Variable power optical system and optical device

Abstract

To provide a variable power optical system suppressing an aberration variation in focusing.SOLUTION: A variable power optical system ZL includes a front-side lens group GA that is lined up from an object side along a light axis and has 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 subsequent lens group GR, and also includes a first focusing lens group GF1 disposed in the furthest object side of the subsequent lens group GR while the interval between respective adjacent lens groups is changed in scaling, and at least one another focusing lens group, the focusing lens group closest to the first focusing lens group GF1 is composed of one lens component, and a following conditional expression is satisfied, namely, -6.00<fFs / fw<6.00, where fFs is a focal distance of a focusing lens group having the strongest refractive power from among focusing lens groups, and fw is a focal distance of the variable power optical system ZL in a wide-angle end state.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Variable magnification optical systems suitable for photo 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] JP 2019-12243 A Summary of the Invention

[0004] The variable magnification optical system of the present invention has, arranged in order from the object side along the optical axis, 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 rear lens group, wherein the distance between adjacent lens groups changes during magnification, and the rear lens group includes a first focusing lens group that is arranged closest to the object side of the rear lens group and moves along the optical axis during focusing, and at least one other focusing lens group that is arranged closer to the image side than the first focusing lens group and moves along the optical axis along a different locus from the first focusing lens group during focusing, and the focusing lens group closest to the first focusing lens group among the other focusing lens groups is composed of one lens component and satisfies the following conditional expression. -6.00 <fFs / fw<6.00 where fFs is the focal length of the focusing lens group having the strongest refractive power among the focusing lens groups included in the subsequent lens group. fw: focal length of the variable magnification optical system in the wide-angle end state

[0005] An optical device according to the present invention includes the variable magnification optical system described above. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a diagram showing a lens configuration of a variable magnification optical system according to a first example. [Diagram 2] 2A and 2B are diagrams showing various aberrations of the variable magnification optical system according to Example 1 when focused on infinity in the wide-angle end state and the telephoto end state, respectively. [Diagram 3] 3A and 3B are diagrams showing various aberrations of the variable magnification optical system according to Example 1 when focused on a close object in the wide-angle end state and the telephoto end state, respectively. [Figure 4] FIG. 13 is a diagram showing a lens configuration of a variable magnification optical system according to Example 2. [Diagram 5] 5A and 5B are diagrams showing various aberrations of the variable magnification optical system according to the second example when focused on infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 6] 6A and 6B are diagrams showing various aberrations of the variable magnification optical system according to the second example when focusing on a close object in the wide-angle end state and the telephoto end state, respectively. [Figure 7] FIG. 13 is a diagram showing the lens configuration of a variable magnification optical system according to Example 3. [Figure 8] 8A and 8B are diagrams showing various aberrations of the variable magnification optical system according to Example 3 when focused on infinity in the wide-angle end state and in the telephoto end state, respectively. [Figure 9] 9A and 9B are diagrams showing various aberrations of the variable magnification optical system according to Example 3 when focused on a close object in the wide-angle end state and the telephoto end state, respectively. [Figure 10] FIG. 13 is a diagram showing the lens configuration of a variable magnification optical system according to Example 4. [Figure 11] 11A and 11B are diagrams showing various aberrations of the variable magnification optical system according to Example 4 when focused on infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 12] 12A and 12B are diagrams showing various aberrations of the variable magnification optical system according to Example 4 when focused on a close object in the wide-angle end state and the telephoto end state, respectively. [Figure 13]FIG. 13 is a diagram showing the lens configuration of a variable magnification optical system according to Example 5. [Figure 14] 14A and 14B are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focused on infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 15] 15A and 15B are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focusing on a close object in the wide-angle end state and the telephoto end state, respectively. [Figure 16] FIG. 13 is a diagram showing the lens configuration of a variable magnification optical system according to Example 6. [Figure 17] 17A and 17B are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focused on infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 18] 18A and 18B are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focused on a close object in the wide-angle end state and the telephoto end state, respectively. [Figure 19] FIG. 13 is a diagram showing the lens configuration of a variable magnification optical system according to Example 7. [Figure 20] 20A and 20B are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focused on an object at infinity in the wide-angle end state and in the telephoto end state, respectively. [Figure 21] 21A and 21B are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focusing on a close object in the wide-angle end state and the telephoto end state, respectively. [Figure 22] FIG. 1 is a diagram showing the configuration of a camera equipped with a variable magnification optical system according to an embodiment of the present invention. [Diagram 23] 5 is a flowchart showing a method of manufacturing a variable magnification optical system according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] A preferred embodiment of the present invention will be described below. First, a camera (optical device) equipped with a variable magnification optical system according to this embodiment will be described with reference to FIG. 22. As shown in FIG. 22, this camera 1 is composed of a body 2 and a photographing lens 3 attached to the body 2. The body 2 is equipped with an image sensor 4, a body control unit (not shown) that controls the operation of the digital camera, and a liquid crystal screen 5. The photographing lens 3 is equipped with a variable magnification optical system ZL consisting of a plurality of lens groups, and a lens position control mechanism (not shown) that controls the position of each lens group. The lens position control mechanism is composed of a sensor that detects the position of the lens groups, a motor that moves the lens groups back and forth along the optical axis, a control circuit that drives the motor, and the like.

[0008] Light from a subject is collected by the variable magnification optical system ZL of the photographing 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 a memory (not shown). The digital image data recorded in the memory can be displayed on the liquid crystal screen 5 in response to a user's operation. This camera may be a mirrorless camera or a single-lens reflex camera having a quick return mirror. The variable magnification optical system ZL shown in FIG. 22 is a schematic diagram of a variable magnification optical system provided in the photographing lens 3, and the lens configuration of the variable magnification optical system ZL is not limited to this configuration.

[0009] Next, a variable magnification optical system according to this embodiment will be described. As shown in FIG. 1, a variable magnification optical system ZL(1) as an example of a variable magnification optical system (zoom lens) ZL according to this embodiment is configured to include 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 rear lens group GR, which are arranged in order from the object side along the optical axis. When changing magnification, the interval between adjacent lens groups changes. The rear lens group GR includes a first focusing lens group GF1, which is disposed closest to the object side of the rear lens group GR and moves along the optical axis during focusing, and at least one other focusing lens group, which is disposed closer to the image side than the first focusing lens group GF1 and moves along the optical axis on a different trajectory from the first focusing lens group GF1 during focusing. In addition, the focusing lens group closest to the first focusing lens group GF1 among the other focusing lens groups is configured of one lens component.

[0010] With the above-mentioned configuration, the variable magnification optical system ZL according to this embodiment satisfies the following conditional expression (1). -6.00 <fFs / fw<6.00 ···(1) where fFs is 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. fw: focal length of the variable magnification optical system ZL at the wide-angle end

[0011] According to this embodiment, it is possible to obtain a variable magnification optical system with little aberration fluctuation during focusing, and an optical device equipped with this variable magnification optical system. In addition, since the rear lens group GR has a plurality of focusing lens groups, it is possible to suppress the fluctuation of various aberrations, including spherical aberration, during focusing without increasing the size of the focusing lens group. In addition, by changing the spacing between adjacent lens groups during magnification, it is possible to perform good aberration correction during magnification.

[0012] The variable magnification optical system ZL according to this embodiment may be the variable magnification optical system ZL(2) shown in Fig. 4, the variable magnification optical system ZL(3) shown in Fig. 7, or the variable magnification optical system ZL(4) shown in Fig. 10. Moreover, the variable magnification optical system ZL according to this embodiment may be the variable magnification optical system ZL(5) shown in Fig. 13, the variable magnification optical system ZL(6) shown in Fig. 16, or the variable magnification optical system ZL(7) shown in Fig. 19.

[0013] Conditional formula (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 variable magnification optical system ZL in the wide-angle end state. By satisfying conditional formula (1), it is possible to suppress fluctuations in various aberrations, including spherical aberration, during focusing.

[0014] When the corresponding value of conditional expression (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 small, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. The effect of this embodiment can be made more certain by setting the upper limit of conditional expression (1) to 5.50, 5.00, 4.80, 4.50, 4.00, or even 3.80.

[0015] If the corresponding value of conditional expression (1) falls below the lower limit, the refractive power of the focusing lens group with the strongest refractive power becomes strong, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. The effect of this embodiment can be made more certain by setting the lower limit of conditional expression (1) to -5.50, -5.00, -4.50, -4.00, -3.50, -3.00, -2.50, -2.00, or even -1.80.

[0016] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (2). 2.00 <f1 / fw<8.00 ···(2) where f1 is the focal length of the front lens group GA

[0017] Conditional formula (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 in the wide-angle end state. By satisfying conditional formula (2), it is possible to suppress fluctuations in various aberrations, including spherical aberration, during magnification change without increasing the size of the lens barrel.

[0018] When the corresponding value of conditional expression (2) exceeds the upper limit, the refractive power of the front lens group GA becomes weak, so that the amount of movement of the front lens group GA during magnification change increases, and the lens barrel becomes large. By setting the upper limit of conditional expression (2) to 7.80, 7.50, 7.40, 7.00, 6.50, 6.30, or even 6.00, the effect of this embodiment can be further ensured.

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

[0020] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (3). 0.10 <BFw / fw<1.00 ···(3) Where, BFw: back focus of the variable magnification optical system ZL in the wide-angle end state

[0021] Conditional expression (3) defines an appropriate relationship between the back focus of the variable magnification optical system ZL in the wide-angle end state and the focal length of the variable magnification optical system ZL in the wide-angle end state. By satisfying conditional expression (3), various aberrations including coma in the wide-angle end state can be effectively corrected.

[0022] When the corresponding value of conditional expression (3) exceeds the upper limit, the back focus of the variable magnification optical system ZL in the wide-angle end state becomes large relative to the focal length of the variable magnification optical system ZL in the wide-angle end state, making it difficult to correct various aberrations including coma in the wide-angle end state. By setting the upper limit of conditional expression (3) to 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, or even 0.60, the effect of this embodiment can be made more certain.

[0023] If the corresponding value of conditional expression (3) falls below the lower limit, the back focus of the variable magnification optical system ZL in the wide-angle end state becomes small relative to the focal length of the variable magnification optical system ZL in the wide-angle end state, making it difficult to correct various aberrations, including coma aberration, in the wide-angle end state. In addition, it becomes difficult to arrange the mechanical components of the lens barrel. By setting the lower limit of conditional expression (3) to 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, or even 0.43, the effect of this embodiment can be made more certain.

[0024] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (4). 0.20<|fFs| / f1<2.00 (4) where f1 is the focal length of the front lens group GA

[0025] Conditional formula (4) specifies 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 rear lens group GR and the focal length of the front lens group GA. By satisfying conditional formula (4), it is possible to suppress fluctuations in various aberrations, including spherical aberration, during focusing without increasing the size of the lens barrel. In addition, it is possible to suppress fluctuations in various aberrations, including spherical aberration, during magnification change without increasing the size of the lens barrel.

[0026] If the corresponding value of conditional expression (4) exceeds the upper limit, the refractive power of the focusing lens group becomes weak, so the amount of movement of the focusing lens group during focusing becomes large, and the lens barrel becomes large. Also, the refractive power of the front lens group GA becomes strong, so it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, during zooming. By setting the upper limit of conditional expression (4) to 1.80, 1.50, 1.30, 1.00, 0.85, 0.70, 0.65, 0.60, or even 0.58, the effect of this embodiment can be made more certain.

[0027] If the value of conditional expression (4) falls below the lower limit, the refractive power of the focusing lens group becomes strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, during focusing. Also, the refractive power of the front lens group GA becomes weak, so the amount of movement of the front lens group GA during zooming becomes large, and the lens barrel becomes large. By setting the lower limit of conditional expression (4) to 0.22, 0.24, 0.25, or even 0.26, the effect of this embodiment can be more reliably achieved.

[0028] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (5). 1.50<|fFs| / (-fM1w)<5.00 (5) where fM1w is the focal length of the first intermediate lens group GM1 in the wide-angle end state.

[0029] Conditional formula (5) specifies 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 rear lens group GR and the focal length of the first intermediate lens group GM1 in the wide-angle end state. By satisfying conditional formula (5), it is possible to suppress fluctuations in various aberrations, including spherical aberration, during focusing. In addition, it is possible to effectively correct various aberrations, including coma aberration, in the wide-angle end state.

[0030] When the corresponding value of conditional expression (5) exceeds the upper limit, the refractive power of the first intermediate lens group GM1 in the wide-angle end state becomes strong, making it difficult to correct various aberrations including coma in the wide-angle end state. The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (5) to 4.85, 4.70, 4.50, 4.35, 4.25, 3.85, 3.50, 3.00, or even 2.50.

[0031] If the corresponding value of conditional expression (5) falls below the lower limit, the refractive power of the focusing lens group becomes strong, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional expression (5) to 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, or even 1.83, the effect of this embodiment can be made more certain.

[0032] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (6). 0.90<|fFs| / fM2w<4.00 (6) where fM2w is the focal length of the second intermediate lens group GM2 in the wide-angle end state.

[0033] Conditional formula (6) specifies 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 rear lens group GR and the focal length of the second intermediate lens group GM2 in the wide-angle end state. By satisfying conditional formula (6), it is possible to suppress fluctuations in various aberrations, including spherical aberration, during focusing. In addition, it is possible to effectively correct various aberrations, including coma aberration, in the wide-angle end state.

[0034] When the corresponding value of conditional expression (6) exceeds the upper limit, the refractive power of the second intermediate lens group GM2 in the wide-angle end state becomes strong, making it difficult to correct various aberrations including coma in the wide-angle end state. The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (6) to 3.80, 3.50, 3.30, 3.00, 2.80, 2.60, 2.00, 1.80, or further to 1.50.

[0035] If the corresponding value of conditional expression (6) falls below the lower limit, the refractive power of the focusing lens group becomes strong, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional expression (6) to 0.95, 0.98, 1.00, 1.03, or even 1.05, the effect of this embodiment can be made more certain.

[0036] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (7). 0.20 <f1 / (-fRw)<5.00 ···(7) where f1 is the focal length of the front lens group GA fRw: focal length of the rear lens group GR in the wide-angle end state

[0037] Condition (7) defines an appropriate relationship between the focal length of the front lens group GA and the focal length of the rear lens group GR in the wide-angle end state. By satisfying condition (7), it is possible to effectively correct various aberrations, including coma in the wide-angle end state, without increasing the size of the lens barrel.

[0038] If the corresponding value of conditional expression (7) exceeds the upper limit, the refractive power of the rear lens group GR in the wide-angle end state becomes strong, making it difficult to correct various aberrations, including coma aberration in the wide-angle end state. Also, the refractive power of the front lens group GA becomes weak, so the amount of movement of the front lens group GA during magnification change becomes large, and the lens barrel becomes large. The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (7) to 4.50, 4.00, 3.80, 3.50, 3.30, 3.00, 2.80, or even 2.50.

[0039] When the corresponding value of conditional expression (7) falls below the lower limit, the refractive power of the rear lens group GR in the wide-angle end state becomes weak, making it difficult to correct various aberrations including coma in the wide-angle end state. By setting the lower limit of conditional expression (7) to 0.40, 0.50, 0.60, 0.65, 0.68, or even 0.70, the effect of this embodiment can be made more certain.

[0040] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (8). 0.10 <MTF1 / MTF2<3.00 ···(8) However, MTF1: Absolute value of the movement amount of the first focusing lens group GF1 when focusing from an object at infinity to an object at a close distance in the telephoto end state MTF2: Absolute value of the amount of movement of the focusing lens group that is closest to the first focusing lens group GF1 among the other focusing lens groups when focusing from an object at infinity to a close object in the telephoto end state

[0041] Conditional expression (8) 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 close object in the telephoto end state and the amount of movement of the focusing lens group closest to the first focusing lens group GF1. By satisfying conditional expression (8), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the telephoto end state.

[0042] If the corresponding value of conditional expression (8) exceeds the upper limit, the movement amount of the first focusing lens group GF1 becomes too large when focusing from an object at infinity to an object at a close distance in the telephoto end state, making it difficult to suppress fluctuations in various aberrations including spherical aberration. The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (8) to 2.80, 2.50, 2.30, 2.00, 1.80, 1.65, or even 1.50.

[0043] If the value of conditional expression (8) 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 close object in the telephoto end state, making it difficult to suppress fluctuations in various aberrations including spherical aberration. The effect of this embodiment can be further ensured by setting the lower limit of conditional expression (8) to 0.13, 0.15, 0.18, 0.20, 0.23, or even 0.25.

[0044] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (9). 0.10<βF1w / βF2w<3.00 (9) where βF1w is the composite lateral magnification of the focusing lens group included in the subsequent lens group GR, which is located closer to the object side than the focusing lens group closest to the image side, when focusing on an object at infinity in the wide-angle end state. βF2w: The lateral magnification of the focusing lens group included in the subsequent lens group GR, which is closest to the image side, when focusing on an object at infinity in the wide-angle end state

[0045] Conditional expression (9) specifies an appropriate relationship between the lateral magnification of the focusing lens group closest to the image among the focusing lens groups included in the subsequent lens group GR when focusing on an object at infinity in the wide-angle end state, and the combined lateral magnification of the focusing lens group located closer to the object than the focusing lens group closest to the image when focusing on an object at infinity in the wide-angle end state. By satisfying conditional expression (9), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the wide-angle end state.

[0046] If the value of conditional expression (9) exceeds the upper limit, the combined lateral magnification of the focusing lens group located closer to the object than the focusing lens group closest to the image becomes too large when focusing on an object at infinity in the wide-angle end state. Therefore, it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the wide-angle end state. The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (9) to 2.80, 2.50, 2.30, 2.00, 1.80, 1.50, 1.30, 1.00, or even 0.90.

[0047] If the value of conditional expression (9) falls below the lower limit, the lateral magnification of the focusing lens group closest to the image when focusing on an object at infinity in the wide-angle end state becomes too large. Therefore, it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the wide-angle end state. The effect of this embodiment can be further ensured by setting the lower limit of conditional expression (9) to 0.20, 0.35, 0.50, 0.55, 0.58, or even 0.60.

[0048] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (10). 0.10<βF1t / βF2t<3.00 (10) where βF1t is the composite lateral magnification of the focusing lens group included in the subsequent lens group GR, the focusing lens group located closer to the object side than the focusing lens group closest to the image side, when focusing on an object at infinity in the telephoto end state. βF2t: The lateral magnification of the focusing lens group closest to the image side among the focusing lens groups included in the subsequent lens group GR when focusing on an object at infinity in the telephoto end state

[0049] Conditional expression (10) specifies an appropriate relationship between the lateral magnification of the focusing lens group closest to the image among the focusing lens groups included in the rear lens group GR when focusing on an object at infinity in the telephoto end state, and the combined lateral magnification of the focusing lens group located closer to the object than the focusing lens group closest to the image when focusing on an object at infinity in the telephoto end state. By satisfying conditional expression (10), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the telephoto end state.

[0050] If the corresponding value of conditional expression (10) exceeds the upper limit, the combined lateral magnification of the focusing lens group located closer to the object than the focusing lens group closest to the image becomes too large when focusing on an object at infinity in the telephoto end state. Therefore, it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the telephoto end state. The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (10) to 2.80, 2.50, 2.30, 2.00, 1.80, 1.50, 1.30, 1.00, or even 0.80.

[0051] If the value of conditional expression (10) falls below the lower limit, the lateral magnification of the focusing lens group closest to the image when focusing on an object at infinity in the telephoto end state becomes too large. Therefore, it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the telephoto end state. The effect of this embodiment can be further ensured by setting the lower limit of conditional expression (10) to 0.13, 0.15, 0.18, 0.20, 0.23, or even 0.25.

[0052] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (11). 0.50<βF1w<2.60 (11) where βF1w is the composite lateral magnification of the focusing lens group included in the subsequent lens group GR, which is located closer to the object side than the focusing lens group closest to the image side, when focusing on an object at infinity in the wide-angle end state.

[0053] Conditional expression (11) defines an appropriate range for the composite lateral magnification when focusing on an object at infinity in the wide-angle end state of the focusing lens group that is located closer to the object than the focusing lens group closest to the image, among the focusing lens groups included in the subsequent lens group GR. By satisfying conditional expression (11), it is possible to suppress fluctuations in various aberrations, including spherical aberration and coma, during focusing.

[0054] If the corresponding value of conditional expression (11) exceeds the upper limit, it becomes difficult to suppress fluctuations in various aberrations during focusing. By setting the upper limit of conditional expression (11) to 2.58, 2.55, 2.00, 1.80, 1.50, 1.30, or further to 1.20, the effect of this embodiment can be made more certain.

[0055] If the corresponding value of conditional expression (11) falls below the lower limit, it becomes difficult to suppress fluctuations in various aberrations during focusing. By setting the lower limit of conditional expression (11) to 0.55, 0.60, 0.65, 0.70, or even 0.73, the effect of this embodiment can be made more certain.

[0056] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (12). 0.20<βF2w<1.80 (12) where βF2w is the lateral magnification of the focusing lens group closest to the image side among the focusing lens groups included in the subsequent lens group GR when focusing on an object at infinity in the wide-angle end state.

[0057] Conditional expression (12) specifies an appropriate range for the lateral magnification of the focusing lens group closest to the image among the focusing lens groups included in the rear lens group GR when focusing on an object at infinity in the wide-angle end state. By satisfying conditional expression (12), it is possible to suppress fluctuations in various aberrations, including spherical aberration and coma, during focusing.

[0058] If the corresponding value of conditional expression (12) exceeds the upper limit, it becomes difficult to suppress fluctuations in various aberrations during focusing. By setting the upper limit of conditional expression (12) to 1.78, 1.75, 1.73, 1.70, 1.68, or further to 1.60, the effect of this embodiment can be made more certain.

[0059] If the corresponding value of conditional expression (12) falls below the lower limit, it becomes difficult to suppress fluctuations in various aberrations during focusing. By setting the lower limit of conditional expression (12) to 0.23, 0.25, or even 0.28, the effect of this embodiment can be made more certain.

[0060] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (13). {βF1w+(1 / βF1w)} -2 ≦0.25 (13) where βF1w is the composite lateral magnification of the focusing lens group included in the subsequent lens group GR, which is located closer to the object side than the focusing lens group closest to the image side, when focusing on an object at infinity in the wide-angle end state.

[0061] Conditional expression (13) specifies an appropriate range for the composite lateral 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 among the focusing lens groups included in the subsequent lens group GR. By satisfying conditional expression (13), it is possible to suppress the fluctuation of various aberrations, including spherical aberration and coma aberration, during focusing. If the corresponding value of conditional expression (13) exceeds the upper limit, it becomes difficult to suppress the fluctuation of various aberrations during focusing.

[0062] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (14). {βF2w+(1 / βF2w)} -2 ≦0.25 (14) where βF2w is the lateral magnification of the focusing lens group closest to the image side among the focusing lens groups included in the subsequent lens group GR when focusing on an object at infinity in the wide-angle end state.

[0063] Conditional expression (14) specifies an appropriate range for the lateral magnification of the focusing lens group closest to the image among the focusing lens groups included in the subsequent lens group GR when focusing on an object at infinity in the wide-angle end state. By satisfying conditional expression (14), it is possible to suppress the fluctuation of various aberrations, including spherical aberration and coma, during focusing. If the corresponding value of conditional expression (14) exceeds the upper limit, it becomes difficult to suppress the fluctuation of various aberrations during focusing.

[0064] In the variable magnification optical system ZL according to this embodiment, it is desirable for the rear lens group GR to include at least one lens group that is arranged closer to the image side than the focusing lens group closest to the image side among the focusing lens groups included in the rear lens group GR, thereby making it possible to effectively suppress fluctuations in various aberrations including spherical aberration during focusing.

[0065] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (15). 0.10<|fFs| / |fRF|<4.00 ···(15) where fRF is the focal length of the lens group that is adjacent to the focusing lens group that is closest to the image side, among the at least one lens group.

[0066] Condition (15) specifies 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 rear lens group GR and the focal length of the lens group arranged adjacent to the image side of the focusing lens group closest to the image side. By satisfying condition (15), fluctuations in various aberrations, including spherical aberration, during focusing can be suppressed.

[0067] If the corresponding value of conditional expression (15) exceeds the upper limit, the refractive power of the lens group arranged adjacent to the focusing lens group closest to the image side becomes strong, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. The effect of this embodiment can be made more certain by setting the upper limit of conditional expression (15) to 3.80, 3.50, 3.30, 3.00, 2.80, 2.50, 2.30, 2.00, 1.50, 1.30, or even 1.00.

[0068] If the corresponding value of conditional expression (15) falls below the lower limit, the refractive power of the focusing lens group becomes strong, making it difficult to suppress fluctuations in various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional expression (15) to 0.13, 0.15, or even 0.18, the effect of this embodiment can be made more certain.

[0069] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (16). 2ωw>75.0° (16) However, 2ωw: the total angle of view of the variable magnification optical system ZL in the wide-angle end state

[0070] Conditional expression (16) defines an appropriate range for the total angle of view of the variable magnification optical system ZL in the wide-angle end state. By satisfying conditional expression (16), a variable magnification optical system with a wide angle of view can be obtained, which is preferable. By setting the lower limit of conditional expression (16) to 78.0°, 80.0°, or even 83.0°, the effect of this embodiment can be further ensured.

[0071] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (17). ft / fw>3.50 ···(17) Where ft: focal length of the variable magnification optical system ZL at the telephoto end

[0072] Conditional expression (17) defines an appropriate relationship between the focal length of the variable magnification optical system ZL in the telephoto end state and the focal length of the variable magnification optical system ZL in the wide-angle end state. By satisfying conditional expression (17), a variable magnification optical system with a high variable magnification ratio can be obtained, which is preferable. By setting the lower limit of conditional expression (17) to 3.80, 4.00, 4.20, or further 4.40, the effect of this embodiment can be further ensured.

[0073] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (18). 0.10<(-fN) / fL<1.00 (18) where fN is the focal length of the second lens from the image side of the variable magnification optical system ZL. fL: focal length of the lens located closest to the image in the variable magnification optical system ZL

[0074] Conditional expression (18) specifies the appropriate relationship between the focal length of the second lens from the image side of the variable magnification optical system ZL and the focal length of the lens closest to the image side of the variable magnification optical system ZL. By satisfying conditional expression (18), various aberrations, including coma in the wide-angle end state, can be effectively corrected.

[0075] If the corresponding value of conditional expression (18) exceeds the upper limit, the refractive power of the lens arranged closest to the image side in the variable magnification optical system ZL becomes strong, making it difficult to correct various aberrations including coma in the wide-angle end state. The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (18) to 0.95, 0.90, 0.85, 0.83, 0.80, 0.78, 0.75, 0.73, or even 0.70.

[0076] If the corresponding value of conditional expression (18) falls below the lower limit, the refractive power of the lens arranged second from the image side of the variable magnification optical system ZL becomes strong, making it difficult to correct various aberrations including coma in the wide-angle end state. By setting the lower limit of conditional expression (18) to 0.13, 0.15, or even 0.18, the effect of this embodiment can be made more certain.

[0077] Next, the manufacturing method of the variable magnification optical system ZL described above will be outlined with reference to FIG. 23. First, the front lens group GA having positive refractive power, the first intermediate lens group GM1 having negative refractive power, the second intermediate lens group GM2 having positive refractive power, and the rear lens group GR are arranged in order from the object side along the optical axis (step ST1). Next, the arrangement is made so that the interval between adjacent lens groups changes during magnification (step ST2). Next, the first focusing lens group GF1 that moves along the optical axis during focusing is arranged on the most object side of the rear lens group GR, and at least one other focusing lens group that moves along the optical axis on a different trajectory from the first focusing lens group GF1 during focusing is arranged on the image side of the first focusing lens group GF1 in the rear lens group GR (step ST3). Next, one lens component is arranged in the focusing lens group closest to the first focusing lens group GF1 among the other focusing lens groups (step ST4). Then, the lenses are arranged in the lens barrel so as to satisfy at least the above conditional expression (1) (step ST5). According to this manufacturing method, it is possible to manufacture a variable magnification optical system with little aberration fluctuation during focusing. EXAMPLES

[0078] Hereinafter, the variable magnification optical system ZL according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1, FIG. 4, FIG. 7, FIG. 10, FIG. 13, FIG. 16, and FIG. 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 examples. In the cross-sectional views of the variable magnification optical systems ZL(1) to ZL(7) according to the first to seventh examples, the movement direction along the optical axis of the focusing group when focusing from infinity to a close object is indicated by an arrow together with the word "focusing". In the cross-sectional views of the variable magnification optical systems ZL(1) to ZL(7) according to the first to seventh examples, the movement direction along the optical axis of each lens group when changing magnification from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow.

[0079] 1, 4, 7, 10, 13, 16, and 19, each lens group is represented by a combination of the symbol G and a number, and each lens is represented by a combination of the symbol L and a number. In this case, to prevent the symbols and numbers from becoming too large and becoming complicated in number, the lens groups, etc. are represented by their own combinations of symbols and numbers for each embodiment. Therefore, even if the same combinations of symbols and numbers are used between embodiments, this does not mean that they have the same configuration.

[0080] Tables 1 to 7 are shown below, with Table 1 showing data on the various elements in the first embodiment, Table 2 showing data on the second embodiment, Table 3 showing data on the third embodiment, Table 4 showing data on the fourth embodiment, Table 5 showing data on the fifth embodiment, Table 6 showing data on the sixth embodiment, and Table 7 showing data on the seventh embodiment. In each embodiment, the d-line (wavelength λ=587.6 nm) and g-line (wavelength λ=435.8 nm) are selected as the targets for calculating the aberration characteristics.

[0081] 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 (units are ° (degrees), where ω is half the angle of view), and Ymax is the maximum image height. TL is the distance from the frontmost lens surface to the final lens surface on the optical axis when focused at infinity plus BF, and BF is the distance (back focus) from the final lens surface to image plane I on the optical axis when focused at infinity. These values ​​are shown for both the wide-angle end (W) and the telephoto end (T) magnification settings.

[0082] In the table of [Overall Specifications], fM1w indicates the focal length of the first intermediate lens group in the wide-angle end state. fM2w indicates the focal length of the second intermediate lens group in the wide-angle end state. MTF1 indicates the absolute value of the movement amount of the first focusing lens group when focusing from an infinite object to a close object in the telephoto end state. MTF2 indicates the absolute value of the movement amount of the focusing lens group closest to the first focusing lens group among the other focusing lens groups when focusing from an infinite object to a close object in the telephoto end state. βF1w indicates the combined lateral magnification of the focusing lens group located closer to the object side than the focusing lens group closest to the image among the focusing lens groups included in the subsequent lens groups when focusing on an object at infinity in the wide-angle end state. βF2w indicates the lateral magnification of the focusing lens group closest to the image among the focusing lens groups included in the subsequent lens groups when focusing on an object at infinity in the wide-angle end state. βF1t indicates the combined lateral magnification of the focusing lens group located closer to the object than the focusing lens group closest to the image among the focusing lens groups included in the subsequent lens group when focusing on an object at infinity in the telephoto end state. βF2t indicates the lateral magnification of the focusing lens group located closest to the image among the focusing lens groups included in the subsequent lens group when focusing on an object at infinity in the telephoto end state. fN indicates the focal length of the second lens located from the image side of the variable magnification optical system. fL indicates the focal length of the lens located closest to the image side of the variable magnification optical system. fRw indicates the focal length of the subsequent lens group in the wide-angle end state.

[0083] In the [Lens specifications] table, the surface number indicates the order of the optical surfaces from the object side along the direction of light travel, R is the radius of curvature of each optical surface (surfaces whose center of curvature is located on the image side are given a positive value), D is the surface spacing which is the distance on the optical axis from each optical surface to the next optical surface (or image surface), nd is the refractive index of the material of the optical component with respect to the d-line, and νd is the Abbe number based on the d-line of the material of the optical component. The "∞" in the radius of curvature indicates a plane or an aperture, and (stop S) indicates the aperture stop S. The refractive index of air, nd=1.00000, has been omitted. If the optical surface is aspheric, an * is added to the surface number, and the paraxial radius of curvature is shown in the column for radius of curvature R.

[0084] In the [Aspherical Data] table, the shape of the aspherical surface shown in [Lens Specifications] is shown by the following formula (A). X(y) is the distance (sag amount) along the optical axis direction from the tangent plane at the apex of the aspherical surface to the position on the aspherical surface at height y, R is the radius of curvature of the reference sphere (paraxial radius of curvature), κ is the conic constant, and Ai is the ith aspherical coefficient. "En" is the ratio of "×10 -n For example, 1.234E-05=1.234×10 -5 In addition, the second-order aspheric coefficient A2 is 0, and is omitted.

[0085] 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)

[0086] The [Variable Distance Data] table shows the surface spacing for surface number i, which has a surface spacing of (Di) in the [Lens Specifications] table. The [Variable Distance Data] table also shows the surface spacing when focused at infinity and when focused at close range.

[0087] The [Lens Group Data] table shows the starting surface (the surface closest to the object) and focal length of each lens group.

[0088] In the following, for all specifications, the focal length f, radius of curvature R, surface separation D, and other lengths are generally in "mm" unless otherwise specified; however, this is not limited to this because the optical system can provide the same optical performance even when proportionally enlarged or reduced.

[0089] The above explanation of the tables is common to all the embodiments, and therefore, duplicate explanations will be omitted below.

[0090] (First embodiment) The first embodiment will be described with reference to FIGS. 1 to 3 and Table 1. FIG. 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 is composed 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, which are arranged in order from the object side along the optical axis. When changing magnification from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move toward the object side along the optical axis, and the interval between each of the adjacent lens groups changes. The aperture stop S is disposed between the second lens group G2 and the third lens group G3. During magnification change, the aperture stop 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 the lens group, and this is the same in all the following embodiments.

[0091] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens consisting 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, and a positive meniscus lens L13 with a convex surface facing the object side.

[0092] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting 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, and a negative meniscus lens L24 with a concave surface facing the object side. The lens surface facing the object side of the negative meniscus lens L21 is aspheric.

[0093] The third lens group G3 is composed of a biconvex positive lens L31, the lens surface of which facing the object side is aspheric.

[0094] The fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42, a cemented positive lens of a biconvex positive lens L43 and a negative meniscus lens L44 with a concave surface facing the object side, and a positive meniscus lens L45 with a concave surface facing the object side. The lens surface facing the object side of the positive meniscus lens L45 is aspheric.

[0095] The fifth lens group G5 is composed of, arranged in order from the object side along the optical axis, a positive meniscus lens L51 with a concave surface facing the object side, and a biconcave negative lens L52.

[0096] The sixth lens group G6 is composed of a biconcave negative lens L61, the lens surface of which facing the object side is aspheric.

[0097] The seventh lens group G7 is composed of a positive meniscus lens L71 with a convex surface facing the object side. An image surface I is disposed on the image side of the seventh lens group G7.

[0098] In this embodiment, the first lens group G1 constitutes the front lens group GA having positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1 having negative refractive power. The third lens group G3 and the fourth lens group G4 constitute the second intermediate lens group GM2 having positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 constitute the rear lens group GR having negative refractive power as a whole. When focusing from an infinite object to a close object, the fifth lens group G5 and the sixth lens group G6 constituting the rear lens group GR move toward the image side along the optical axis with different trajectories (movement amounts). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1 arranged closest to the object side of the rear lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1.

[0099] Table 1 below lists the values ​​of the specifications of the variable magnification optical system according to the first example.

[0100] (Table 1) [Overall Specifications] Magnification 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 W M T 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 [Lens Specifications] Surface number R D 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 Close focus WMT 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

[0101] FIG. 2(A) is a diagram showing various aberrations when the variable magnification optical system according to the first embodiment is focused on infinity in the wide-angle end state. FIG. 2(B) is a diagram showing various aberrations when the variable magnification optical system according to the first embodiment is focused on infinity in the telephoto end state. FIG. 3(A) is a diagram showing various aberrations when the variable magnification optical system according to the first embodiment is focused on a close distance in the wide-angle end state. FIG. 3(B) is a diagram showing various aberrations when the variable magnification optical system according to the first embodiment is focused on a close distance in the telephoto end state. In each aberration diagram when focusing on infinity, FNO indicates the F-number, and Y indicates the image height. In each aberration diagram when focusing on a close distance, NA indicates the numerical aperture, and Y indicates the image height. In the spherical aberration diagram, the F-number or numerical aperture value corresponding to the maximum aperture is shown, in the astigmatism diagram and the distortion diagram, the maximum value of the image height is shown, and in the coma aberration diagram, the value of each image height is shown. d indicates the d-line (wavelength λ=587.6 nm), and g indicates the g-line (wavelength λ=435.8 nm). In the astigmatism diagrams, the solid line indicates the sagittal image surface, and the dashed line indicates the meridional image surface. Note that in the aberration diagrams of the following examples, the same symbols as in this example are used, and duplicated explanations will be omitted.

[0102] It can be seen from each of the aberration diagrams that the variable magnification optical system of Example 1 has excellent imaging performance, with various aberrations being well corrected not only when focusing at infinity but also when focusing at close distances, from the wide-angle end state to the telephoto end state.

[0103] (Second Example) The second embodiment will be described with reference to FIGS. 4 to 6 and Table 2. FIG. 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 is composed 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, which are arranged in order from the object side along the optical axis. When changing magnification from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move toward the object side along the optical axis, and the interval between the adjacent lens groups changes. The aperture stop S is disposed between the second lens group G2 and the third lens group G3. During magnification change, the aperture stop S moves along the optical axis together with the third lens group G3.

[0104] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens consisting 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, and a positive meniscus lens L13 with a convex surface facing the object side.

[0105] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting of a biconcave negative lens L22 and a biconvex positive lens L23, and a negative meniscus lens L24 with a concave surface facing the object side. The lens surface facing the object side of the negative meniscus lens L21 is aspheric.

[0106] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a positive meniscus lens L31 with a convex surface facing the object side, a biconvex positive lens L32, a cemented positive lens consisting of a negative meniscus lens L33 with a convex surface facing the object side and a biconvex positive lens L34, and a negative meniscus lens L35 with a concave surface facing the object side.

[0107] The fourth lens group G4 is composed of a cemented positive lens made up of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42.

[0108] The fifth lens group G5 is composed of, in order from the object side along the optical axis, a biconcave negative lens L51, a biconvex positive lens L52, and a cemented positive lens of a negative meniscus lens L53 with its concave surface facing the object side. The lens surface facing the image side of the negative meniscus lens L53 is aspheric.

[0109] The sixth lens group G6 is composed of a biconcave negative lens L61, the lens surface of which facing the object side is aspheric.

[0110] The seventh lens group G7 is composed of a biconvex positive lens L71. An image surface I is disposed on the image side of the seventh lens group G7.

[0111] In this embodiment, the first lens group G1 constitutes the front lens group GA having positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1 having negative refractive power. The third lens group G3 and the fourth lens group G4 constitute the second intermediate lens group GM2 having positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 constitute the rear lens group GR having negative refractive power as a whole. When focusing from an infinite object to a close object, the fifth lens group G5 constituting the rear lens group GR moves toward the object side along the optical axis, and the sixth lens group G6 constituting the rear lens group GR moves toward the image side along the optical axis. That is, the fifth lens group G5 corresponds to the first focusing lens group GF1 arranged closest to the object side of the rear lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1.

[0112] Table 2 below lists the values ​​of the specifications of the variable magnification optical system according to the second example.

[0113] (Table 2) [Overall specifications] Magnification 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] Surface 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 Close focus WMT 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

[0114] FIG. 5(A) is a diagram showing various aberrations of the variable magnification optical system according to the second example when focusing on infinity in the wide-angle end state. FIG. 5(B) is a diagram showing various aberrations of the variable magnification optical system according to the second example when focusing on infinity in the telephoto end state. FIG. 6(A) is a diagram showing various aberrations of the variable magnification optical system according to the second example when focusing on a close distance in the wide-angle end state. FIG. 6(B) is a diagram showing various aberrations of the variable magnification optical system according to the second example when focusing on a close distance in the telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system according to the second example has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the telephoto end state not only when focusing on infinity but also when focusing on a close distance.

[0115] (Third Example) The third embodiment will be described with reference to FIGS. 7 to 9 and Table 3. FIG. 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 is composed 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, which are arranged in order from the object side along the optical axis. When changing magnification from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move toward the object side along the optical axis, and the interval between each of the adjacent lens groups changes. The aperture stop S is disposed between the second lens group G2 and the third lens group G3. During magnification change, the aperture stop S moves along the optical axis together with the third lens group G3.

[0116] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens consisting of a plano-concave negative lens L11 with its flat surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 with its convex surface facing the object side.

[0117] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting of a biconcave negative lens L22 and a biconvex positive lens L23, and a plano-concave negative lens L24 with a flat surface facing the image side. The lens surface facing the object side of the negative meniscus lens L21 is aspheric.

[0118] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a positive meniscus lens L31 with a convex surface facing the object side, a biconvex positive lens L32, and a negative meniscus lens L33 with a concave surface facing the object side. The lens surface facing the object side of the positive meniscus lens L31 is aspheric.

[0119] The fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L41, and a cemented positive lens of a negative meniscus lens L42 with its convex surface facing the object side and a biconvex positive lens L43.

[0120] The fifth lens group G5 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L51 with a concave surface facing the object side, and a biconvex positive lens L52.

[0121] The sixth lens group G6 is composed of a positive meniscus lens L61 having a concave surface facing the object side, the lens surface facing the image side of which is aspheric.

[0122] The seventh lens group G7 is composed of, arranged in order from the object side along the optical axis, a negative biconcave lens L71 and a positive meniscus lens L72 with a convex surface facing the object side. An image surface I is disposed 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 having positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1 having negative refractive power. The third lens group G3 and the fourth lens group G4 constitute the second intermediate lens group GM2 having positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 constitute the rear lens group GR having negative refractive power as a whole. When focusing from an infinite object to a close object, the fifth lens group G5 and the sixth lens group G6 constituting the rear lens group GR move toward the object side along the optical axis with different trajectories (movement amounts). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1 arranged closest to the object side of the rear lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1.

[0124] Table 3 below lists the values ​​of the specifications of the variable magnification optical system according to the third example.

[0125] (Table 3) [Overall specifications] Magnification 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] Surface number RD nd νd Object plane ∞ 1∞2.0001.8466623.80 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

[0126] Fig. 8(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 3 when focusing on infinity in the wide-angle end state. Fig. 8(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 3 when focusing on infinity in the telephoto end state. Fig. 9(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 3 when focusing on a close distance in the wide-angle end state. Fig. 9(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 3 when focusing on a close distance in the telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system according to Example 3 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the telephoto end state not only when focusing on infinity but also when focusing on a close distance.

[0127] (Fourth Example) The fourth embodiment will be described with reference to FIGS. 10 to 12 and Table 4. FIG. 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 is composed 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, which are arranged in order from the object side along the optical axis. When changing magnification from the wide-angle end state (W) to the telephoto end state (T), the first to sixth lens groups G1 to G6 move toward the object side along the optical axis, and the seventh lens group G7 moves toward the object side once along the optical axis and then moves toward the image side, changing the interval between the adjacent lens groups. The aperture diaphragm S is disposed between the second lens group G2 and the third lens group G3. During magnification change, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0128] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens consisting 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, and a positive meniscus lens L13 with a convex surface facing the object side.

[0129] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting 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, and a biconcave negative lens L24. The lens surface facing the object side of the negative meniscus lens L21 is aspheric.

[0130] The third lens group G3 is composed of a positive meniscus lens L31 having a convex surface facing the object side, and a positive meniscus lens L32 having a convex surface facing the object side. The lens surface facing the object side of the positive meniscus lens L31 is aspheric.

[0131] The fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42, a cemented negative lens of a biconvex positive lens L43 and a negative meniscus lens L44 with a concave surface facing the object side, and a positive meniscus lens L45 with a concave surface facing the object side. The lens surface facing the object side of the positive meniscus lens L45 is aspheric.

[0132] The fifth lens group G5 is composed of a biconvex positive lens L51 and a biconcave negative lens L52, arranged in order from the object side along the optical axis.

[0133] The sixth lens group G6 is composed of a biconcave negative lens L61, the lens surface of which facing the object side is aspheric.

[0134] The seventh lens group G7 is composed of a positive meniscus lens L71 with a convex surface facing the object side. An image surface I is disposed 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 having positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1 having negative refractive power. The third lens group G3 and the fourth lens group G4 constitute the second intermediate lens group GM2 having positive refractive power as a whole. The fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 constitute the rear lens group GR having negative refractive power as a whole. When focusing from an infinite object to a close object, the fifth lens group G5 and the sixth lens group G6 constituting the rear lens group GR move toward the image side along the optical axis with different trajectories (movement amounts). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1 arranged closest to the object side of the rear lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1.

[0136] Table 4 below lists the values ​​of the specifications of the variable magnification optical system according to the fourth example.

[0137] (Table 4) [Overall specifications] Magnification 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] Surface 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 plane 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

[0138] Fig. 11(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 4 when focusing on infinity in the wide-angle end state. Fig. 11(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 4 when focusing on infinity in the telephoto end state. Fig. 12(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 4 when focusing on a close distance in the wide-angle end state. Fig. 12(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 4 when focusing on a close distance in the telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system according to Example 4 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the telephoto end state not only when focusing on infinity but also when focusing on a close distance.

[0139] (Fifth Example) 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 variable magnification optical system according to the fifth embodiment. The variable magnification optical system ZL(5) according to the fifth embodiment is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having negative 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, a seventh lens group G7 having negative refractive power, and an eighth lens group G8 having positive refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move toward the object side along the optical axis, and the eighth lens group G8 moves toward the object side along the optical axis once and then toward the image side, changing the interval between adjacent lens groups. The aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4. When changing the magnification, the aperture diaphragm S moves along the optical axis together with the fourth lens group G4.

[0140] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens consisting 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, and a positive meniscus lens L13 with a convex surface facing the object side.

[0141] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a biconcave negative lens L21, a cemented positive lens consisting 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 lens surface facing the object side of the negative lens L21 is aspheric.

[0142] The third lens group G3 is composed of a biconcave negative lens L31.

[0143] The fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, 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. The lens surface facing the object side of the positive meniscus lens L41 is aspheric.

[0144] The fifth lens group G5 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L51 with a convex surface facing the object side and a biconvex positive lens L52, a cemented negative lens of a positive meniscus lens L53 with a concave surface facing the object side and a negative meniscus lens L54 with a concave surface facing the object side, and a positive meniscus lens L55 with a concave surface facing the object side. The lens surface facing the object side of the positive meniscus lens L55 is aspheric.

[0145] The sixth lens group G6 is composed of a biconvex positive lens L61 and a biconcave negative lens L62, arranged in order from the object side along the optical axis.

[0146] The seventh lens group G7 is composed of a biconcave negative lens L71, the lens surface of which facing the object side is aspheric.

[0147] The eighth lens group G8 is composed of a positive meniscus lens L81 with a convex surface facing the object side. An image surface I is disposed on the image side of the eighth lens group G8.

[0148] In this embodiment, the first lens group G1 constitutes the front lens group GA having positive refractive power. The second lens group G2 and the third lens group G3 constitute the first intermediate lens group GM1 having negative refractive power as a whole. The fourth lens group G4 and the fifth lens group G5 constitute the second intermediate lens group GM2 having positive refractive power as a whole. The sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 constitute the rear lens group GR having negative refractive power as a whole. When focusing from an infinite object to a close object, the sixth lens group G6 and the seventh lens group G7 constituting the rear lens group GR move toward the image side along the optical axis with different trajectories (movement amounts). That is, the sixth lens group G6 corresponds to the first focusing lens group GF1 arranged closest to the object side of the rear lens group GR. The seventh lens group G7 corresponds to the second focusing lens group GF2, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1.

[0149] Table 5 below lists the values ​​of the specifications of the variable magnification optical system according to the fifth example.

[0150] (Table 5) [Overall specifications] Magnification 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] Surface 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 ∞ [Aspheric data] Page 6 κ=1.0000,A4=6.01924E-06,A6=-9.78216E-09,A8=1.91188E-11,A10=-2.54581E-14 Side 14 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

[0151] Fig. 14(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 5 when focusing on infinity in the wide-angle end state. Fig. 14(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 5 when focusing on infinity in the telephoto end state. Fig. 15(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 5 when focusing on a close distance in the wide-angle end state. Fig. 15(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 5 when focusing on a close distance in the telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system according to Example 5 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the telephoto end state not only when focusing on infinity but also when focusing on a close distance.

[0152] (Sixth Example) The sixth embodiment will be described with reference to FIGS. 16 to 18 and Table 6. FIG. 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 is composed 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, which are arranged in order from the object side along the optical axis. When changing magnification from the wide-angle end state (W) to the telephoto end state (T), the first to eighth lens groups G1 to G8 move toward the object side along the optical axis, and the intervals between the adjacent lens groups change. The aperture diaphragm S is disposed between the second lens group G2 and the third lens group G3. During magnification change, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0153] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens consisting of a negative meniscus lens L11 with a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 with a convex surface facing the object side.

[0154] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens of a biconcave negative lens L22 and a biconvex positive lens L23, and a biconcave negative lens L24. The lens surface facing the object side of the negative meniscus lens L21 is aspheric.

[0155] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a positive meniscus lens L31 with a convex surface facing the object side, a biconvex positive lens L32, and a negative meniscus lens L33 with a concave surface facing the object side. The lens surface facing the object side of the positive meniscus lens L31 is aspheric.

[0156] The fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L41, and a cemented negative lens consisting of a negative meniscus lens L42 with its convex surface facing the object side and a biconvex positive lens L43.

[0157] The fifth lens group G5 is composed of a negative meniscus lens L51 with its concave surface facing the object side.

[0158] The sixth lens group G6 is composed of a biconvex positive lens L61.

[0159] The seventh lens group G7 is composed of a positive meniscus lens L71 with a concave surface facing the object side. The lens surface facing the image side of the positive meniscus lens L71 is aspheric.

[0160] The eighth lens group G8 is composed of, arranged in order from the object side along the optical axis, a biconcave negative lens L81 and a positive meniscus lens L82 with its convex surface facing the object side. An image surface I is disposed on the image side of the eighth lens group G8.

[0161] In this embodiment, the first lens group G1 constitutes the front lens group GA having positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1 having negative refractive power. The third lens group G3 and the fourth lens group G4 constitute the second intermediate lens group GM2 having 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 constitute the rear lens group GR having negative refractive power as a whole. When focusing from an object at infinity to an object at close range, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 constituting the rear lens group GR move toward the object side along the optical axis with different trajectories (movement amounts). That is, the fifth lens group G5 corresponds to the first focusing lens group GF1 arranged closest to the object side of the rear lens group GR. The sixth lens group G6 corresponds to the second focusing lens group GF2, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1, and the seventh lens group G7 corresponds to the third focusing lens group GF3, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1.

[0162] Table 6 below lists the values ​​of the specifications of the variable magnification optical system according to the sixth example.

[0163] (Table 6) [Overall specifications] Magnification 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] Surface 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

[0164] Fig. 17(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 6 when focusing on infinity in the wide-angle end state. Fig. 17(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 6 when focusing on infinity in the telephoto end state. Fig. 18(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 6 when focusing on a close distance in the wide-angle end state. Fig. 18(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 6 when focusing on a close distance in the telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system according to Example 6 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the telephoto end state not only when focusing on infinity but also when focusing on a close distance.

[0165] (Seventh Example) The seventh embodiment will be described with reference to FIGS. 19 to 21 and Table 7. FIG. 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 is composed 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, which are arranged in order from the object side along the optical axis. When changing magnification from the wide-angle end state (W) to the telephoto end state (T), the first to eighth lens groups G1 to G8 move toward the object side along the optical axis, and the intervals between the adjacent lens groups change. The aperture diaphragm S is disposed between the second lens group G2 and the third lens group G3. During magnification change, the aperture diaphragm S moves along the optical axis together with the third lens group G3.

[0166] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens consisting of a negative meniscus lens L11 with a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 with a convex surface facing the object side.

[0167] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting of a biconcave negative lens L22 and a biconvex positive lens L23, and a plano-concave negative lens L24 with a flat surface facing the image side. The lens surface facing the object side of the negative meniscus lens L21 is aspheric.

[0168] The third lens group G3 is composed of a biconvex positive lens L31 and a biconvex positive lens L32, arranged in order from the object side along the optical axis. The object side lens surface of the positive lens L31 is aspheric.

[0169] The fourth lens group G4 is composed of a biconcave negative lens L41.

[0170] The fifth lens group G5 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L51, and a cemented positive lens of a negative meniscus lens L52 with its convex surface facing the object side and a biconvex positive lens L53.

[0171] The sixth lens group G6 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L61 with a concave surface facing the object side, and a biconvex positive lens L62.

[0172] The seventh lens group G7 is composed of a positive meniscus lens L71 with a concave surface facing the object side. The lens surface facing the image side of the positive meniscus lens L71 is aspheric.

[0173] The eighth lens group G8 is composed of, arranged in order from the object side along the optical axis, a biconcave negative lens L81 and a positive meniscus lens L82 with its convex surface facing the object side. An image surface I is disposed on the image side of the eighth lens group G8.

[0174] In this embodiment, the first lens group G1 constitutes the front lens group GA having positive refractive power. The second lens group G2 constitutes the first intermediate lens group GM1 having negative refractive power. The third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the second intermediate lens group GM2 having positive refractive power as a whole. The sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 constitute the rear lens group GR having negative refractive power as a whole. When focusing from an infinite object to a close object, the sixth lens group G6 and the seventh lens group G7 constituting the rear lens group GR move toward the object side along the optical axis with different trajectories (movement amounts). That is, the sixth lens group G6 corresponds to the first focusing lens group GF1 arranged closest to the object side of the rear lens group GR. The seventh lens group G7 corresponds to the second focusing lens group GF2, which is another focusing lens group arranged closer to the image side than the first focusing lens group GF1.

[0175] Table 7 below lists the values ​​of the specifications of the variable magnification optical system according to the seventh example.

[0176] (Table 7) [Overall specifications] Magnification 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] Surface 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 Close focus WMT 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

[0177] Fig. 20(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 7 when focusing on infinity in the wide-angle end state. Fig. 20(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 7 when focusing on infinity in the telephoto end state. Fig. 21(A) is a diagram showing various aberrations of the variable magnification optical system according to Example 7 when focusing on a close distance in the wide-angle end state. Fig. 21(B) is a diagram showing various aberrations of the variable magnification optical system according to Example 7 when focusing on a close distance in the telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system according to Example 7 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the telephoto end state not only when focusing on infinity but also when focusing on a close distance.

[0178] Next, a table of [Values ​​Corresponding to Conditional Expressions] is shown below. This table shows the values ​​corresponding to each of the conditional expressions (1) to (18) for all the examples (Examples 1 to 7). Condition (1) -6.00 <fFs / fw<6.00 Condition (2) 2.00 <f1 / fw<8.00 Condition (3) 0.10 <BFw / fw<1.00 Conditional expression (4) 0.20<|fFs| / f1<2.00 Conditional expression (5) 1.50<|fFs| / (-fM1w)<5.00 Conditional expression (6) 0.90<|fFs| / fM2w<4.00 Condition (7) 0.20 <f1 / (-fRw)<5.00 Condition (8) 0.10 <MTF1 / MTF2<3.00 Conditional expression (9) 0.10<βF1w / βF2w<3.00 Conditional expression (10) 0.10<βF1t / βF2t<3.00 Condition (11) 0.50<βF1w<2.60 Conditional expression (12) 0.20<βF2w<1.80 Conditional expression (13) {βF1w+(1 / βF1w)} -2 ≦0.25 Conditional expression (14) {βF2w+(1 / βF2w)} -2 ≦0.25 Conditional expression (15) 0.10<|fFs| / |fRF|<4.00 Conditional expression (16) 2ωw>75.0° Condition (17) ft / fw>3.50 Conditional expression (18) 0.10<(-fN) / fL<1.00

[0179] [Conditional Expression Corresponding Values] (First to Fourth Examples) Conditional Expression 1st Example 2nd Example 3rd Example 4th Example (1) -1.547 -1.279 3.722 -1.457 (2) 3.932 4.500 6.953 4.181 (3) 0.555 0.464 0.507 0.504 (4) 0.393 0.284 0.535 0.349 (5) 2.165 1.852 4.005 2.010 (6) 1.281 1.087 2.511 1.208 (7) 2.094 1.822 0.991 2.321 (8) 0.407 0.284 1.442 0.432 (9) 0.679 0.626 0.807 0.644 (10) 0.359 0.263 0.695 0.282 (11) 1.071 1.045 0.770 1.005 (12) 1.577 1.670 0.954 1.561 (13) 0.249 0.250 0.234 0.250 (14) 0.205 0.194 0.249 0.206 (15) 0.296 0.402 1.922 0.211 (16) 85.22 85.22 91.54 85.20 (17) 4.737 4.737 4.558 7.854 (18) 0.296 0.402 0.303 0.211 [Conditional Expression Corresponding Values] (Fifth to Seventh Examples) Conditional Expression 5th Example 6th Example 7th Example (1) -1.479 1.758 3.742 (2) 4.123 5.440 6.806 (3) 0.504 0.500 0.521 (4) 0.359 0.323 0.550 (5) 2.112 2.182 4.154 (6) 1.246 1.333 2.537 (7) 2.280 0.707 0.868 (8) 0.391 1.073 1.403 (9) 0.647 0.806 0.805 (10) 0.283 0.725 0.692 (11) 1.002 0.765 0.763 (12) 1.550 0.949 0.948 (13) 0.250 0.233 0.233 (14) 0.208 0.249 0.249 (15) 0.203 0.917 1.880 (16) 85.20 86.44 91.56 (17) 7.854 4.696 4.558 (18) 0.203 0.213 0.300

[0180] According to each of the above embodiments, by making the focusing lens group small and lightweight, it is possible to realize quiet and high-speed focusing without increasing the size of the lens barrel. Also, it is possible to realize a variable magnification optical system with little aberration fluctuation when changing the magnification from the wide-angle end state to the telephoto end state and when focusing from an object at infinity to a close object.

[0181] The above-mentioned embodiments are merely examples of the present invention, and the present invention is not limited to these.

[0182] The following contents can be appropriately adopted within a range that does not impair the optical performance of the variable magnification optical system of this embodiment.

[0183] Although seven and eight group configurations have been shown as examples of the variable magnification optical system of this embodiment, the present application is not limited thereto, and a variable magnification optical system of other group configurations (e.g., nine groups, etc.) can also be configured. Specifically, a lens or lens group may be added to the most object side or the most image side of the variable magnification optical system of this embodiment. Note that a lens group refers to a portion having at least one lens separated by an air gap that changes when the magnification is changed.

[0184] A single or multiple lens groups, or a partial lens group, may be moved in the optical axis direction to function as a focusing lens group that focuses from an object at infinity to an object at a close distance. The focusing lens group can also be applied to autofocusing, and is suitable for driving a motor (using an ultrasonic motor, etc.) for autofocusing.

[0185] The lens group or partial lens group may be moved so as to have a component in a direction perpendicular to the optical axis, or may be rotated (rocked) in a plane including the optical axis to serve as an anti-vibration lens group that corrects image blur caused by camera shake.

[0186] The lens surface may be spherical or flat, or aspherical. A spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment, and prevents deterioration of optical performance due to errors in processing and assembly adjustment. It is also preferable because there is little deterioration in image quality even if the image plane is shifted.

[0187] When the lens surface is aspheric, the aspheric surface may be any of the following: an aspheric surface formed by grinding, a glass molded aspheric surface formed by molding glass into an aspheric shape, or a composite aspheric surface formed by molding a resin into an aspheric shape on the surface of glass. The lens surface may also be a diffractive surface, or the lens may be a gradient index lens (GRIN lens) or a plastic lens.

[0188] It is preferable that the aperture diaphragm be located between the second lens group and the third lens group, or between the third lens group and the fourth lens group, but it is also possible to use the lens frame to fulfill this role instead of providing a component serving as an aperture diaphragm.

[0189] Each lens surface may be coated with an anti-reflection coating having high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high-contrast optical performance. [Explanation of symbols]

[0190] G1 1st lens group G2 2nd 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 stop

Claims

1. the first lens group having a positive refractive power, the second lens group having a negative refractive power, an intermediate lens group having a positive refractive power and consisting of three or less lens groups, and a subsequent lens group, arranged in order from the object side along the optical axis; the subsequent lens group is composed of, arranged in order from the object side, a first focusing lens group having negative refractive power and moving along the optical axis during focusing, a second focusing lens group having negative refractive power and moving along the optical axis along a locus different from that of the first focusing lens group during focusing, and a final lens group having positive refractive power; When changing magnification, the spacing between adjacent lens groups changes, During focusing, the first focusing lens group and the second focusing lens group move in the same direction along the optical axis, the second focusing lens group is composed of one single lens, A variable magnification optical system that satisfies the following condition: -6.00<fFs / fw<6.00 where fFs is the focal length of the focusing lens group having the strongest refractive power among the first focusing lens group and the second focusing lens group. fw: focal length of the variable magnification optical system in the wide-angle end state

2. A variable magnification optical system as described in claim 1, which satisfies the following conditional expression. 2.00<f1 / fw<8.00 where f1 is the focal length of the first lens group.

3. A variable magnification optical system as described in claim 1 or 2, which satisfies the following conditional expression. 0.10<BFw / fw<1.00 where BFw is the back focus of the variable magnification optical system in the wide-angle end state.

4. A variable magnification optical system described in any one of claims 1 to 3, which satisfies the following conditional expression. 0.20<|fFs| / f1<2.00 where f1 is the focal length of the first lens group.

5. A variable magnification optical system described in any one of claims 1 to 4, which satisfies the following conditional expression. 0.90<|fFs| / fM2w<4.00 where fM2w is the focal length of the intermediate lens group in the wide-angle end state.

6. A variable magnification optical system described in any one of claims 1 to 5, which satisfies the following conditional expression. 0.20<f1 / (-fRw)<5.00 where f1 is the focal length of the first front lens group. fRw: focal length of the rear lens group in the wide-angle end state

7. A variable magnification optical system described in any one of claims 1 to 6, which satisfies the following conditional expression. 0.10<MTF1 / MTF2<3.00 However, MTF1: absolute value of the movement amount of the first focusing lens group MTF2: Absolute value of the movement amount of the second focusing lens group

8. A variable magnification optical system according to any one of claims 1 to 7, which satisfies the following conditional expression. 0.10<βF1w / βF2w<3.00 where βF1w is the lateral magnification of the first focusing lens group when focused on an object at infinity in the wide-angle end state. βF2w: lateral magnification of the second focusing lens group when focused on an object at infinity in the wide-angle end state

9. A variable magnification optical system according to any one of claims 1 to 8, which satisfies the following conditional expression. 0.10<βF1t / βF2t<3.00 where βF1t is the lateral magnification when the first focusing lens group is in the telephoto end state and focused on an object at infinity. βF2t: lateral magnification of the second focusing lens group when focused on an object at infinity in the telephoto end state

10. A variable magnification optical system according to any one of claims 1 to 9, which satisfies the following conditional expression: 0.50<βF1w<2.60 where βF1w is the lateral magnification when the first focusing lens is in the wide-angle end state and focused on an object at infinity.

11. A variable magnification optical system according to any one of claims 1 to 10, which satisfies the following conditional expression. 0.20<βF2w<1.80 where βF2w is the lateral magnification when the second focusing lens group is in the wide-angle end state and focused on an object at infinity.

12. A variable magnification optical system according to any one of claims 1 to 11, which satisfies the following conditional expression: {βF1w+(1 / βF1w)} -2 ≦0.25 where βF1w is the lateral magnification when the first focusing lens is in the wide-angle end state and focused on an object at infinity.

13. A variable magnification optical system according to any one of claims 1 to 12, which satisfies the following conditional expression: {βF2w+(1 / βF2w)} -2 ≦0.25 where βF2w is the lateral magnification when the second focusing lens group is in the wide-angle end state and focused on an object at infinity.

14. A variable magnification optical system according to any one of claims 1 to 13, which satisfies the following conditional expression: 0.10<|fFs| / |fRF|<4.00 where fRF is the focal length of the final lens group.

15. A variable magnification optical system according to any one of claims 1 to 14, which satisfies the following conditional expression: 2ωw>75.0° where 2ωw is the total angle of view of the variable magnification optical system in the wide-angle end state.

16. A variable magnification optical system according to any one of claims 1 to 15, which satisfies the following conditional expression: ft / fw>3.50 where ft is the focal length of the variable magnification optical system in the telephoto end state.

17. A variable magnification optical system according to any one of claims 1 to 16, which satisfies the following conditional expression: 0.10<(-fN) / fL<1.00 where fN is the focal length of the second lens located from the image side of the variable magnification optical system. fL: the focal length of the lens located closest to the image side of the variable magnification optical system

18. An optical instrument comprising a variable magnification optical system according to any one of claims 1 to 17.

Images