel.

[0018] If the corresponding value in conditional equation (2) exceeds the upper limit, the refractive power of the front lens group GA weakens, resulting in a larger movement of the front lens group GA during magnification and thus a larger lens barrel. By setting the upper limit of conditional equation (2) to 7.80, 7.50, 7.40, 7.00, 6.50, 6.30, and further to 6.00, the effect of this embodiment can be made more reliable.

[0019] If the corresponding value in conditional equation (2) falls below the lower limit, the refractive power of the front lens group GA increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during magnification. By setting the lower limit of conditional equation (2) to 2.30, 2.50, 2.80, 3.00, 3.30, 3.50, and further to 3.80, the effect of this embodiment can be made more reliable.

[0020] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (3). -6.00 <fFs / fw<6.00 ···(3)

[0021] Condition (3) defines the appropriate relationship between the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the subsequent lens group GR, and the focal length of the variable magnification optical system ZL at the wide-angle end. By satisfying condition (3), fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed.

[0022] If the corresponding value in conditional equation (3) exceeds the upper limit, the difference in refractive power between the focusing lens group with the strongest refractive power and the focusing lens group with the weakest refractive power becomes smaller, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the upper limit of conditional equation (3) to 5.50, 5.00, 4.80, 4.50, 4.00, and further to 3.80, the effect of this embodiment can be made more reliable.

[0023] If the corresponding value in conditional equation (3) falls below the lower limit, the refractive power of the focusing lens group with the strongest refractive power becomes stronger, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional equation (3) to -5.50, -5.00, -4.50, -4.00, -3.50, -3.00, -2.50, -2.00, and further to -1.80, the effect of this embodiment can be made more reliable.

[0024] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (4). 4.30 <f1 / (-fM1w)<10.00 ···(4) However, fM1w: Focal length of the first intermediate lens group GM1 at the wide-angle end.

[0025] Conditional equation (4) defines the appropriate relationship between the focal length of the front lens group GA and the focal length of the first intermediate lens group GM1 at the wide-angle end. By satisfying conditional equation (4), fluctuations in various aberrations, including spherical aberration, during magnification can be suppressed.

[0026] If the corresponding value in conditional equation (4) exceeds the upper limit, the refractive power of the first intermediate lens group GM1 increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during magnification. By setting the upper limit of conditional equation (4) to 9.50, 9.00, 8.80, 8.50, 8.30, 8.00, and further to 7.80, the effect of this embodiment can be made more reliable.

[0027] If the corresponding value in conditional equation (4) falls below the lower limit, the refractive power of the front lens group GA increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during magnification. By setting the lower limit of conditional equation (4) to 4.50, 4.80, 5.00, and further to 5.40, the effects of this embodiment can be made more reliable.

[0028] In the variable magnification optical system ZL according to this embodiment, the second intermediate lens group GM2 preferably includes at least two lens groups having positive refractive power and satisfies the following condition (5). 1.50 <f1 / fM21<7.00 ···(5) However, fM21: The focal length of the lens group closest to the object among the lens groups included in the second intermediate lens group GM2.

[0029] Condition (5) defines the appropriate relationship between the focal length of the front lens group GA and the focal length of the lens group closest to the object among the lens groups included in the second intermediate lens group GM2. By satisfying condition (5), fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed.

[0030] If the corresponding value in conditional equation (5) exceeds the upper limit, the refractive power of the lens group closest to the object among the lens groups included in the second intermediate lens group GM2 becomes stronger, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the upper limit of conditional equation (5) to 6.80, 6.50, 6.30, 6.00, 5.80, 5.00, 4.50, 4.00, and further to 3.50, the effect of this embodiment can be made more reliable.

[0031] If the corresponding value in conditional equation (5) falls below the lower limit, the refractive power of the front lens group GA increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional equation (5) to 1.60, 1.80, 2.00, 2.10, and further to 2.20, the effect of this embodiment can be made more reliable.

[0032] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (6). 0.10 <BFw / fw<1.00 ···(6) However, BFw: Back focus of the variable magnification optical system ZL at the wide-angle end.

[0033] Conditional equation (6) defines the appropriate relationship between the back focus of the variable magnification optical system ZL at the wide-angle end and the focal length of the variable magnification optical system ZL at the wide-angle end. By satisfying conditional equation (6), various aberrations, including coma aberration, can be effectively corrected at the wide-angle end.

[0034] If the corresponding value in conditional equation (6) exceeds the upper limit, the back focus of the variable magnification optical system ZL at the wide-angle end becomes large relative to the focal length of the variable magnification optical system ZL at the wide-angle end, making it difficult to correct various aberrations, including coma aberration, at the wide-angle end. By setting the upper limit of conditional equation (6) to 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, and further to 0.60, the effect of this embodiment can be made more reliable.

[0035] If the corresponding value in conditional equation (6) falls below the lower limit, the back focus of the variable magnification optical system ZL at the wide-angle end becomes small relative to the focal length of the variable magnification optical system ZL at the wide-angle end, making it difficult to correct aberrations such as coma at the wide-angle end. Furthermore, it becomes difficult to arrange the mechanical components of the lens barrel. By setting the lower limit of conditional equation (6) to 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, and further to 0.43, the effects of this embodiment can be made more reliable.

[0036] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (7). 0.20 < |fFs| / f1 < 2.00 ... (7)

[0037] Condition (7) defines the appropriate relationship between the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the subsequent lens group GR and the focal length of the front lens group GA. By satisfying condition (7), it is possible to suppress fluctuations in various aberrations, including spherical aberration, during focusing without increasing the size of the lens barrel. Furthermore, it is possible to suppress fluctuations in various aberrations, including spherical aberration, during magnification without increasing the size of the lens barrel.

[0038] If the corresponding value in conditional equation (7) exceeds the upper limit, the refractive power of the focusing lens group weakens, resulting in a larger movement of the focusing lens group during focusing and a larger lens barrel. Furthermore, the refractive power of the front lens group GA becomes stronger, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during magnification. By setting the upper limit of conditional equation (7) to 1.80, 1.50, 1.30, 1.00, 0.85, 0.70, 0.65, 0.60, and further to 0.58, the effects of this embodiment can be made more reliable.

[0039] If the corresponding value in conditional equation (7) falls below the lower limit, the refractive power of the focusing lens group increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. Furthermore, the refractive power of the front lens group GA decreases, increasing the amount of movement of the front lens group GA during magnification, resulting in a larger lens barrel. By setting the lower limit of conditional equation (7) to 0.22, 0.24, 0.25, and further to 0.26, the effects of this embodiment can be made more reliable.

[0040] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (8). 1.50<|fFs| / (-fM1w)<5.00 (8) However, fM1w: Focal length of the first intermediate lens group GM1 at the wide-angle end.

[0041] Conditional equation (8) defines the appropriate relationship between the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the subsequent lens group GR, and the focal length of the first intermediate lens group GM1 at the wide-angle end. By satisfying conditional equation (8), fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed. Furthermore, various aberrations, including coma aberration, at the wide-angle end can be well corrected.

[0042] If the corresponding value in conditional equation (8) exceeds the upper limit, the refractive power of the first intermediate lens group GM1 at the wide-angle end becomes stronger, making it difficult to correct aberrations such as coma at the wide-angle end. By setting the upper limit of conditional equation (8) to 4.85, 4.70, 4.50, 4.35, 4.25, 3.85, 3.50, 3.00, and further to 2.50, the effect of this embodiment can be made more reliable.

[0043] If the corresponding value in conditional equation (8) falls below the lower limit, the refractive power of the focusing lens group increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional equation (8) to 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, and further to 1.83, the effect of this embodiment can be made more reliable.

[0044] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (9). 0.90<|fFs| / fM2w<4.00 (9) However, fM2w: Focal length of the second intermediate lens group GM2 at the wide-angle end.

[0045] Conditional equation (9) defines the appropriate relationship between the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the subsequent lens group GR, and the focal length of the second intermediate lens group GM2 at the wide-angle end. By satisfying conditional equation (9), fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed. Furthermore, various aberrations, including coma aberration, at the wide-angle end can be well corrected.

[0046] If the corresponding value in conditional equation (9) exceeds the upper limit, the refractive power of the second intermediate lens group GM2 at the wide-angle end becomes stronger, making it difficult to correct aberrations such as coma at the wide-angle end. By setting the upper limit of conditional equation (9) to 3.80, 3.50, 3.30, 3.00, 2.80, 2.60, 2.00, 1.80, and further to 1.50, the effect of this embodiment can be made more reliable.

[0047] If the corresponding value in conditional equation (9) falls below the lower limit, the refractive power of the focusing lens group increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional equation (9) to 0.95, 0.98, 1.00, 1.03, and further to 1.05, the effect of this embodiment can be made more reliable.

[0048] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (10). 0.20 <f1 / (-fRw)<5.00 ···(10) However, fRw: focal length of the subsequent lens group GR at the wide-angle end.

[0049] Conditional equation (10) defines the appropriate relationship between the focal length of the front lens group GA and the focal length of the subsequent lens group GR at the wide-angle end. By satisfying conditional equation (10), various aberrations, including coma aberration at the wide-angle end, can be effectively corrected without increasing the size of the lens barrel.

[0050] If the corresponding value in conditional equation (10) exceeds the upper limit, the refractive power of the subsequent lens group GR becomes stronger at the wide-angle end, making it difficult to correct aberrations such as coma at the wide-angle end. Also, the refractive power of the front lens group GA becomes weaker, increasing the amount of movement of the front lens group GA during magnification, resulting in a larger lens barrel. By setting the upper limit of conditional equation (10) to 4.50, 4.00, 3.80, 3.50, 3.30, 3.00, 2.80, and further to 2.50, the effects of this embodiment can be made more reliable.

[0051] If the corresponding value in conditional equation (10) falls below the lower limit, the refractive power of the subsequent lens group GR weakens at the wide-angle end, making it difficult to correct aberrations such as coma at the wide-angle end. By setting the lower limit of conditional equation (10) to 0.40, 0.50, 0.60, 0.65, 0.68, and further to 0.70, the effect of this embodiment can be made more reliable.

[0052] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (11). 0.10 <MTF1 / MTF2<3.00 ···(11) However, MTF1: The absolute value of the amount of movement of the first focusing lens group GF1 when focusing from an object at infinity to a nearby object at the telephoto end. MTF2: The absolute value of the movement of the focusing lens group closest to the first focusing lens group GF1 among the other focusing lens groups when focusing from an object at infinity to a nearby object at the telephoto end.

[0053] Conditional equation (11) defines an appropriate relationship between the amount of movement of the first focusing lens group GF1 when focusing from an object at infinity to a nearby object at the telephoto end, and the amount of movement of the focusing lens group closest to the first focusing lens group GF1. By satisfying conditional equation (11), fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a nearby object at the telephoto end can be suppressed.

[0054] If the corresponding value in conditional equation (11) exceeds the upper limit, the amount of movement of the first focusing lens group GF1 becomes too large when focusing from an object at infinity to a nearby object at the telephoto end, making it difficult to suppress fluctuations in various aberrations, including spherical aberration. By setting the upper limit of conditional equation (11) to 2.80, 2.50, 2.30, 2.00, 1.80, 1.65, and further to 1.50, the effect of this embodiment can be made more reliable.

[0055] If the corresponding value in conditional equation (11) falls below the lower limit, the amount of movement of the focusing lens group closest to the first focusing lens group GF1 becomes too large when focusing from an object at infinity to a nearby object at the telephoto end, making it difficult to suppress fluctuations in various aberrations, including spherical aberration. By setting the lower limit of conditional equation (11) to 0.13, 0.15, 0.18, 0.20, 0.23, and further to 0.25, the effect of this embodiment can be made more reliable.

[0056] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (12). 0.10<βF1w / βF2w<3.00 (12) However, βF1w: Among the focusing lens groups included in the subsequent lens group GR, the focusing lens group located closer to the object than the focusing lens group closest to the image is the combined horizontal magnification when focusing on an object at infinity in the wide-angle end state. βF2w: Among the focusing lens groups included in the subsequent GR lens group, the focusing lens group closest to the image sensor is the horizontal magnification when focusing on an object at infinity at the wide-angle end.

[0057] Conditional equation (12) defines an appropriate relationship between the lateral magnification when focusing on an object at infinity at the wide-angle end of the focusing lens group closest to the image among the focusing lens groups included in the subsequent lens group GR, and the combined lateral magnification when focusing on an object at infinity at the wide-angle end of the focusing lens group located closer to the object than the focusing lens group closest to the image. By satisfying conditional equation (12), fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a nearby object at the wide-angle end can be suppressed.

[0058] If the corresponding value in conditional equation (12) exceeds the upper limit, the combined horizontal magnification when focusing on an object at infinity in the wide-angle end state of the focusing lens group located closer to the object than the focusing lens group closest to the image becomes too large. As a result, it becomes difficult to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a nearby object in the wide-angle end state. By setting the upper limit of conditional equation (12) to 2.80, 2.50, 2.30, 2.00, 1.80, 1.50, 1.30, 1.00, and further to 0.90, the effect of this embodiment can be made more reliable.

[0059] If the corresponding value in conditional equation (12) falls below the lower limit, the lateral magnification when focusing on an object at infinity at the wide-angle end of the focusing lens group closest to the image becomes too large. As a result, it becomes difficult to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a nearby object at the wide-angle end. By setting the lower limit of conditional equation (12) to 0.20, 0.35, 0.50, 0.55, 0.58, and further to 0.60, the effect of this embodiment can be made more reliable.

[0060] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (13). 0.10<βF1t / βF2t<3.00 (13) However, for βF1t: Among the focusing lens groups included in the subsequent lens group GR, the focusing lens group located closer to the object than the focusing lens group closest to the image is the telephoto end state when focusing on an object at infinity, and the combined horizontal magnification is... βF2t: Among the focusing lens groups included in the subsequent lens group GR, the horizontal magnification when focusing on an object at infinity at the telephoto end of the focusing lens group closest to the image.

[0061] Conditional equation (13) defines an appropriate relationship between the lateral magnification when focusing on an object at infinity in the telephoto end state of the focusing lens group closest to the image among the focusing lens groups included in the subsequent lens group GR, and the combined lateral magnification when focusing on an object at infinity in the telephoto end state of the focusing lens group located closer to the object than the focusing lens group closest to the image. By satisfying conditional equation (13), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a nearby object in the telephoto end state.

[0062] If the corresponding value in conditional equation (13) exceeds the upper limit, the combined lateral magnification when focusing on an object at infinity in the telephoto end state of the focusing lens group located closer to the object than the focusing lens group closest to the image becomes too large. As a result, it becomes difficult to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a nearby object in the telephoto end state. By setting the upper limit of conditional equation (13) to 2.80, 2.50, 2.30, 2.00, 1.80, 1.50, 1.30, 1.00, and further to 0.80, the effect of this embodiment can be made more reliable.

[0063] If the corresponding value in conditional equation (13) falls below the lower limit, the lateral magnification when focusing on an object at infinity in the telephoto end state of the focusing lens group closest to the image becomes too large. As a result, it becomes difficult to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a nearby object in the telephoto end state. By setting the lower limit of conditional equation (13) to 0.13, 0.15, 0.18, 0.20, 0.23, and further to 0.25, the effect of this embodiment can be made more reliable.

[0064] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (14). 0.50 < βF1w < 2.60 ... (14) However, βF1w: Among the focusing lens groups included in the subsequent lens group GR, the focusing lens group located closer to the object than the focusing lens group closest to the image is the combined horizontal magnification when focusing on an object at infinity in the wide-angle end state.

[0065] Conditional equation (14) defines an appropriate range for the combined horizontal magnification when focusing on an object at infinity at the wide-angle end of the focusing lens group located closer to the object than the focusing lens group closest to the image, which is included in the subsequent lens group GR. By satisfying conditional equation (14), fluctuations in various aberrations, including spherical aberration and coma aberration, during focusing can be suppressed.

[0066] If the corresponding value in conditional equation (14) exceeds the upper limit, it becomes difficult to suppress variations in various aberrations during focusing. By setting the upper limit of conditional equation (14) to 2.58, 2.55, 2.00, 1.80, 1.50, 1.30, and further to 1.20, the effect of this embodiment can be made more reliable.

[0067] If the corresponding value in conditional equation (14) falls below the lower limit, it becomes difficult to suppress variations in various aberrations during focusing. By setting the lower limit of conditional equation (14) to 0.55, 0.60, 0.65, 0.70, and further to 0.73, the effect of this embodiment can be made more reliable.

[0068] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (15). 0.20 < βF2w < 1.80 ... (15) However, for βF2w: the horizontal magnification when focusing on an object at infinity in the wide-angle end state of the focusing lens group closest to the image in the subsequent lens group GR.

[0069] Conditional equation (15) defines an appropriate range for the horizontal magnification when focusing on an object at infinity at the wide-angle end of the focusing lens group closest to the image sensor among the focusing lens groups included in the subsequent lens group GR. By satisfying conditional equation (15), fluctuations in various aberrations, including spherical aberration and coma aberration, during focusing can be suppressed.

[0070] If the corresponding value in conditional equation (15) exceeds the upper limit, it becomes difficult to suppress variations in various aberrations during focusing. By setting the upper limit of conditional equation (15) to 1.78, 1.75, 1.73, 1.70, 1.68, and further to 1.60, the effect of this embodiment can be made more reliable.

[0071] If the corresponding value in conditional equation (15) falls below the lower limit, it becomes difficult to suppress variations in aberrations during focusing. By setting the lower limit of conditional equation (15) to 0.23, 0.25, and further to 0.28, the effect of this embodiment can be made more reliable.

[0072] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (16). {βF1w+(1 / βF1w)} -2 ≤0.25 ···(16) However, βF1w: Among the focusing lens groups included in the subsequent lens group GR, the focusing lens group located closer to the object than the focusing lens group closest to the image is the combined horizontal magnification when focusing on an object at infinity in the wide-angle end state.

[0073] Conditional equation (16) defines an appropriate range for the composite horizontal magnification when focusing on an object at infinity at the wide-angle end of the focusing lens group located closer to the object than the focusing lens group closest to the image, which is included in the subsequent lens group GR. By satisfying conditional equation (16), fluctuations in various aberrations, including spherical aberration and coma aberration, during focusing can be suppressed. If the corresponding value of conditional equation (16) exceeds the upper limit, it becomes difficult to suppress fluctuations in various aberrations during focusing.

[0074] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (17). {βF2w+(1 / βF2w)} -2 ≤0.25 ···(17) However, for βF2w: the horizontal magnification when focusing on an object at infinity in the wide-angle end state of the focusing lens group closest to the image in the subsequent lens group GR.

[0075] Conditional equation (17) defines an appropriate range for the horizontal magnification when focusing on an object at infinity at the wide-angle end of the focusing lens group closest to the image sensor among the focusing lens groups included in the subsequent lens group GR. By satisfying conditional equation (17), fluctuations in various aberrations, including spherical aberration and coma aberration, during focusing can be suppressed. If the corresponding value of conditional equation (17) exceeds the upper limit, it becomes difficult to suppress fluctuations in various aberrations during focusing.

[0076] In the variable magnification optical system ZL according to this embodiment, it is desirable that the subsequent lens group GR includes at least one lens group positioned closer to the image than the image-side focusing lens group among the focusing lens groups included in the subsequent lens group GR. This effectively suppresses fluctuations in various aberrations, including spherical aberration, during focusing.

[0077] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (18). 0.10<|fFs| / |fRF|<4.00 ···(18) However, fRF: The focal length of the lens group located adjacent to the image-side focusing lens group among the at least one lens group.

[0078] Conditional equation (18) defines an appropriate relationship between the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the subsequent lens group GR, and the focal length of the lens group positioned adjacent to the image-side focusing lens group on the image side. By satisfying conditional equation (18), fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed.

[0079] If the corresponding value in conditional equation (18) exceeds the upper limit, the refractive power of the lens group adjacent to the image-side focusing lens group becomes stronger, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the upper limit of conditional equation (18) to 3.80, 3.50, 3.30, 3.00, 2.80, 2.50, 2.30, 2.00, 1.50, 1.30, and further to 1.00, the effect of this embodiment can be made more reliable.

[0080] If the corresponding value in conditional equation (18) falls below the lower limit, the refractive power of the focusing lens group increases, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional equation (18) to 0.13, 0.15, and further to 0.18, the effect of this embodiment can be made more reliable.

[0081] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (19). 2ωw>75.0° ···(19) However, 2ωw: the entire field of view of the variable magnification optical system ZL at the wide-angle end.

[0082] Conditional equation (19) defines an appropriate range for the entire field of view of the variable magnification optical system ZL at the wide-angle end. Satisfying conditional equation (19) is preferable because it allows for the acquisition of a variable magnification optical system with a wide field of view. Setting the lower limit of conditional equation (19) to 78.0°, 80.0°, and further to 83.0° can make the effects of this embodiment more reliable.

[0083] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (20). ft / fw>3.50 ···(20) However, ft: focal length of the variable magnification optical system ZL at the telephoto end.

[0084] Conditional equation (20) defines an appropriate relationship between the focal length of the variable magnification optical system ZL at the telephoto end and the focal length of the variable magnification optical system ZL at the wide-angle end. Satisfying conditional equation (20) is preferable because it allows for the acquisition of a variable magnification optical system with a high magnification ratio. Setting the lower limit of conditional equation (20) to 3.80, 4.00, 4.20, and further to 4.40 can make the effects of this embodiment more reliable.

[0085] The variable magnification optical system ZL according to this embodiment preferably satisfies the following condition (21). 0.10 < (-fN) / fL < 1.00 ···(21) However, fN: the focal length of the second lens positioned from the image side in the variable magnification optical system ZL. fL: Focal length of the lens positioned closest to the image in the variable magnification optical system ZL.

[0086] Conditional equation (21) defines the appropriate relationship between the focal length of the second lens positioned from the image side in the variable magnification optical system ZL and the focal length of the lens positioned closest to the image side in the variable magnification optical system ZL. By satisfying conditional equation (21), various aberrations, including coma aberration at the wide-angle end, can be effectively corrected.

[0087] If the corresponding value in conditional equation (21) exceeds the upper limit, the refractive power of the lens positioned closest to the image in the variable magnification optical system ZL becomes stronger, making it difficult to correct various aberrations, including coma aberration, at the wide-angle end. By setting the upper limit of conditional equation (21) to 0.95, 0.90, 0.85, 0.83, 0.80, 0.78, 0.75, 0.73, and further to 0.70, the effect of this embodiment can be made more reliable.

[0088] If the corresponding value in conditional equation (21) falls below the lower limit, the refractive power of the second lens positioned from the image side in the variable magnification optical system ZL becomes stronger, making it difficult to correct various aberrations, including coma aberration, at the wide-angle end. By setting the lower limit of conditional equation (21) to 0.13, 0.15, and further to 0.18, the effect of this embodiment can be made more reliable.

[0089] Next, with reference to Figure 23, the manufacturing method of the variable magnification optical system ZL described above will be outlined. First, along the optical axis, in order from the object side, a front lens group GA having positive refractive power, a first intermediate lens group GM1 having negative refractive power, a second intermediate lens group GM2 having positive refractive power, and a successor lens group GR are arranged (step ST1). Next, the spacing between adjacent lens groups is configured to change during magnification (step ST2). Next, a first focusing lens group GF1 that moves along the optical axis when focusing is placed on the object side of the successor lens group GR, and at least one other focusing lens group that moves along the optical axis on a different trajectory than the first focusing lens group GF1 when focusing is placed on the image side of the successor lens group GR (step ST3). Then, each lens is arranged in the lens barrel so as to satisfy at least the above conditions (1) and (2) (step ST4). This manufacturing method makes it possible to produce a variable magnification optical system with minimal aberration variation during focusing. [Examples]

[0090] The variable magnification optical system ZL according to the embodiment of this present invention will be described below with reference to the drawings. Figures 1, 4, 7, 10, 13, 16, and 19 are cross-sectional views showing the configuration and refractive power distribution of the variable magnification optical system ZL{ZL(1) to ZL(7)} according to the first to seventh embodiments. In the cross-sectional views of the variable magnification optical system ZL(1) to ZL(7) according to the first to seventh embodiments, the direction of movement of the focusing group along the optical axis when focusing from infinity to a near-field object is indicated by an arrow along with the word "focus". In the cross-sectional views of the variable magnification optical system ZL(1) to ZL(7) according to the first to seventh embodiments, the direction of movement of each lens group along the optical axis when magnifying from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow.

[0091] In Figures 1, 4, 7, 10, 13, 16, and 19, each lens group is represented by a combination of code G and a number, and each lens is represented by a combination of code L and a number. In this case, in order to prevent the number and types of codes and numbers from becoming too large and complicated, each embodiment independently uses a combination of code and a number to represent the lens groups, etc. Therefore, even if the same combination of code and a number is used between embodiments, it does not mean that they have the same configuration.

[0092] Tables 1 to 7 are shown below. Table 1 shows the specifications for the first example, Table 2 for the second example, Table 3 for the third example, Table 4 for the fourth example, Table 5 for the fifth example, Table 6 for the sixth example, and Table 7 for the seventh example. In each example, the d-line (wavelength λ=587.6nm) and the g-line (wavelength λ=435.8nm) were selected as the targets for calculating the aberration characteristics.

[0093] In the [Overall Specifications] table, f is the focal length of the entire lens system, FNO is the F-number, 2ω is the angle of view (in degrees, where ω is half the angle of view), and Ymax is the maximum image height. TL is the distance from the frontmost lens element to the final lens element on the optical axis when focused at infinity, plus BF, and BF is the distance from the final lens element on the optical axis to the image plane I (back focus) when focused at infinity. These values ​​are shown for each magnification state at the wide-angle end (W) and telephoto end (T).

[0094] Furthermore, in the [Overall Specifications] table, fM1w indicates the focal length of the first intermediate lens group at the wide-angle end. fM2w indicates the focal length of the second intermediate lens group at the wide-angle end. MTF1 indicates the absolute value of the movement of the first focusing lens group when focusing from an infinity-far object to a near-field object at the telephoto end. MTF2 indicates the absolute value of the movement of the focusing lens group closest to the first focusing lens group among the other focusing lens groups when focusing from an infinity-far object to a near-field object at the telephoto end. βF1w indicates the combined lateral magnification at the wide-angle end when focusing on an infinity-far object for the focusing lens group located closer to the object than the image-side focusing lens group among the focusing lens groups included in the subsequent lens group. βF2w indicates the lateral magnification at the wide-angle end when focusing on an infinity-far object for the focusing lens group located closest to the image among the focusing lens groups included in the subsequent lens group. βF1t represents the combined lateral magnification when focusing on an object at infinity in the telephoto end state of the focusing lens group located closer to the object than the image-side focusing lens group among the focusing lens groups included in the subsequent lens group. βF2t represents the lateral magnification when focusing on an object at infinity in the telephoto end state of the focusing lens group located closest to the image among the focusing lens groups included in the subsequent lens group. fN represents the focal length of the second lens positioned from the image side in the variable magnification optical system. fL represents the focal length of the lens positioned closest to the image side in the variable magnification optical system. fRw represents the focal length of the subsequent lens group in the wide-angle end state.

[0095] In the [Lens Specifications] table, the surface number indicates the order of the optical surfaces from the object side along the direction of light propagation, R is the radius of curvature of each optical surface (a positive value is given for surfaces where the center of curvature is located on the image side), D is the interplanar spacing, which is the distance along the optical axis from each optical surface to the next optical surface (or image plane), nd is the refractive index of the optical component material with respect to the d line, and νd is the Abbe number with respect to the d line of the optical component material. "∞" for the radius of curvature indicates a plane or aperture, and (Aperture S) indicates the aperture diaphragm S. The refractive index of air nd = 1.00000 is omitted. If an optical surface is aspherical, an asterisk (*) is placed next to the surface number, and the radius of curvature R column shows the paraxial radius of curvature.

[0096] In the table of [Aspherical Data], for the aspherical surface shown in [Lens Specifications], the shape is expressed by the following formula (A). X(y) represents the distance along the optical axis (sag amount) from the tangent plane at the vertex of the aspherical surface to the position on the aspherical surface at height y, R represents the radius of curvature of the reference sphere (paraxial radius of curvature), κ represents the conic constant, and Ai represents the i-th order aspherical coefficient. "E-n" represents "×10 -n ". For example, 1.234E-05 = 1.234×10 -5 . Note that the second-order aspherical coefficient A2 is 0 and its description is omitted.

[0097] X(y)=(y 2 / R) / {1+(1-κ×y 2 / R 2 ) 1 / 2}+A4×y 4 +A6×y 6 +A8×y 8 +A10×y 10 …(A)

[0098] In the table of [Variable Interval Data], it shows the surface interval at surface number i where the surface interval is (Di) in the table of [Lens Specifications]. Also, the table of [Variable Interval Data] shows the surface interval in the infinity focus state and the surface interval in the close distance focus state.

[0099] In the table of [Lens Group Data], it shows the starting surface (the most object-side surface) and the focal length of each lens group.

[0100] Hereinafter, for all specification values, the published focal length f, radius of curvature R, surface interval D, and other lengths, etc. generally use "mm" when not otherwise specified. However, since the optical system can obtain the same optical performance even when proportionally enlarged or reduced, it is not limited to this.

[0101] The explanations of the tables up to here are common to all examples, and the overlapping explanations below are omitted.

[0102] (First Embodiment) The first embodiment will be described using Figures 1 to 3 and Table 1. Figure 1 is a diagram showing the lens configuration of the variable magnification optical system according to the first embodiment. The variable magnification optical system ZL(1) according to the first embodiment consists of 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, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power, all arranged in order from the object side along the optical axis. When magnifying from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move towards the object side along the optical axis, and the spacing between adjacent lens groups changes. The aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3. During magnification, the aperture diaphragm S moves along the optical axis together with the third lens group G3. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this is the same in all the following embodiments.

[0103] The first lens group G1 consists of a positive lens formed by the bonding of a negative meniscus lens L11 with its convex surface facing the object and a positive meniscus lens L12 with its convex surface facing the object, and a positive meniscus lens L13 with its convex surface facing the object, arranged in order from the object side along the optical axis.

[0104] The second lens group G2 consists of a negative meniscus lens L21 with its convex surface facing the object, arranged in order from the object side along the optical axis; a bonded positive lens formed by a negative meniscus lens L22 with its convex surface facing the object and a positive meniscus lens L23 with its convex surface facing the object; and a negative meniscus lens L24 with its concave surface facing the object. The negative meniscus lens L21 has an aspherical lens surface on the object side.

[0105] The third lens group G3 consists of a biconvex positive lens L31. The positive lens L31 has an aspherical surface on the object-facing side.

[0106] The fourth lens group G4 consists of a cemented positive lens formed by a negative meniscus lens L41 with a convex surface facing the object and a biconvex positive lens L42, arranged in order from the object side along the optical axis; a cemented positive lens formed by a biconvex positive lens L43 and a negative meniscus lens L44 with a concave surface facing the object; and a positive meniscus lens L45 with a concave surface facing the object. The lens surface of the positive meniscus lens L45 facing the object is aspherical.

[0107] The fifth lens group G5 consists of a positive meniscus lens L51 with its concave surface facing the object, and a negative lens L52 with a biconcave shape, arranged in order from the object side along the optical axis.

[0108] The sixth lens group G6 consists of a biconcave negative lens L61. The object-facing lens surface of the negative lens L61 is aspherical.

[0109] The seventh lens group G7 consists of a positive meniscus lens L71 with its convex surface facing the object. The image plane I is positioned on the image side of the seventh lens group G7.

[0110] In this embodiment, the first lens group G1 constitutes the front lens group GA, which has a positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1, which has a negative refractive power. The third lens group G3 and the fourth lens group G4 together constitute the second intermediate lens group GM2, which has a positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 together constitute the subsequent lens group GR, which has a negative refractive power as a whole. When focusing from an object at infinity to an object at a close distance, the fifth lens group G5 and the sixth lens group G6, which constitute the subsequent lens group GR, move toward the image side along the optical axis along different trajectories (amount of movement). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1, which is located closest to the object in the subsequent lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group located closer to the image than the first focusing lens group GF1.

[0111] Table 1 below lists the specifications of the variable magnification optical system according to the first embodiment.

[0112] (Table 1) [All Yuan] Multiplication ratio=4.74 fM1w=-17.655 fM2w=29.833 MTF1=0.344 MTF2=0.846 βF1w=1.071 βF2w=1.577 βF1t=1.111 βF2t=3.094 fN=-38.218 fL=129.310 fRw=-46.388 WMT f 24.700 84.962 116.999 FNO 4.07 4.07 4.07 2ω 85.22 27.40 20.32 Ymax 21.60 21.60 21.60 TL 128.45 162.37 178.87 BF 13.699 35.087 35.287 [レンズ Zhugen] Side number RD nd νd Object surface ∞ 1 164.9399 2.000 1.73800 32.26 2 56.4260 7.579 1.59319 67.90 3 329.6967 0.200 4 61.7045 5.273 1.81600 46.59 5 267.7629 (D5) 6* 242.3772 1.500 1.81600 46.59 7 16.6184 5.149 8 879.6675 1.000 1.58913 61.22 9 18.5708 4.233 1.95000 29.37 10 79.8132 2.602 11 -27.5163 1.000 1.77250 49.62 12 -60.4508 (D12) 13 ∞ 2.000 (Aperture S) 14* 33.9421 3.661 1.74310 49.44 15 -231.3985 (D15) 16 30.3875 1.000 1.88300 40.66 17 15.6459 6.192 1.49782 82.57 18 -453.7663 0.776 19 575.4338 5.622 1.51680 64.14 20 -18.7425 1.000 2.00069 25.46 21 -32.0090 1.264 22* -70.8783 5.056 1.55332 71.67 23 -21.6449 (D23) 24 -90.7732 3.558 1.94595 17.98 25 -39.1419 0.200 26 -156.1339 1.000 1.90366 31.27 27 79.8952 (D27) 28* -85.4924 1.500 1.81600 46.59 29 49.4815 (D29) 30 55.2902 3.197 1.90200 25.26 31 102.2388 BF Image plane ∞ [Aspherical Data] Surface 6 κ = 1.0000, A4 = 5.35995E-06, A6 = -8.27153E-09, A8 = 2.12565E-11, A10 = -2.60526E-14 Surface 14 κ = 1.0000, A4 = -7.33442E-06, A6 = 4.81859E-09, A8 = -4.26147E-11, A10 = -2.53196E-14 Surface 22 κ=1.0000,A4=-2.36052E-05,A6=6.01748E-09,A8=1.01789E-10,A10=1.24064E-13 Page 28 κ=1.0000,A4=-5.15978E-06,A6=-5.92439E-09,A8=4.45911E-12,A10=-6.10897E-15 [Variable interval data] Infinity focus state Close focus state WMTWMT D5 2.000 31.270 39.333 2.000 31.270 39.333 D12 17.917 3.226 2.000 17.917 3.226 2.000 D15 13.739 3.651 2.000 13.739 3.651 2.000 D23 6.364 2.978 2.000 6.466 3.278 2.344 D27 4.416 6.716 5.540 5.042 7.231 6.042 D29 3.757 12.879 26.147 3.029 12.064 25.302 [Lens group data] Group starting plane focal length G1 1 97.130 G2 6 -17.655 G3 14 40.069 G4 16 35.478 G5 24 -320.573 G6 28 -38.218 G7 30 129.310

[0113] Figure 2(A) is an aberration diagram of the variable magnification optical system according to the first embodiment when focused at infinity at the wide-angle end. Figure 2(B) is an aberration diagram of the variable magnification optical system according to the first embodiment when focused at infinity at the telephoto end. Figure 3(A) is an aberration diagram of the variable magnification optical system according to the first embodiment when focused at close range at the wide-angle end. Figure 3(B) is an aberration diagram of the variable magnification optical system according to the first embodiment when focused at close range at the telephoto end. In each aberration diagram when focused at infinity, FNO indicates the F number and Y indicates the image height. In each aberration diagram when focused at close range, NA indicates the numerical aperture and Y indicates the image height. Note that the spherical aberration diagram shows the F number or numerical aperture value corresponding to the maximum aperture, the astigmatism diagram and distortion diagram show the maximum image height, and the coma aberration diagram shows the values ​​of each image height. d represents the d-line (wavelength λ=587.6nm), and g represents the g-line (wavelength λ=435.8nm). In the astigmatism diagram, the solid line represents the sagittal image plane, and the dashed line represents the meridional image plane. In the aberration diagrams of the embodiments shown below, the same reference numerals as in this embodiment are used, and redundant explanations are omitted.

[0114] From the various aberration diagrams, it can be seen that the variable magnification optical system according to the first embodiment has excellent imaging performance, with aberrations being well corrected not only when focused at infinity but also when focused at close distances, from the wide-angle end to the telephoto end.

[0115] (Second example) The second embodiment will be described using Figures 4 to 6 and Table 2. Figure 4 is a diagram showing the lens configuration of the variable magnification optical system according to the second embodiment. The variable magnification optical system ZL(2) according to the second embodiment consists of 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, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power, all arranged in order from the object side along the optical axis. When magnifying from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move towards the object side along the optical axis, and the spacing between adjacent lens groups changes. The aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3. During magnification, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0116] The first lens group G1 consists of a positive lens formed by the bonding of a negative meniscus lens L11 with its convex surface facing the object and a positive meniscus lens L12 with its convex surface facing the object, and a positive meniscus lens L13 with its convex surface facing the object, arranged in order from the object side along the optical axis.

[0117] The second lens group G2 consists of a negative meniscus lens L21 with its convex surface facing the object, arranged in order from the object side along the optical axis; a bonded positive lens formed by a biconcave negative lens L22 and a biconvex positive lens L23; and a negative meniscus lens L24 with its concave surface facing the object. The negative meniscus lens L21 has an aspherical lens surface on the object side.

[0118] The third lens group G3 consists of a positive meniscus lens L31 with its convex surface facing the object, a biconvex positive lens L32, a bonded positive lens formed by a negative meniscus lens L33 with its convex surface facing the object and a biconvex positive lens L34, and a negative meniscus lens L35 with its concave surface facing the object.

[0119] The fourth lens group G4 consists of a bonded positive lens formed by a negative meniscus lens L41 with its convex surface facing the object and a positive lens L42 with a biconvex shape.

[0120] The fifth lens group G5 consists of a biconcave negative lens L51 arranged in order from the object side along the optical axis, and a bonded positive lens formed by a biconvex positive lens L52 and a negative meniscus lens L53 with its concave surface facing the object side. The negative meniscus lens L53 has an aspherical lens surface on the image side.

[0121] The sixth lens group G6 consists of a biconcave negative lens L61. The object-facing lens surface of the negative lens L61 is aspherical.

[0122] The seventh lens group G7 consists of a biconvex positive lens L71. The image plane I is positioned on the image side of the seventh lens group G7.

[0123] In this embodiment, the first lens group G1 constitutes the front lens group GA, which has a positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1, which has a negative refractive power. The third lens group G3 and the fourth lens group G4 together constitute the second intermediate lens group GM2, which has a positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 together constitute the subsequent lens group GR, which has a negative refractive power as a whole. When focusing from an object at infinity to an object at a close distance, the fifth lens group G5, which constitutes the subsequent lens group GR, moves toward the object along the optical axis, and the sixth lens group G6, which constitutes the subsequent lens group GR, moves toward the image along the optical axis. That is, the fifth lens group G5 corresponds to the first focusing lens group GF1, which is positioned closest to the object in the subsequent lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group positioned closer to the image than the first focusing lens group GF1.

[0124] Table 2 below lists the specifications of the variable magnification optical system according to the second embodiment.

[0125] (Table 2) [Overall Specifications] Multiplication ratio = 4.74 fM1w = -17.052 fM2w = 29.062 MTF1=0.279 MTF2=0.983 βF1w=1.045 βF2w=1.670 βF1t=1.038 βF2t=3.943 fN = -31.580 fL = 78.519 fRw = -61.009 WMT f 24.700 69.988 117.001 FNO 4.06 4.06 4.07 2ω 85.22 33.90 20.18 Ymax 21.60 21.60 21.60 TL 134.46 162.88 189.46 BF 11.455 31.812 35.779 [Lens Specifications] Face number RD nd νd Object plane ∞ 1 158.1192 2.000 1.73800 32.36 2 69.8101 6.421 1.59319 67.90 3 308.6050 0.200 4 66.9111 5.695 1.81600 46.59 5 207.3443 (D5) 6* 78.5237 1.500 1.81600 46.59 7 16.7218 5.684 8 -172.8187 1.000 1.80400 46.60 9 21.0165 4.905 1.90200 25.26 10 -209.4912 1.624 11 -33.2740 1.000 1.81600 46.59 12 -156.9568 (D12) 13 ∞ 2.000 (Aperture S) 14 37.1973 2.686 1.80518 25.45 15 73.4737 0.200 16 49.8914 3.509 1.59319 67.90 17 -304.2612 0.200 18 35.7712 1.000 1.84850 43.79 19 16.8712 7.999 1.59319 67.90 20 -57.2564 1.355 21 -36.5767 1.000 2.00069 25.46 22 -90.8325 (D22) 23 39.2071 1.000 2.00069 25.46 24 25.6545 6.685 1.59319 67.90 25 -38.5079 (D25) 26 -38.3881 1.000 1.94595 17.98 27 96.5319 0.415 28 37.3704 7.406 1.89286 20.36 29 -30.3636 1.000 1.68893 31.16 30* -185.8364 (D30) 31* -42.4996 1.500 1.81600 46.59 32 66.5016 (D32) 33 148.1143 4.377 1.89286 20.36 34 -131.2552 BF Image plane ∞ [Aspherical surface] Page 6 κ=1.0000,A4=1.23369E-06,A6=-3.23247E-09,A8=-1.36560E-12,A10=3.42111E-15 Page 30 κ=1.0000,A4=2.14045E-05,A6=-7.56199E-10,A8=-2.61800E-11,A10=1.98882E-13 Page 31 κ=1.0000,A4=-3.01641E-06,A6=-1.16781E-08,A8=-5.08849E-11,A10=3.00363E-13 [Variable interval data] Infinity focus state Close focus state WMTWMT D5 2.000 26.048 41.130 2.000 26.048 41.130 D12 21.130 5.163 2.000 21.130 5.163 2.000 D22 12.345 4.345 2.000 12.345 4.345 2.000 D25 2.023 7.035 9.889 2.000 6.858 9.610 D30 7.665 6.668 3.602 8.357 7.660 4.865 D32 4.476 8.453 21.695 3.807 7.637 20.712 [Lens group data] Group starting plane focal length G1 1 111.149 G2 6 -17.052 G3 14 34.545 G4 23 40.961 G5 26 915.545 G6 31 -31.580 G7 33 78.519

[0126] Figure 5(A) shows the aberrations of the variable magnification optical system according to the second embodiment when focused at infinity at the wide-angle end. Figure 5(B) shows the aberrations of the variable magnification optical system according to the second embodiment when focused at infinity at the telephoto end. Figure 6(A) shows the aberrations of the variable magnification optical system according to the second embodiment when focused at close range at the wide-angle end. Figure 6(B) shows the aberrations of the variable magnification optical system according to the second embodiment when focused at close range at the telephoto end. From each aberration diagram, it can be seen that the variable magnification optical system according to the second embodiment has excellent imaging performance, with aberrations well corrected from the wide-angle end to the telephoto end, not only when focused at infinity but also when focused at close range.

[0127] (Third embodiment) The third embodiment will be described using Figures 7 to 9 and Table 3. Figure 7 is a diagram showing the lens configuration of the variable magnification optical system according to the third embodiment. The variable magnification optical system ZL(3) according to the third embodiment consists of 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, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power, all arranged in order from the object side along the optical axis. When magnifying from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move towards the object side along the optical axis, and the spacing between adjacent lens groups changes. The aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3. During magnification, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0128] The first lens group G1 consists of a bonded positive lens formed by a plano-concave negative lens L11 with its plane facing the object and a biconvex positive lens L12, and a positive meniscus lens L13 with its convex surface facing the object, arranged in order from the object side along the optical axis.

[0129] The second lens group G2 consists of a negative meniscus lens L21 with its convex surface facing the object, arranged in order from the object side along the optical axis; a bonded positive lens formed by a biconcave negative lens L22 and a biconvex positive lens L23; and a plano-concave negative lens L24 with its plane facing the image side. The negative meniscus lens L21 has an aspherical lens surface on the object side.

[0130] The third lens group G3 consists of a positive meniscus lens L31 with its convex surface facing the object, a biconvex positive lens L32, and a negative meniscus lens L33 with its concave surface facing the object, all arranged in order from the object side along the optical axis. The positive meniscus lens L31 has an aspherical lens surface on the object side.

[0131] The fourth lens group G4 consists of a biconvex positive lens L41 arranged in order from the object side along the optical axis, and a bonded positive lens formed by a negative meniscus lens L42 with its convex surface facing the object side and a biconvex positive lens L43.

[0132] The fifth lens group G5 consists of a negative meniscus lens L51 with its concave surface facing the object, and a positive lens L52 with a biconvex shape, arranged in order from the object side along the optical axis.

[0133] The sixth lens group G6 consists of a positive meniscus lens L61 with its concave surface facing the object. The positive meniscus lens L61 has an aspherical lens surface on the image side.

[0134] The seventh lens group G7 consists of a biconcave negative lens L71 and a positive meniscus lens L72 with its convex side facing the object, arranged in order from the object side along the optical axis. The image plane I is positioned on the image side of the seventh lens group G7.

[0135] In this embodiment, the first lens group G1 constitutes the front lens group GA, which has positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1, which has negative refractive power. The third lens group G3 and the fourth lens group G4 together constitute the second intermediate lens group GM2, which has positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 together constitute the subsequent lens group GR, which has negative refractive power as a whole. When focusing from an object at infinity to an object at a close distance, the fifth lens group G5 and the sixth lens group G6, which constitute the subsequent lens group GR, move toward the object along the optical axis with different trajectories (amount of movement). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1, which is located closest to the object in the subsequent lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group located closer to the image than the first focusing lens group GF1.

[0136] Table 3 below lists the specifications of the variable magnification optical system according to the third embodiment.

[0137] (Table 3) [Overall Specifications] Multiplication ratio = 4.56 fM1w = -21.004 fM2w = 33.500 MTF1 = 1.413 MTF2 = 0.980 βF1w=0.770 βF2w=0.954 βF1t=0.658 βF2t=0.946 fN = -29.642 fL = 97.753 fRw = -158.485 WMT f 22.600 70.008 103.000 FNO 4.08 4.08 4.08 2ω 91.54 32.98 22.38 Ymax 21.60 21.60 21.60 TL 139.45 164.17 199.46 BF 11.455 38.439 39.811 [Lens Specifications] Face number RD nd νd Object plane ∞ 1 ∞ 2.000 1.84666 23.80 2 205.3318 6.252 1.59319 67.90 3 -265.8961 0.200 4 76.0378 4.794 1.77250 49.62 5 155.1941 (D5) 6* 118.3890 1.500 1.74389 49.53 7 19.9637 7.065 8 -66.8860 1.000 1.59319 67.90 9 24.3441 6.322 1.68893 31.16 10 -44.9916 0.573 11 -35.2853 1.000 1.81600 46.59 12 ∞ (D12) 13 ∞ 2.000 (Aperture S) 14* 53.1253 2.930 1.69343 53.30 15 3836.4092 0.200 16 51.4447 4.772 1.59319 67.90 17 -49.9261 2.897 18 -36.2339 1.000 1.83481 42.73 19 -1562.5863 (D19) 20 41.8346 4.903 1.59319 67.90 21 -69.8682 0.200 22 94.4862 1.000 1.81600 46.59 23 19.6322 7.665 1.49782 82.57 24 -56.1775 (D24) 25 -29.1264 1.000 1.90200 25.26 26 -57.1334 2.304 27 93.4868 5.411 1.80400 46.60 28 -48.3174 (D28) 29 -85.5900 1.691 1.77387 47.25 30* -67.1935 (D30) 31 -56.6426 1.000 1.83481 42.73 32 44.2945 2.378 33 64.6533 3.175 1.94595 17.98 34 209.7975 BF Image plane ∞ [Aspherical surface] Page 6 κ=1.0000,A4=2.28381E-06,A6=-1.46352E-09,A8=-1.25256E-12,A10=5.36019E-15 Page 14 κ = 1.0000, A4 = -2.87497E-06, A6 = 1.67465E-09, A8 = -4.38683E-12, A10 = -1.60647E-15 Page 30 κ = 1.0000, A4 = 9.04034E-06, A6 = 8.01114E-10, A8 = 6.16585E-12, A10 = -1.63681E-14 [Variable interval data] Infinity focus state, close focus state W M T W M T D5 2.000 16.912 51.168 2.000 16.912 51.168 D12 23.202 2.589 2.000 23.202 2.589 2.000 D19 10.189 2.436 2.000 10.189 2.436 2.000 D24 5.554 14.413 18.443 4.619 13.500 17.030 D28 2.044 8.464 8.285 2.513 8.681 8.718 D30 9.778 5.681 2.517 10.245 6.377 3.497 [Lens group data] Group, starting surface, focal length G1 1 157.131 G2 6 -22.004 G3 14 59.544 G4 20 43.565 G5 25 84.112 G6 29 388.390 G7 31 -43.760

[0138] Figure 8(A) is a diagram of aberrations when the variable magnification optical system according to the third embodiment is focused at infinity at the wide-angle end. Figure 8(B) is a diagram of aberrations when the variable magnification optical system according to the third embodiment is focused at infinity at the telephoto end. Figure 9(A) is a diagram of aberrations when the variable magnification optical system according to the third embodiment is focused at close range at the wide-angle end. Figure 9(B) is a diagram of aberrations when the variable magnification optical system according to the third embodiment is focused at close range at the telephoto end. From each of the aberration diagrams, it can be seen that the variable magnification optical system according to the third embodiment has excellent imaging performance, with aberrations well corrected from the wide-angle end to the telephoto end, not only when focused at infinity but also when focused at close range.

[0139] (Fourth embodiment) The fourth embodiment will be explained using Figures 10 to 12 and Table 4. Figure 10 is a diagram showing the lens configuration of the variable magnification optical system according to the fourth embodiment. The variable magnification optical system ZL(4) according to the fourth embodiment consists of 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, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power, all arranged in order from the object side along the optical axis. When magnifying from the wide-angle end state (W) to the telephoto end state (T), the first to sixth lens groups G1 to G6 move towards the object side along the optical axis, and the seventh lens group G7 moves towards the object side along the optical axis before moving towards the image side, changing the spacing between adjacent lens groups. The aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3. During magnification, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0140] The first lens group G1 consists of a positive lens formed by the bonding of a negative meniscus lens L11 with its convex surface facing the object and a positive meniscus lens L12 with its convex surface facing the object, and a positive meniscus lens L13 with its convex surface facing the object, arranged in order from the object side along the optical axis.

[0141] The second lens group G2 consists of a negative meniscus lens L21 with its convex surface facing the object, arranged in order from the object side along the optical axis; a bonded positive lens formed by a negative meniscus lens L22 with its convex surface facing the object and a positive meniscus lens L23 with its convex surface facing the object; and a biconcave negative lens L24. The negative meniscus lens L21 has an aspherical lens surface on the object side.

[0142] The third lens group G3 consists of a positive meniscus lens L31 with its convex surface facing the object, and a positive meniscus lens L32 with its convex surface facing the object. The lens surface of the positive meniscus lens L31 facing the object is aspherical.

[0143] The fourth lens group G4 consists of a cemented positive lens formed by a negative meniscus lens L41 with a convex surface facing the object and a biconvex positive lens L42, arranged in order from the object side along the optical axis; a cemented negative lens formed by a biconvex positive lens L43 and a negative meniscus lens L44 with a concave surface facing the object; and a positive meniscus lens L45 with a concave surface facing the object. The lens surface of the positive meniscus lens L45 facing the object is aspherical.

[0144] The fifth lens group G5 consists of a biconvex positive lens L51 and a biconcave negative lens L52, which are arranged in order from the object side along the optical axis.

[0145] The sixth lens group G6 consists of a biconcave negative lens L61. The object-facing lens surface of the negative lens L61 is aspherical.

[0146] The seventh lens group G7 consists of a positive meniscus lens L71 with its convex surface facing the object. The image plane I is positioned on the image side of the seventh lens group G7.

[0147] In this embodiment, the first lens group G1 constitutes the front lens group GA, which has a positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1, which has a negative refractive power. The third lens group G3 and the fourth lens group G4 together constitute the second intermediate lens group GM2, which has a positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 together constitute the subsequent lens group GR, which has a negative refractive power as a whole. When focusing from an object at infinity to an object at a close distance, the fifth lens group G5 and the sixth lens group G6, which constitute the subsequent lens group GR, move toward the image side along the optical axis along different trajectories (amount of movement). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1, which is located closest to the object in the subsequent lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group located closer to the image than the first focusing lens group GF1.

[0148] Table 4 below lists the specifications of the variable magnification optical system according to the fourth embodiment.

[0149] (Table 4) [Overall Specifications] Multiplication ratio = 7.85 fM1w = -17.910 fM2w = 29.807 MTF1=0.411 MTF2=0.952 βF1w=1.005 βF2w=1.561 βF1t=1.019 βF2t=3.610 fN = -35.994 fL = 170.661 fRw = -44.489 WMT f 24.700 104.937 194.000 FNO 4.02 5.60 6.42 2ω 85.20 22.32 12.46 Ymax 21.60 21.60 21.60 TL 130.17 173.77 204.45 BF 12.455 42.064 38.864 [Lens Specifications] Face number RD nd νd Object plane ∞ 1 143.1350 2.000 1.73800 32.33 2 54.4612 7.561 1.59319 67.90 3 300.0372 0.200 4 69.5685 5.062 1.77250 49.62 5 409.0849 (D5) 6* 350.7774 1.500 1.88202 37.22 7 18.4546 4.874 8 680.4222 1.000 1.49782 82.57 9 19.1843 4.572 1.85000 27.03 10 106.5036 1.893 11 -45.6629 1.000 1.77250 49.62 12 1027.7309 (D12) 13 ∞ 2.000 (Aperture S) 14* 29.9260 2.529 1.67798 54.89 15 104.6758 0.200 16 37.9415 1.902 1.80809 22.74 17 50.9616 (D17) 18 24.4645 1.758 1.90265 35.77 19 14.5575 6.153 1.49782 82.57 20 -102.7198 0.611 21 1507.9760 4.275 1.51680 64.13 22 -24.0428 1.000 2.00069 25.46 23 -87.8436 0.355 24* -128.1468 4.545 1.55332 71.68 25 -20.7344 (D25) 26 738.8688 4.696 1.80809 22.74 27 -32.2613 0.200 28 -47.0892 1.000 1.81600 46.59 29 81.3412 (D29) 30* -59.9653 1.500 1.77387 47.25 31 52.5852 (D31) 32 51.1837 3.083 1.68893 31.16 33 88.4174 BF Image plane ∞ [Aspherical surface] Page 6 κ=1.0000,A4=3.16658E-06,A6=-5.96049E-09,A8=1.61416E-11,A10=-2.62532E-14 Page 14 κ=1.0000,A4=-7.64081E-06,A6=-1.02540E-08,A8=8.93373E-11,A10=-6.51264E-13 Page 24 κ=1.0000,A4=-3.12885E-05,A6=3.71787E-08,A8=-1.70544E-10,A10=1.40544E-12 Page 30 κ=1.0000,A4=-5.46471E-06,A6=-2.65649E-0,A8=1.47492E-10,A10=-2.98216E-13 [Can change the interval データ] Infinity focus state Close focus state WMTWMT D5 2.010 35.817 51.220 2.010 35.817 51.220 D12 21.188 4.932 2.030 21.188 4.932 2.030 D17 13.539 4.497 2.000 13.539 4.497 2.000 D25 7.124 3.715 2.000 7.265 4.018 2.411 D29 4.593 6.548 4.486 5.167 7.059 5.027 D31 3.794 10.730 38.386 3.078 9.916 37.434 [Lens group data] Group starting surface Focal length G1 1 103.273 G2 6 -17.910 G3 14 44.938 G4 18 37.783 G5 26 -980.001 G6 30 -35.994 G7 32 170.661

[0150] FIG. 11(A) is a diagram of various aberrations at infinity focus in the wide-angle end state of the zoom optical system according to the fourth embodiment. FIG. 11(B) is a diagram of various aberrations at infinity focus in the telephoto end state of the zoom optical system according to the fourth embodiment. FIG. 12(A) is a diagram of various aberrations at close focus in the wide-angle end state of the zoom optical system according to the fourth embodiment. FIG. 12(B) is a diagram of various aberrations at close focus in the telephoto end state of the zoom optical system according to the fourth embodiment. From each diagram of various aberrations, it can be seen that the zoom optical system according to the fourth embodiment has excellent imaging performance with various aberrations well corrected from the wide-angle end state to the telephoto end state not only at infinity focus but also at close focus.

[0151] (The fifth embodiment) The fifth embodiment will be described with reference to FIGS. 13 to 15 and Table 5. FIG. 13 is a diagram showing the lens configuration of the zoom optical system according to the fifth embodiment. The zoom optical system ZL(5) according to the fifth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a positive refractive power, a sixth lens group G6 having a negative refractive power, a seventh lens group G7 having a negative refractive power, and an eighth lens group G8 having a positive refractive power, which are arranged in order from the object side along the optical axis. When zooming from the wide-angle state (W) to the telephoto state (T), the first to seventh lens groups G1 to G7 move toward the object side along the optical axis, the eighth lens group G8 first moves toward the object side along the optical axis and then moves toward the image side, and the intervals between adjacent lens groups change. The aperture stop S is disposed between the third lens group G3 and the fourth lens group G4. When zooming, the aperture stop S moves along the optical axis together with the fourth lens group G4.

[0152] The first lens group G1 includes a cemented positive lens composed of a negative meniscus lens L11 with a convex surface facing the object side and a positive meniscus lens L12 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis, and a positive meniscus lens L13 with a convex surface facing the object side.

[0153] The second lens group G2 includes a biconcave negative lens L21, which is arranged in order from the object side along the optical axis, and a cemented positive lens composed of a negative meniscus lens L22 with a convex surface facing the object side and a positive meniscus lens L23 with a convex surface facing the object side. The negative lens L21 has an aspherical lens surface on the object side.

[0154] The third lens group G3 is composed of a biconcave negative lens L31.

[0155] The fourth lens group G4 includes a positive meniscus lens L41 with a convex surface facing the object side and a positive meniscus lens L42 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The positive meniscus lens L41 has an aspherical lens surface on the object side.

[0156] The fifth lens group G5 consists of a positive lens formed by the bonding of a negative meniscus lens L51 with a convex surface facing the object and a biconvex positive lens L52, arranged in order from the object side along the optical axis; a negative lens formed by the bonding of a positive meniscus lens L53 with a concave surface facing the object and a negative meniscus lens L54 with a concave surface facing the object; and a positive meniscus lens L55 with a concave surface facing the object. The lens surface of the positive meniscus lens L55 facing the object is aspherical.

[0157] The sixth lens group G6 consists of a biconvex positive lens L61 and a biconcave negative lens L62, which are arranged in order from the object side along the optical axis.

[0158] The seventh lens group G7 consists of a biconcave negative lens L71. The object-facing lens surface of the negative lens L71 is aspherical.

[0159] The eighth lens group G8 consists of a positive meniscus lens L81 with its convex surface facing the object. The image plane I is positioned on the image side of the eighth lens group G8.

[0160] In this embodiment, the first lens group G1 constitutes the front lens group GA, which has a positive refractive power. The second lens group G2 and the third lens group G3 together constitute the first intermediate lens group GM1, which has a negative refractive power as a whole. The fourth lens group G4 and the fifth lens group G5 together constitute the second intermediate lens group GM2, which has a positive refractive power as a whole. The sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 together constitute the subsequent lens group GR, which has a negative refractive power as a whole. When focusing from an object at infinity to an object at a close distance, the sixth lens group G6 and the seventh lens group G7, which constitute the subsequent lens group GR, move toward the image side along the optical axis along different trajectories (amount of movement). That is, the sixth lens group G6 corresponds to the first focusing lens group GF1, which is positioned closest to the object in the subsequent lens group GR. The seventh lens group G7 corresponds to the second focusing lens group GF2, which is another focusing lens group positioned closer to the image than the first focusing lens group GF1.

[0161] Table 5 below lists the specifications of the variable magnification optical system according to the fifth embodiment.

[0162] (Table 5) [Overall Specifications] Multiplication ratio = 7.85 fM1w = -17.295 fM2w = 29.310 MTF1=0.371 MTF2=0.950 βF1w=1.002 βF2w=1.550 βF1t=1.016 βF2t=3.590 fN = -36.530 fL = 180.299 fRw = -44.658 WMT f 24.700 104.916 193.992 FNO 3.98 5.60 6.48 2ω 85.20 22.32 12.46 Ymax 21.60 21.60 21.60 TL 129.45 174.02 204.45 BF 12.454 43.256 39.757 [Lens Specifications] Face number RD nd νd Object plane ∞ 1 140.6369 2.000 1.73800 32.33 2 54.2993 7.774 1.59319 67.90 3 306.9344 0.200 4 70.1192 5.137 1.77250 49.62 5 433.0896 (D5) 6* -348.9741 1.500 1.88202 37.22 7 18.5669 4.368 8 132.2861 1.000 1.49782 82.57 9 19.1562 4.619 1.85000 27.03 10 92.2216 (D10) 11 -59.9587 1.000 1.77250 49.62 12 207.6789 (D12) 13 ∞ 2.000 (Aperture S) 14* 29.0382 2.246 1.67798 54.89 15 56.3251 0.200 16 35.5481 2.153 1.80809 22.74 17 64.9456 (D17) 18 22.8201 1.147 1.90265 35.77 19 14.0716 6.794 1.49782 82.57 20 -62.9717 0.250 21 -578.5647 3.866 1.51680 64.13 22 -26.3104 1.000 2.00069 25.46 23 -262.9123 0.400 24* -252.2011 4.807 1.55332 71.68 25 -20.2354 (D25) 26 406.6131 4.916 1.80809 22.74 27 -31.2178 0.200 28 -44.1001 1.000 1.81600 46.59 29 76.8052 (D29) 30* -65.9674 1.500 1.77387 47.25 31 49.9596 (D31) 32 48.7044 2.979 1.68893 31.16 33 78.1205 BF Image plane ∞ [Aspherical data] The 6th surface κ = 1.0000, A4 = 6.01924E-06, A6 = -9.78216E-09, A8 = 1.91188E-11, A10 = -2.54581E-14 The 14th surface κ = 1.0000, A4 = -8.67328E-06, A6 = -1.41146E-08, A8 = 1.05557E-10, A10 = -7.15518E-13 The 24th surface κ = 1.0000, A4 = -3.58225E-05, A6 = 5.16946E-08, A8 = -2.69722E-10, A10 = 2.25425E-12 The 30th surface κ = 1.0000, A4 = -5.04731E-06, A6 = -3.08030E-08, A8 = 1.84868E-10, A10 = -5.03672E-13 [Variable interval data] Infinity focus state, close - up focus state W M T W M T D5 2.591 35.849 51.107 2.591 35.849 51.107 D10 2.474 1.925 1.779 2.474 1.925 1.779 D12 19.518 4.834 2.144 19.518 4.834 2.144 D17 13.288 4.561 2.000 13.288 4.561 2.000 D25 7.742 3.790 2.000 7.926 4.060 2.371 D29 4.510 6.280 4.193 5.056 6.817 4.772 D31 3.824 10.476 38.417 3.094 9.669 37.467 [Lens group data] Group, starting surface, focal length G1 1 101.843 G2 6 -28.919 G3 11 -60.130 G4 14 45.188 G5 18 37.275 G6 26 -979.922 G7 30 -36.530 G8 32 180.299

[0163] Figure 14(A) is an aberration diagram of the variable magnification optical system according to the fifth embodiment when focused at infinity at the wide-angle end. Figure 14(B) is an aberration diagram of the variable magnification optical system according to the fifth embodiment when focused at infinity at the telephoto end. Figure 15(A) is an aberration diagram of the variable magnification optical system according to the fifth embodiment when focused at close distance at the wide-angle end. Figure 15(B) is an aberration diagram of the variable magnification optical system according to the fifth embodiment when focused at close distance at the telephoto end. From each aberration diagram, it can be seen that the variable magnification optical system according to the fifth embodiment has excellent imaging performance, with aberrations well corrected from the wide-angle end to the telephoto end, not only when focused at infinity but also when focused at close distance.

[0164] (Sixth embodiment) The sixth embodiment will be described using Figures 16 to 18 and Table 6. Figure 16 is a diagram showing the lens configuration of the variable magnification optical system according to the sixth embodiment. The variable magnification optical system ZL(6) according to the sixth embodiment consists of 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, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having positive refractive power, and an eighth lens group G8 having negative refractive power, all arranged in order from the object side along the optical axis. When magnification is changed from the wide-angle end state (W) to the telephoto end state (T), the first to eighth lens groups G1 to G8 move towards the object side along the optical axis, and the spacing between adjacent lens groups changes. The aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3. During magnification, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0165] The first lens group G1 consists of a bonded positive lens formed by a negative meniscus lens L11 with a convex surface facing the object and a biconvex positive lens L12, and a positive meniscus lens L13 with a convex surface facing the object, arranged in order from the object side along the optical axis.

[0166] The second lens group G2 consists of a negative meniscus lens L21 with its convex surface facing the object, arranged in order from the object side along the optical axis; a bonded positive lens formed by a biconcave negative lens L22 and a biconvex positive lens L23; and a biconcave negative lens L24. The negative meniscus lens L21 has an aspherical lens surface on the object side.

[0167] The third lens group G3 consists of a positive meniscus lens L31 with its convex surface facing the object, a biconvex positive lens L32, and a negative meniscus lens L33 with its concave surface facing the object, all arranged in order from the object side along the optical axis. The positive meniscus lens L31 has an aspherical lens surface on the object side.

[0168] The fourth lens group G4 consists of a biconvex positive lens L41 arranged sequentially from the object side along the optical axis, and a bonded negative lens formed by a negative meniscus lens L42 with its convex surface facing the object side and a biconvex positive lens L43.

[0169] The fifth lens group G5 consists of a negative meniscus lens L51 with its concave surface facing the object.

[0170] The sixth lens group G6 consists of a biconvex positive lens L61.

[0171] The seventh lens group G7 consists of a positive meniscus lens L71 with its concave surface facing the object. The positive meniscus lens L71 has an aspherical lens surface on the image side.

[0172] The eighth lens group G8 consists of a biconcave negative lens L81 and a positive meniscus lens L82 with its convex side facing the object, arranged in order from the object side along the optical axis. The image plane I is positioned on the image side of the eighth lens group G8.

[0173] In this embodiment, the first lens group G1 constitutes the front lens group GA, which has positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1, which has negative refractive power. The third lens group G3 and the fourth lens group G4 together constitute the second intermediate lens group GM2, which has positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 together constitute the subsequent lens group GR, which has negative refractive power as a whole. When focusing from an object at infinity to an object at a close distance, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7, which constitute the subsequent lens group GR, move toward the object along the optical axis with different trajectories (amount of movement). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1, which is positioned closest to the object in the subsequent lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group located closer to the image than the first focusing lens group GF1. The seventh lens group G7 corresponds to the third focusing lens group GF3, which is another focusing lens group located closer to the image than the first focusing lens group GF1.

[0174] Table 6 below lists the specifications of the variable magnification optical system according to the sixth embodiment.

[0175] (Table 6) [Overall Specifications] Multiplication ratio = 4.70 fM1w = -19.907 fM2w = 32.581 MTF1=2.249 MTF2=2.096 βF1w=0.765 βF2w=0.949 βF1t=0.684 βF2t=0.943 fN = -37.608 fL = 176.733 fRw = -190.173 WMT f 24.700 70.009 115.999 FNO 4.06 4.02 4.12 2ω 86.44 32.64 19.92 Ymax 21.60 21.60 21.60 TL 139.45 169.68 199.08 BF 12.344 33.226 39.472 [Lens Specifications] Face number RD nd νd Object plane ∞ 1 462.2978 2.000 1.84666 23.80 2 117.9843 7.772 1.59319 67.90 3 -332.8090 0.200 4 68.5981 5.329 1.77250 49.62 5 140.6044 (D5) 6* 102.1762 1.500 1.74389 49.53 7 20.0193 7.301 8 -53.3166 1.000 1.59319 67.90 9 23.3630 6.829 1.68893 31.16 10 -34.9416 0.488 11 -29.8911 1.000 1.81600 46.59 12 771.9204 (D12) 13 ∞ 2.000 (Aperture S) 14* 64.5221 2.313 1.69343 53.30 15 218.6309 0.200 16 42.2294 5.148 1.59319 67.90 17 -50.9166 0.846 18 -38.4211 1.000 1.83481 42.73 19 -121.6787 (D19) 20 50.5091 4.565 1.59319 67.90 21 -73.4692 0.200 22 144.3902 1.000 1.81600 46.59 23 20.8080 7.069 1.49782 82.57 24 -58.5658 (D24) 25 -36.5746 1.000 1.90200 25.26 26 -88.6629 (D26) 27 78.2651 5.215 1.80400 46.60 28 -61.1685 (D28) 29 -115.4337 1.682 1.77387 47.25 30* -84.6141 (D30) 31 -93.1742 1.000 1.83481 42.73 32 47.5819 1.399 33 51.8920 2.458 1.94594 17.98 34 73.5164 BF Image plane ∞ [Aspherical surface] Page 6 κ=1.0000,A4=1.46132E-06,A6=-1.42920E-09,A8=2.79764E-12,A10=5.33710E-15 Page 14 κ=1.0000,A4=-3.76343E-06,A6=1.16052E-09,A8=-1.11309E-11,A10=1.96066E-14 Page 30 κ=1.0000,A4=9.30832E-06,A6=3.85397E-09,A8=-9.94633E-12,A10=2.27044E-14 [Can change the interval データ] Infinity focus state Close focus state WMTWMT D5 2.000 24.468 49.503 2.000 24.468 49.503 D12 20.478 3.818 2.074 20.478 3.818 2.074 D19 8.916 3.265 2.000 8.916 3.265 2.000 D24 6.612 13.356 22.504 5.023 11.937 20.255 D26 3.664 3.898 2.010 3.909 4.002 2.162 D28 3.789 9.856 8.781 4.421 10.371 9.746 D30 11.138 7.275 2.224 11.850 8.075 3.355 [Lens group data] Group starting plane focal length G1 1 134.376 G2 6 -19.907 G3 14 53.036 G4 20 55.179 G5 25 -69.654 G6 27 43.428 G7 29 399.999 G8 31 -47.335

[0176] Figure 17(A) is a diagram of aberrations when the variable magnification optical system according to the sixth embodiment is focused at infinity at the wide-angle end. Figure 17(B) is a diagram of aberrations when the variable magnification optical system according to the sixth embodiment is focused at infinity at the telephoto end. Figure 18(A) is a diagram of aberrations when the variable magnification optical system according to the sixth embodiment is focused at close range at the wide-angle end. Figure 18(B) is a diagram of aberrations when the variable magnification optical system according to the sixth embodiment is focused at close range at the telephoto end. From each of the aberration diagrams, it can be seen that the variable magnification optical system according to the sixth embodiment has excellent imaging performance, with aberrations well corrected from the wide-angle end to the telephoto end, not only when focused at infinity but also when focused at close range.

[0177] (Seventh Example) The seventh embodiment will be explained using Figures 19 to 21 and Table 7. Figure 19 is a diagram showing the lens configuration of the variable magnification optical system according to the seventh embodiment. The variable magnification optical system ZL(7) according to the seventh embodiment consists of 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 negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having positive refractive power, and an eighth lens group G8 having negative refractive power, all arranged in order from the object side along the optical axis. When magnification is changed from the wide-angle end state (W) to the telephoto end state (T), the first to eighth lens groups G1 to G8 move towards the object side along the optical axis, and the spacing between adjacent lens groups changes. The aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3. During magnification, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0178] The first lens group G1 consists of a bonded positive lens formed by a negative meniscus lens L11 with a convex surface facing the object and a biconvex positive lens L12, and a positive meniscus lens L13 with a convex surface facing the object, arranged in order from the object side along the optical axis.

[0179] The second lens group G2 consists of a negative meniscus lens L21 with its convex surface facing the object, arranged in order from the object side along the optical axis; a bonded positive lens formed by a biconcave negative lens L22 and a biconvex positive lens L23; and a plano-concave negative lens L24 with its plane facing the image side. The negative meniscus lens L21 has an aspherical lens surface on the object side.

[0180] The third lens group G3 consists of two biconvex positive lenses, L31 and L32, arranged in order from the object side along the optical axis. The object-side lens surface of the positive lens L31 is aspherical.

[0181] The fourth lens group G4 consists of a biconcave negative lens L41.

[0182] The fifth lens group G5 consists of a biconvex positive lens L51 arranged in order from the object side along the optical axis, and a bonded positive lens formed by a negative meniscus lens L52 with its convex surface facing the object side and a biconvex positive lens L53.

[0183] The sixth lens group G6 consists of a negative meniscus lens L61 with its concave surface facing the object, and a positive lens L62 with a biconvex shape, arranged in order from the object side along the optical axis.

[0184] The seventh lens group G7 consists of a positive meniscus lens L71 with its concave surface facing the object. The positive meniscus lens L71 has an aspherical lens surface on the image side.

[0185] The eighth lens group G8 consists of a biconcave negative lens L81 and a positive meniscus lens L82 with its convex side facing the object, arranged in order from the object side along the optical axis. The image plane I is positioned on the image side of the eighth lens group G8.

[0186] In this embodiment, the first lens group G1 constitutes the front lens group GA, which has positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1, which has negative refractive power. The third lens group G3, the fourth lens group G4, and the fifth lens group G5 together constitute the second intermediate lens group GM2, which has positive refractive power as a whole. The sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 together constitute the subsequent lens group GR, which has negative refractive power as a whole. When focusing from an object at infinity to an object at a close distance, the sixth lens group G6 and the seventh lens group G7, which constitute the subsequent lens group GR, move toward the object along the optical axis with different trajectories (amount of movement). That is, the sixth lens group G6 corresponds to the first focusing lens group GF1, which is positioned closest to the object in the subsequent lens group GR. The seventh lens group G7 corresponds to the second focusing lens group GF2, which is another focusing lens group positioned closer to the image than the first focusing lens group GF1.

[0187] Table 7 below lists the specifications of the variable magnification optical system according to the seventh embodiment.

[0188] (Table 7) [Overall Specifications] Multiplication ratio = 4.56 fM1w = -20.363 fM2w = 33.345 MTF1=1.381 MTF2=0.984 βF1w=0.763 βF2w=0.948 βF1t=0.650 βF2t=0.940 fN = -30.226 fL = 100.683 fRw = -177.170 WMT f 22.600 70.004 103.000 FNO 4.09 4.09 4.08 2ω 91.56 33.96 22.38 Ymax 21.60 21.60 21.60 TL 139.45 165.05 199.45 BF 11.779 38.577 39.906 [Lens Specifications] Face number RD nd νd Object plane ∞ 1 6659.3699 2.000 1.84666 23.80 2 195.3556 6.352 1.59319 67.90 3 -273.7600 0.200 4 73.6739 4.876 1.77250 49.62 5 149.1863 (D5) 6* 113.0230 1.500 1.74389 49.53 7 19.5406 7.132 8 -63.0618 1.000 1.59319 67.90 9 24.3284 6.267 1.68893 31.16 10 -43.5952 0.573 11 -34.2926 1.000 1.81600 46.59 12 ∞ (D12) 13 ∞ 2.000 (Aperture S) 14* 57.8680 3.090 1.69343 53.30 15 -302.2108 0.200 16 48.4547 4.785 1.59319 67.90 17 -53.3050 (D17) 18 -38.1755 1.000 1.83481 42.730 19 616.7068 (D19) 20 42.1940 4.851 1.59319 67.90 21 -69.0643 0.200 22 98.4698 1.000 1.81600 46.59 23 19.6428 7.597 1.49782 82.57 24 -56.1321 (D24) 25 -29.3608 1.000 1.90200 25.26 26 -58.1915 1.995 27 90.0589 5.380 1.80400 46.60 28 -48.9540 (D28) 29 -85.0115 1.709 1.77387 47.25 30* -65.3126 (D30) 31 -62.1123 1.000 1.83481 42.73 32 42.8077 3.227 33 69.1642 3.143 1.94594 17.98 34 247.0342 BF Image plane ∞ [Aspherical surface] Page 6 κ=1.0000,A4=2.33500E-06,A6=-8.92215E-10,A8=-3.76442E-12,A10=9.61354E-15 Page 14 κ=1.0000,A4=-2.41342E-06,A6=1.12249E-09A8=-3.73343E-13,A10=-1.07003E-14 Page 30 κ=1.0000,A4=9.05002E-06,A6=4.53686E-10,A8=5.24788E-12,A10=-1.61841E-14 [Variable interval data] Infinity focus state Close focus state WMTWMT D5 2.000 17.263 50.507 2.000 17.263 50.507 D12 22.632 2.617 2.000 22.632 2.617 2.000 D17 2.327 2.925 2.897 2.327 2.925 2.897 D19 10.846 2.372 2.000 10.846 2.372 2.000 D24 5.406 14.281 18.351 4.526 13.387 16.970 D28 2.000 8.343 8.382 2.443 8.546 8.779 D30 9.389 5.598 2.334 9.827 6.289 3.318 [Lens group data] Group starting plane focal length G1 1 153.821 G2 6 -20.363 G3 14 27.666 G4 18 -43.034 G5 20 44.173 G6 25 84.579 G7 29 350.941 G8 31 -44.997

[0189] Figure 20(A) is a diagram of aberrations when the variable magnification optical system according to the seventh embodiment is focused at infinity at the wide-angle end. Figure 20(B) is a diagram of aberrations when the variable magnification optical system according to the seventh embodiment is focused at infinity at the telephoto end. Figure 21(A) is a diagram of aberrations when the variable magnification optical system according to the seventh embodiment is focused at close range at the wide-angle end. Figure 21(B) is a diagram of aberrations when the variable magnification optical system according to the seventh embodiment is focused at close range at the telephoto end. From each of the aberration diagrams, it can be seen that the variable magnification optical system according to the seventh embodiment has excellent imaging performance, with aberrations well corrected from the wide-angle end to the telephoto end, not only when focused at infinity but also when focused at close range.

[0190] Next, the table of [Conditional Expression Corresponding Values] is shown below. This table summarizes the values ​​corresponding to each conditional expression (1) to (21) for all examples (Examples 1 to 7). Condition (1) -0.37 <fFs / fFy<0.37 Condition (2) 2.00 <f1 / fw<8.00 Condition (3) -6.00 <fFs / fw<6.00 Conditional expression (4) 4.30 <f1 / (-fM1w)<10.00 Condition (5) 1.50 <f1 / fM21<7.00 Condition (6) 0.10 <BFw / fw<1.00 Conditional expression (7) 0.20<|fFs| / f1<2.00 Conditional expression (8) 1.50<|fFs| / (-fM1w)<5.00 Conditional expression (9) 0.90<|fFs| / fM2w<4.00 Condition (10) 0.20 <f1 / (-fRw)<5.00 Conditional expression (11) 0.10 <MTF1 / MTF2<3.00 Conditional expression (12) 0.10<βF1w / βF2w<3.00 Conditional expression (13) 0.10<βF1t / βF2t<3.00 Condition (14) 0.50 < βF1w < 2.60 Conditional expression (15) 0.20<βF2w<1.80 Conditional expression (16) {βF1w+(1 / βF1w)}-2 ≤0.25 Conditional expression (17) {βF2w+(1 / βF2w)} -2 ≤0.25 Conditional expression (18) 0.10<|fFs| / |fRF|<4.00 Conditional expression (19) 2ωw>75.0° Condition (20) ft / fw > 3.50 Conditional expression (21) 0.10<(-fN) / fL<1.00

[0191] [Conditional Expression Corresponding Values] (Examples 1-4) Conditional expression First example Second example Third example Fourth example (1) 0.119 -0.034 0.217 0.037 (2) 3.932 4.500 6.953 4.181 (3) -1.547 -1.279 3.722 -1.457 (4) 5.502 6.518 7.481 5.766 (5) 2.424 3.217 2.639 2.298 (6) 0.555 0.464 0.507 0.504 (7) 0.393 0.284 0.535 0.349 (8) 2.165 1.852 4.005 2.010 (9) 1.281 1.087 2.511 1.208 (10) 2.094 1.822 0.991 2.321 (11) 0.407 0.284 1.442 0.432 (12) 0.679 0.626 0.807 0.644 (13) 0.359 0.263 0.695 0.282 (14) 1.071 1.045 0.770 1.005 (15) 1.577 1.670 0.954 1.561 (16) 0.249 0.250 0.234 0.250 (17) 0.205 0.194 0.249 0.206 (18) 0.296 0.402 1.922 0.211 (19) 85.22 85.22 91.54 85.20 (20) 4.737 4.737 4.558 7.854 (21) 0.296 0.402 0.303 0.211 [Conditional Expression Corresponding Values] (Examples 5-7) Conditional expression 5th example 6th example 7th example (1) 0.037 0.109 0.241 (2) 4.123 5.440 6.806 (3) -1.479 1.758 3.742 (4) 5.889 6.750 7.554 (5) 2.254 2.534 5.560 (6) 0.504 0.500 0.521 (7) 0.359 0.323 0.550 (8) 2.112 2.182 4.154 (9) 1.246 1.333 2.537 (10) 2.280 0.707 0.868 (11) 0.391 1.073 1.403 (12) 0.647 0.806 0.805 (13) 0.283 0.725 0.692 (14) 1.002 0.765 0.763 (15) 1.550 0.949 0.948 (16) 0.250 0.233 0.233 (17) 0.208 0.249 0.249 (18) 0.203 0.917 1.880 (19) 85.20 86.44 91.56 (20) 7.854 4.696 4.558 (21) 0.203 0.213 0.300

[0192] According to the embodiments described above, by making the focusing lens group smaller and lighter, quiet and fast focusing can be achieved without increasing the size of the lens barrel. Furthermore, a variable magnification optical system can be realized that exhibits minimal aberration fluctuations when changing magnification from the wide-angle end to the telephoto end, and when focusing from an infinity-far object to a close-range object.

[0193] The above embodiments illustrate specific examples of the present invention, and the present invention is not limited to these.

[0194] The following elements can be appropriately incorporated as long as they do not impair the optical performance of the variable magnification optical system of this embodiment.

[0195] Although the 7-group and 8-group configurations of the variable magnification optical system of this embodiment have been shown, this application is not limited to these, and variable magnification optical systems with other group configurations (for example, 9 groups, etc.) can also be constructed. Specifically, the variable magnification optical system of this embodiment may be configured by adding lenses or lens groups to the object side or the image plane side. A lens group refers to a portion having at least one lens separated by an air gap that changes during magnification.

[0196] A focusing lens group can be formed by moving a single or multiple lens groups, or a partial lens group, along the optical axis to focus from an object at infinity to an object at close range. The focusing lens group can also be applied to autofocus and is suitable for motor drive (using an ultrasonic motor, etc.) for autofocus.

[0197] A lens group or partial lens group may be moved so that it has a component perpendicular to the optical axis, or rotated (oscillated) in an in-plane direction including the optical axis, to correct image blur caused by camera shake.

[0198] The lens surface may be formed as a spherical, flat, or aspherical surface. A spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment, preventing degradation of optical performance due to processing and assembly errors. It is also preferable because it minimizes degradation of image rendering performance even if the image plane is misaligned.

[0199] If the lens surface is aspherical, it can be an aspherical surface created by grinding, a glass molded aspherical surface formed from glass using a mold, or a composite aspherical surface formed by creating an aspherical shape from resin on the surface of glass. Furthermore, the lens surface may also be a diffractive surface, and the lens may be a refractive index distributed lens (GRIN lens) or a plastic lens.

[0200] The aperture diaphragm is preferably positioned between the second and third lens groups, or between the third and fourth lens groups, but its function may be substituted by the lens frame without providing a separate aperture diaphragm component.

[0201] Each lens surface may be coated with an anti-reflective coating that has high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high contrast optical performance. [Explanation of symbols]

[0202] G1 First lens group G2 Second lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group, G8 8th lens group I Image plane S Aperture diaphragm

Claims

[Claim 1] It has a front lens group with positive refractive power, a first intermediate lens group with negative refractive power, a second intermediate lens group with positive refractive power, and a subsequent lens group, all arranged in order from the object side along the optical axis. During magnification, the spacing between adjacent lens groups changes. The successor lens group includes a first focusing lens group positioned closest to the object and moving along the optical axis when focusing, and at least one other focusing lens group positioned closer to the image than the first focusing lens group and moving along the optical axis on a different trajectory than the first focusing lens group when focusing. A variable magnification optical system that satisfies the following conditions. -0.37<fFs / fFy<0.37 2.00<f1 / fw<8.00 However, fFs: The focal length of the focusing lens group with the strongest refractive power among the focusing lens groups included in the aforementioned successor lens group. fFy: The focal length of the focusing lens group with the weakest refractive power among the focusing lens groups included in the aforementioned successor lens group. f1: Focal length of the front lens group fw: Focal length of the variable magnification optical system at the wide-angle end.

Images