Zoom optical system, optical device, and method of manufacturing zoom optical system

Abstract

To provide a zoom optical system which is compact and yet offers good optical performance.SOLUTION: A zoom optical system ZL provided herein consists of a first lens group G1 having negative refractive power and a rear group GR comprising at least one lens group, and is configured such that distances between adjacent lens groups change while zooming. At least a part of a lens group belonging to the rear group GR is a focusing group GF with positive refractive power configured to move along an optical axis while focusing. The zoom optical system satisfies the following conditional expression: 0.50<ft / fF<10.00, where ft represents a focal length of the zoom optical system ZL at the telephoto end, and fF represents a focal length of the focusing group GF.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Variable magnification optical systems suitable for photo cameras, electronic still cameras, video cameras, etc. have been proposed in the past (see, for example, Patent Document 1). However, it is difficult to achieve good optical performance while making such variable magnification optical systems compact. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 012638 Summary of the Invention

[0004] A variable magnification optical system according to the present invention comprises, arranged in order from the object side along an optical axis, a first lens group having negative refractive power and a rear group having at least one lens group, wherein the spacing between adjacent lens groups changes during magnification variation, and at least a portion of any of the at least one lens group in the rear group is a focusing group having positive refractive power that moves along the optical axis during focusing, and satisfies the following conditional expression: 0.30 <fw / fF<7.00 where fw is the focal length of the variable magnification optical system in the wide-angle end state fF: focal length of the focusing group

[0005] An optical apparatus according to the present invention is configured to include the variable magnification optical system described above.

[0006] A second manufacturing method of a variable magnification optical system according to the present invention is a manufacturing method of a variable magnification optical system consisting of a first lens group having negative refractive power and a rear group having at least one lens group, arranged in order from the object side along the optical axis, wherein the spacing between adjacent lens groups changes during magnification variation, and at least a portion of any of the lens groups in the at least one lens group in the rear group is a focusing group having positive refractive power that moves along the optical axis during focusing, and wherein each lens is arranged within the lens barrel so as to satisfy the following conditional expression: 0.30 <fw / fF<7.00 where fw is the focal length of the variable magnification optical system in the wide-angle end state fF: focal length of the focusing group [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing the lens configuration of a variable magnification optical system according to Example 1. [Figure 2] 2A and 2B are diagrams showing various aberrations of the variable magnification optical system according to Example 1 when focused at infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 3] FIG. 10 is a diagram showing the lens configuration of a variable magnification optical system according to Example 2. [Figure 4] 4A and 4B are diagrams showing various aberrations of the variable magnification optical system according to Example 2 when focused at infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 5] FIG. 10 is a diagram showing the lens configuration of a variable magnification optical system according to Example 3. [Figure 6] 6A and 6B are diagrams showing various aberrations of the variable magnification optical system according to Example 3 when focused at infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 7] FIG. 10 is a diagram showing the lens configuration of a variable magnification optical system according to Example 4. [Figure 8] 8A and 8B 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 9] FIG. 10 is a diagram showing the lens configuration of a variable magnification optical system according to Example 5. [Figure 10] 10A and 10B are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focused at infinity in the wide-angle end state and the telephoto end state, respectively. [Figure 11] 1 is a diagram showing the configuration of a camera equipped with a variable magnification optical system according to each embodiment. [Figure 12] 10 is a flowchart illustrating a method for manufacturing a variable magnification optical system according to each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present invention will now be described. First, a camera (optical device) equipped with a variable magnification optical system according to each embodiment will be described with reference to FIG. 11. As shown in FIG. 11, this camera 1 is composed of a main body 2 and a photographic lens 3 attached to the main body 2. The main body 2 includes an image sensor 4, a main body control unit (not shown) that controls the operation of the digital camera, and an LCD screen 5. The photographic lens 3 includes a variable magnification optical system ZL consisting of multiple 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, etc.

[0009] Light from the 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 LCD screen 5 in response to a user operation. Note that this camera may be a mirrorless camera or a single-lens reflex camera with a quick-return mirror. Also, the variable magnification optical system ZL shown in FIG. 11 is a schematic representation 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.

[0010] Next, a variable magnification optical system according to the first embodiment will be described. A variable magnification optical system ZL(1), which is an example of a variable magnification optical system (zoom lens) ZL according to the first embodiment, is composed of, as shown in FIG. 1, a first lens group G1 having negative refractive power and a rear group GR having at least one lens group, arranged in order from the object side along the optical axis. The spacing between adjacent lens groups changes during magnification. Furthermore, at least a portion of one of the lens groups in the at least one lens group in the rear group GR is a focusing group GF having positive refractive power that moves along the optical axis during focusing.

[0011] With the above-described configuration, the variable-magnification optical system ZL according to the first embodiment satisfies the following conditional expression (1). 0.50 <ft / fF<10.00 ···(1) where ft is the focal length of the variable magnification optical system ZL at the telephoto end fF: focal length of focusing group GF

[0012] According to the first embodiment, it is possible to obtain a variable magnification optical system that is small yet has good optical performance, and an optical device equipped with this variable magnification optical system. The variable magnification optical system ZL according to the first embodiment may be the variable magnification optical system ZL(2) shown in Fig. 3, the variable magnification optical system ZL(3) shown in Fig. 5, the variable magnification optical system ZL(4) shown in Fig. 7, or the variable magnification optical system ZL(5) shown in Fig. 9.

[0013] Conditional formula (1) defines the appropriate relationship between the focal length of the variable magnification optical system ZL at the telephoto end and the focal length of the focusing group GF. By satisfying conditional formula (1), it is possible to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on close objects, while still maintaining a compact size.

[0014] If the value corresponding to conditional expression (1) falls outside the above range, the amount of movement of the focusing group GF becomes large, making it difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. The effects of this embodiment can be further enhanced by setting the upper limit of conditional expression (1) to 8.50, 7.00, 6.00, 5.00, 4.50, 4.00, 3.50, 3.00, 2.75, 2.50, 2.25, or even 2.00. Furthermore, the effects of this embodiment can be further enhanced by setting the lower limit of conditional expression (1) to 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.90, 0.95, 1.00, 1.05, or even 1.10.

[0015] Next, a variable magnification optical system according to the second embodiment will be described. A variable magnification optical system ZL(1), which is an example of a variable magnification optical system (zoom lens) ZL according to the second embodiment, is composed of, as shown in FIG. 1, a first lens group G1 having negative refractive power and a rear group GR having at least one lens group, arranged in order from the object side along the optical axis. The spacing between adjacent lens groups changes during magnification. Furthermore, at least a portion of one of the lens groups in the rear group GR is a focusing group GF having positive refractive power that moves along the optical axis during focusing.

[0016] With the above-described configuration, the variable-magnification optical system ZL according to the second embodiment satisfies the following conditional expression (2). 0.30 <fw / fF<7.00 ···(2) where fw is the focal length of the variable magnification optical system ZL at the wide-angle end fF: focal length of focusing group GF

[0017] According to the second embodiment, it is possible to obtain a variable magnification optical system that is small yet has good optical performance, and an optical device equipped with this variable magnification optical system. The variable magnification optical system ZL according to the second embodiment may be the variable magnification optical system ZL(2) shown in Fig. 3, the variable magnification optical system ZL(3) shown in Fig. 5, the variable magnification optical system ZL(4) shown in Fig. 7, or the variable magnification optical system ZL(5) shown in Fig. 9.

[0018] Conditional expression (2) defines the appropriate relationship between the focal length of the variable magnification optical system ZL in the wide-angle end state and the focal length of the focusing group GF. By satisfying conditional expression (2), it is possible to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on close objects, while still maintaining a compact size.

[0019] If the value corresponding to conditional expression (2) falls outside the above range, the amount of movement of the focusing group GF becomes large, making it difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. The effects of this embodiment can be further enhanced by setting the upper limit of conditional expression (2) to 6.00, 5.00, 4.50, 4.00, 3.50, 3.00, 2.75, 2.50, 2.25, 2.00, 1.75, 1.50, or even 1.25. Furthermore, the effects of this embodiment can be further enhanced by setting the lower limit of conditional expression (2) to 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, or even 0.65.

[0020] In the variable magnification optical systems ZL according to the first and second embodiments, it is desirable that at least one lens group in the rear group GR includes a second lens group G2 having positive refractive power that is arranged closest to the object side of the rear group GR, and that the following conditional expression (3) be satisfied: 1.30 <f2 / (-X2)<2.50 ···(3) However, f2 is the focal length of the second lens group G2. X2: The amount of movement of the second lens group G2 when changing magnification from the wide-angle end state to the telephoto end state (the amount of movement toward the image side is taken as a positive value)

[0021] Conditional expression (3) defines an appropriate relationship between the focal length of the second lens group G2 and the amount of movement of the second lens group G2 when changing magnification from the wide-angle end state to the telephoto end state. By satisfying conditional expression (3), various aberrations can be effectively corrected despite the compact size.

[0022] If the value corresponding to conditional expression (3) falls outside the above range, it becomes difficult to correct various aberrations while miniaturizing the variable-magnification optical system ZL. By setting the upper limit of conditional expression (3) to 2.40, 2.30, 2.25, 2.20, 2.15, 2.10, or even 2.05, the effects of each embodiment can be more reliably achieved. Furthermore, by setting the lower limit of conditional expression (3) to 1.33, 1.35, 1.38, 1.40, or even 1.43, the effects of each embodiment can be more reliably achieved.

[0023] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (4). 1.00<βRt / βRw<2.25 (4) βRt: Lateral magnification of rear group GR at telephoto end βRw: Lateral magnification of rear group GR at the wide-angle end

[0024] Conditional expression (4) defines the appropriate relationship between the lateral magnification of the rear group GR in the maximum telephoto state and the lateral magnification of the rear group GR in the maximum wide-angle state. By satisfying conditional expression (4), it is possible to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on close objects, while maintaining a compact size.

[0025] If the value corresponding to conditional expression (4) falls outside the above range, it becomes difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. By setting the upper limit of conditional expression (4) to 2.20, 2.10, 2.00, 1.95, 1.90, or even 1.85, the effects of each embodiment can be further ensured. Furthermore, by setting the lower limit of conditional expression (4) to 1.05, 1.10, 1.15, 1.20, or even 1.25, the effects of each embodiment can be further ensured.

[0026] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (5). 0.30<(-fFRw) / fF<7.00 (5) where fFRw is the focal length of the lens group consisting of lenses arranged closer to the image than the focusing group GF in the wide-angle end state.

[0027] Conditional expression (5) defines an appropriate relationship between the focal length of the lens group composed of lenses arranged closer to the image than the focusing group GF in the wide-angle end state and the focal length of the focusing group GF. Hereinafter, the lens group composed of lenses arranged closer to the image than the focusing group GF may be referred to as the image-side lens group GFR. By satisfying conditional expression (5), it is possible to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on close objects, while maintaining a compact size.

[0028] If the corresponding value of conditional expression (5) exceeds the upper limit, the focal length of the focusing group GF becomes too short relative to the focal length of the image-side lens group GFR, making it difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. By setting the upper limit of conditional expression (5) to 6.00, 5.00, 4.50, 4.00, 3.50, 3.00, 2.75, 2.50, 2.25, 2.00, 1.75, 1.50, or even 1.30, the effects of each embodiment can be more reliably achieved.

[0029] If the corresponding value of conditional expression (5) falls below the lower limit, the amount of movement of the focusing group GF becomes large, making it difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. By setting the lower limit of conditional expression (5) to 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, or even 0.95, the effects of each embodiment can be further ensured.

[0030] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (6). 0.30<(-fFRt) / fF<7.00 (6) where fFRt is the focal length of the lens group that is composed of lenses that are arranged closer to the image than the focusing group GF in the telephoto end state.

[0031] Conditional expression (6) defines an appropriate relationship between the focal length of the lens group (image-side lens group GFR) composed of lenses arranged closer to the image than the focusing group GF in the maximum telephoto state, and the focal length of the focusing group GF. By satisfying conditional expression (6), it is possible to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on close objects, while maintaining a compact size.

[0032] If the corresponding value of conditional expression (6) exceeds the upper limit, the focal length of the focusing group GF becomes too short relative to the focal length of the image-side lens group GFR, making it difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. By setting the upper limit of conditional expression (6) to 6.00, 5.00, 4.50, 4.00, 3.75, 3.50, 3.00, 3.25, 3.00, 2.75, 2.50, or even 2.25, the effects of each embodiment can be more reliably achieved.

[0033] If the corresponding value of conditional expression (6) falls below the lower limit, the amount of movement of the focusing group GF becomes large, making it difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. By setting the lower limit of conditional expression (6) to 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.05, 1.10, or even 1.15, the effects of each embodiment can be further ensured.

[0034] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (7). 0.20 <fRPF / fF<3.00 ···(7) However, fRPF: the focal length of the lens group closest to the object that has positive refractive power among at least one lens group in the rear group GR.

[0035] Conditional expression (7) defines an appropriate relationship between the focal length of the focusing group GF and the focal length of the lens group having positive refractive power that is closest to the object, among at least one lens group in the rear group GR. By satisfying conditional expression (7), it is possible to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on close objects, even while maintaining a compact size.

[0036] If the corresponding value of conditional expression (7) exceeds the upper limit, the focal length of the focusing group GF becomes short, making it difficult to suppress fluctuations in spherical aberration, coma, and field curvature when focusing on a close object. By setting the upper limit of conditional expression (7) to 2.75, 2.50, 2.25, 2.00, 1.75, 1.50, 1.25, 1.00, 0.95, or even 0.90, the effects of each embodiment can be further ensured.

[0037] If the value corresponding to conditional expression (7) falls below the lower limit, the focal length of the lens group having positive refractive power in the rear group GR that is closest to the object becomes short, making it difficult to correct spherical aberration and coma. By setting the lower limit of conditional expression (7) to 0.25, 0.30, 0.35, 0.40, or even 0.45, the effects of each embodiment can be more reliably achieved.

[0038] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (8). 0.15 <fRw / fF<4.00 ···(8) where fRw is the focal length of the rear group GR at the wide-angle end

[0039] Condition (8) defines the appropriate relationship between the focal length of the rear group GR and the focal length of the focusing group GF at the maximum wide-angle position. By satisfying condition (8), various aberrations can be effectively corrected despite the compact size.

[0040] If the corresponding value of conditional expression (8) exceeds the upper limit, it becomes difficult to correct various aberrations while making the variable-magnification optical system ZL compact. By setting the upper limit of conditional expression (8) to 3.50, 3.00, 2.50, 2.00, 1.75, 1.50, 1.25, 1.15, or even 1.00, the effects of each embodiment can be further ensured. Furthermore, by setting the lower limit of conditional expression (8) to 0.20, 0.23, 0.25, 0.28, 0.30, 0.33, or even 0.35, the effects of each embodiment can be further ensured.

[0041] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (9). 0.15 <fRt / fF<5.00 ···(9) where fRt is the focal length of the rear group GR at the telephoto end

[0042] Condition (9) defines the appropriate relationship between the focal length of the rear group GR and the focal length of the focusing group GF at the maximum telephoto position. By satisfying condition (9), various aberrations can be effectively corrected despite the compact size.

[0043] If the corresponding value of conditional expression (9) exceeds the upper limit, it becomes difficult to correct various aberrations while making the variable-magnification optical system ZL compact. By setting the upper limit of conditional expression (9) to 4.50, 4.00, 3.75, 3.50, 3.25, 3.00, 2.75, 2.50, or even 2.30, the effects of each embodiment can be more reliably achieved. Furthermore, by setting the lower limit of conditional expression (9) to 0.20, 0.25, 0.30, 0.33, 0.35, 0.38, 0.40, 0.43, 0.45, or even 0.48, the effects of each embodiment can be more reliably achieved.

[0044] In the variable magnification optical systems ZL according to the first and second embodiments, it is desirable that at least one lens group in the rear group GR is made up of multiple lens groups, which allows for good correction of field curvature.

[0045] In the variable magnification optical systems ZL according to the first and second embodiments, it is desirable that at least one lens group in the rear group GR includes a second lens group G2 having positive refractive power that is positioned closest to the object side of the rear group GR, thereby enabling excellent correction of spherical aberration and coma.

[0046] In the variable magnification optical systems ZL according to the first and second embodiments, it is desirable that at least one lens group in the rear group GR includes a final lens group GE having positive refractive power and located closest to the image side of the rear group GR, thereby enabling good correction of field curvature.

[0047] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (10). 0.10 <fRPF / fRPR<0.60 ···(10) However, fRPF: the focal length of the lens group closest to the object that has positive refractive power among at least one lens group in the rear group GR. fRPR: the focal length of the lens group closest to the image among at least one lens group in the rear group GR that has positive refractive power

[0048] Conditional expression (10) defines an appropriate relationship between the focal length of the lens group having positive refractive power and closest to the object among the at least one lens group in the rear group GR, and the focal length of the lens group having positive refractive power and closest to the image among the at least one lens group in the rear group GR. By satisfying conditional expression (10), it is possible to achieve good correction of curvature of field, spherical aberration, coma, and other aberrations while maintaining a compact size.

[0049] If the value corresponding to conditional expression (10) exceeds the upper limit, the focal length of the lens group having positive refractive power in the rear group GR that is closest to the image becomes short, making it difficult to correct field curvature. By setting the upper limit of conditional expression (10) to 0.55, 0.50, 0.48, 0.45, 0.43, or even 0.40, the effects of each embodiment can be more reliably achieved.

[0050] If the value corresponding to conditional expression (10) falls below the lower limit, the focal length of the lens group having positive refractive power in the rear group GR that is closest to the object becomes short, making it difficult to correct spherical aberration and coma. By setting the lower limit of conditional expression (10) to 0.13, 0.15, 0.18, or even 0.20, the effects of each embodiment can be more reliably achieved.

[0051] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (11). 0.05 <Bfw / fRPR<0.35 ···(11) Bfw: back focus of the variable magnification optical system ZL in the wide-angle end state fRPR: the focal length of the lens group closest to the image among at least one lens group in the rear group GR that has positive refractive power

[0052] Conditional expression (11) defines an appropriate relationship between the back focal length of the variable magnification optical system ZL in the wide-angle end state and the focal length of the lens group having positive refractive power and located closest to the image side among at least one lens group in the rear group GR. By satisfying conditional expression (11), it is possible to effectively correct various aberrations such as curvature of field while maintaining a compact size. Note that in each embodiment, the back focal length of the variable magnification optical system ZL is the distance on the optical axis (air-equivalent distance) from the lens surface of the variable magnification optical system ZL located closest to the image side to the image plane I when focused at infinity.

[0053] If the value corresponding to conditional expression (11) exceeds the upper limit, the focal length of the lens group having positive refractive power in the rear group GR that is closest to the image becomes short, making it difficult to correct field curvature. By setting the upper limit of conditional expression (11) to 0.33, 0.30, 0.28, 0.25, or even 0.23, the effects of each embodiment can be more reliably achieved.

[0054] If the value corresponding to conditional expression (11) falls below the lower limit, the focal length of the lens group having positive refractive power in the rear group GR that is closest to the image becomes too long, making it difficult to sufficiently correct field curvature. By setting the lower limit of conditional expression (11) to 0.06, or even 0.08, the effects of each embodiment can be made more certain.

[0055] In the variable magnification optical systems ZL according to the first and second embodiments, it is desirable that the lens in the rear group GR located closest to the object side be a positive lens, which allows for good correction of field curvature.

[0056] The variable magnification optical systems ZL according to the first and second embodiments preferably have a stop disposed between the first lens group G1 and the rear lens group GR, which allows for good correction of coma.

[0057] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (12). 60.00°<2ωw<90.00° ···(12) However, 2ωw: the total angle of view of the variable magnification optical system ZL in the wide-angle end state

[0058] Conditional expression (12) defines an appropriate range for the total angle of view of the variable magnification optical system ZL in the wide-angle end state. Satisfying conditional expression (12) is preferable because it makes it possible to obtain a variable magnification optical system that is compact yet has good optical performance. By setting the upper limit of conditional expression (12) to 85.00°, 83.00°, 80.00°, or even 78.00°, the effects of each embodiment can be more reliably achieved. By setting the lower limit of conditional expression (12) to 63.00°, 65.00°, 68.00°, or even 70.00°, the effects of each embodiment can be more reliably achieved.

[0059] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (13). 1.50<(-f1) / fRw<3.00 (13) where f1 is the focal length of the first lens group G1 fRw: focal length of rear group GR at wide-angle end

[0060] Conditional expression (13) defines the appropriate relationship between the focal length of the first lens group G1 and the focal length of the rear group GR at the wide-angle end. By satisfying conditional expression (13), it is possible to obtain good optical performance over the entire zoom range, despite the compact size.

[0061] If the corresponding value of conditional expression (13) exceeds the upper limit, it becomes difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (13) to 2.95, 2.90, 2.85, 2.80, 2.75, or even 2.70, the effects of each embodiment can be further ensured.

[0062] If the corresponding value of conditional expression (13) falls below the lower limit, it becomes difficult to correct spherical aberration and curvature of field. By setting the lower limit of conditional expression (13) to 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.90, or even 2.00, the effects of each embodiment can be more reliably achieved.

[0063] It is desirable that the variable magnification optical system ZL according to the first and second embodiments satisfy the following conditional expression (14). 0.50<(-f1) / fRt<2.50 (14) where f1 is the focal length of the first lens group G1 fRt: focal length of rear group GR at telephoto end

[0064] Conditional expression (14) defines the appropriate relationship between the focal length of the first lens group G1 and the focal length of the rear group GR at the telephoto end. By satisfying conditional expression (14), it is possible to obtain good optical performance over the entire zoom range, despite the compact size.

[0065] If the corresponding value of conditional expression (14) exceeds the upper limit, it becomes difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (14) to 2.40, 2.30, 2.20, 2.10, 2.05, or even 2.00, the effects of each embodiment can be further ensured.

[0066] If the corresponding value of conditional expression (14) falls below the lower limit, it becomes difficult to correct spherical aberration and curvature of field. By setting the lower limit of conditional expression (14) to 0.55, 0.65, 0.75, 0.85, or even 0.90, the effects of each embodiment can be more reliably achieved.

[0067] Next, referring to FIG. 12, a manufacturing method for the variable magnification optical system ZL according to the first embodiment will be outlined. First, a first lens group G1 having negative refractive power and a rear group GR having at least one lens group are arranged, in order from the object side along the optical axis (Step ST1). Next, a configuration is established in which the spacing between adjacent lens groups changes during magnification (Step ST2). Next, at least a portion of at least one lens group in the rear group GR is configured as a focusing group GF having positive refractive power that moves along the optical axis during focusing (Step ST3). Then, the lenses are arranged within the lens barrel so as to satisfy at least the above-mentioned conditional expression (1) (Step ST4). This manufacturing method makes it possible to manufacture a variable magnification optical system that is compact yet has good optical performance.

[0068] Next, a manufacturing method for the variable magnification optical system ZL according to the second embodiment will be outlined. The manufacturing method for the variable magnification optical system ZL according to the second embodiment is similar to that described in the first embodiment, and will be described with reference to FIG. 12, as in the first embodiment. First, a first lens group G1 having negative refractive power and a rear group GR having at least one lens group are arranged, in order from the object side along the optical axis (Step ST1). Next, a configuration is established in which the spacing between adjacent lens groups changes during magnification (Step ST2). Next, at least a portion of at least one lens group in the rear group GR is configured as a focusing group GF having positive refractive power that moves along the optical axis during focusing (Step ST3). Finally, the lenses are arranged within the lens barrel so as to satisfy at least conditional expression (2) above (Step ST4). This manufacturing method makes it possible to manufacture a variable magnification optical system that is compact yet has excellent optical performance. [Example]

[0069] The variable magnification optical systems ZL according to examples of each embodiment will be described below with reference to the drawings. FIGS. 1, 3, 5, 7, and 9 are cross-sectional views showing the configuration and refractive power distribution of variable magnification optical systems ZL {ZL(1) to ZL(5)} according to Examples 1 to 5. In the cross-sectional views of the variable magnification optical systems ZL(1) to ZL(5) according to Examples 1 to 5, the direction of movement of the focusing group along the optical axis when focusing from infinity to a close-distance object is indicated by an arrow along with the word "focusing." In the cross-sectional views of the variable magnification optical systems ZL(1) to ZL(5) according to Examples 1 to 5, the direction of movement of each lens group along the optical axis when changing magnification from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow.

[0070] 1, 3, 5, 7, and 9, 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 numerous and complicated, each example uses its own unique combination of symbols and numbers to represent the lens groups, etc. Therefore, even if the same combination of symbols and numbers is used between examples, this does not mean that the examples have the same configuration.

[0071] Tables 1 to 5 are shown below, with Table 1 showing data on the various elements in Example 1, Table 2 in Example 2, Table 3 in Example 3, Table 4 in Example 4, and Table 5 in Example 5. In each example, the d-line (wavelength λ=587.6 nm) and g-line (wavelength λ=435.8 nm) were selected as the targets for calculating aberration characteristics.

[0072] In the [Overall Specifications] table, f is the focal length of the entire lens system, FNO is the F-number, ω is the half angle of view (unit: °), and Y is the image height. TL is the distance on the optical axis from the lens surface closest to the object in the variable magnification optical system to the lens surface closest to the image when focused at infinity, plus Bf (back focus), and Bf is the distance on the optical axis from the lens surface closest to the image in the variable magnification optical system to the image plane when focused at infinity (air equivalent distance). Note that these values ​​are shown for both the wide-angle end (W) and the telephoto end (T) of the variable magnification state.

[0073] In the table of overall specifications, fF indicates the focal length of the focusing group. fRw indicates the focal length of the rear group in the maximum wide-angle state. fRt indicates the focal length of the rear group in the maximum telephoto state. fFRw indicates the focal length of the lens group (image-side lens group) composed of lenses located closer to the image than the focusing group in the maximum wide-angle state. fFRt indicates the focal length of the lens group (image-side lens group) composed of lenses located closer to the image than the focusing group in the maximum telephoto state. fRPF indicates the focal length of the lens group with positive refractive power that is closest to the object among at least one lens group in the rear group. fRPR indicates the focal length of the lens group with positive refractive power that is closest to the image among at least one lens group in the rear group. βRw indicates the lateral magnification of the rear group in the maximum wide-angle state. βRt indicates the lateral magnification of the rear group in the maximum telephoto state.

[0074] In the [Lens Specifications] table, the surface number indicates the order of the optical surface from the object side along the direction of light ray travel, R is the radius of curvature of each optical surface (surfaces whose center of curvature is on the image side have 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 plane), nd is the refractive index of the optical element material with respect to the d-line, and νd is the Abbe number of the optical element material with respect to the d-line. The "∞" next to the radius of curvature indicates a flat surface or an aperture, and (stop S) indicates the aperture stop S. The refractive index of air, nd = 1.00000, is omitted. If the optical surface is aspherical, an * is added to the surface number, and the paraxial radius of curvature is shown in the "radius of curvature R" column.

[0075] 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 (amount of sag) along the optical axis from the tangent plane at the vertex 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 square root of the square root of the aspherical surface. -n For example, 1.234E-05 = 1.234 x 10 -5 The second-order aspherical coefficient A2 is 0, and is therefore omitted.

[0076] 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)

[0077] 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.

[0078] The [Lens Group Data] table shows the starting surface (the surface closest to the object) and focal length of each lens group.

[0079] In the following, for all specifications, the focal length f, radius of curvature R, surface spacing D, and other lengths are generally expressed in "mm" unless otherwise specified, but this is not limited to this, as the same optical performance can be obtained even when the optical system is proportionally enlarged or reduced.

[0080] The explanation of the tables up to this point is common to all the embodiments, and duplicate explanations will be omitted below.

[0081] (First Example) The first example will be described with reference to FIGS. 1 and 2 and Table 1. FIG. 1 shows the lens configuration of a variable magnification optical system according to the first example. The variable magnification optical system ZL(1) according to the first example is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having negative refractive power, an aperture stop S, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. When varying magnification from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move toward the object side along the optical axis, changing the spacing between adjacent lens groups. Furthermore, during magnification variation, the aperture stop S moves along the optical axis together with the second lens group G2, while the position of the fifth lens group G5 is fixed relative to the image plane I. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of that lens group, and this is the same in all of the following examples.

[0082] The first lens group G1 is composed of, arranged along the optical axis from the object side, a biconcave negative lens L11 and a positive meniscus lens L12 with its convex surface facing the object side. Both lens surfaces of the negative lens L11 are aspherical.

[0083] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a positive meniscus lens L21 with its convex surface facing the object side, a biconvex positive lens L22, and a negative meniscus lens L23 with its convex surface facing the object side. Both lens surfaces of the positive meniscus lens L21 are aspherical.

[0084] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L31 with its concave surface facing the object side, and a biconvex positive lens L32. The positive lens L32 has an aspherical lens surface facing the image side.

[0085] The fourth lens group G4 is composed of a negative meniscus lens L41 with a concave surface facing the object side, and the lens surface facing the object side of the negative meniscus lens L41 is aspherical.

[0086] The fifth lens group G5 is composed of a positive meniscus lens L51 with its concave surface facing the object side. The positive meniscus lens L51 has an aspherical lens surface facing the image side. An image surface I is located on the image side of the fifth lens group G5.

[0087] In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GR, which has a positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE, which is located closest to the image side of the rear group GR. The entire third lens group G3 constitutes the focusing group GF, which moves along the optical axis during focusing. When focusing from an object at infinity to an object at close range, the focusing group GF (the entire third lens group G3) moves toward the object along the optical axis. The fourth lens group G4 (negative meniscus lens L41) and the fifth lens group G5 (positive meniscus lens L51) constitute an image-side lens group GFR, which is composed of lenses located closer to the image side than the focusing group GF.

[0088] Table 1 below lists the values ​​of the specifications of the variable magnification optical system according to the first example.

[0089] (Table 1) [Overall specifications] Magnification ratio=1.636 fF=39.167 fRw=22.595 fRt=29.061 fFRw=-41.499 fFRt=-59.874 fRPF=20.954 fRPR=70.338 βRw=-0.617 βRt=-1.010 WMT f 29.700 38.460 48.600 FNO 4.760 5.730 6.600 ω 36.800 30.000 23.900 Y 20.260 21.600 21.600 TL 53.000 54.360 55.000 Bf 9.350 9.350 9.350 [Lens specifications] Surface number RD nd νd 1* -46.45344 0.70000 1.592450 66.92 2* 32.53983 0.27192 3 31.89076 1.16857 1.922860 20.88 4 49.15523 (D4) 5 ∞ 0.75000 (Aperture S) 6* 9.25078 1.69319 1.592550 67.86 7* 22.86502 0.52358 8* 21.08977 2.02472 1.497103 81.56 9 -33.77515 0.10000 10 14.66767 0.60000 1.805180 25.45 11 8.87343 (D11) 12 -10.72084 0.60000 1.647690 33.72 13 -88.96305 0.10000 14 153.50950 4.46285 1.806040 40.74 15* -12.62204 (D15) 16* -12.55590 1.10000 1.592550 67.86 17 -124.66776 (D17) 18 -76.00140 4.00911 1.806040 40.74 19* -33.23634 Bf [Aspherical data] Front page κ=1.0000,A4=-2.87832E-05,A6=5.37667E-07,A8=-1.89799E-09,A10=0.00000E+00 2nd side κ=1.0000,A4=-3.52496E-05,A6=4.89315E-07,A8=0.00000E+00,A10=0.00000E+00 Page 6 κ=1.0000,A4=4.25254E-04,A6=6.57900E-06,A8=0.00000E+00,A10=0.00000E+00 Page 7 κ=1.0000,A4=1.56672E-03,A6=-2.37553E-06,A8=0.00000E+00,A10=0.00000E+00 Page 8 κ=1.0000,A4=1.07233E-03,A6=-1.74719E-05,A8=0.00000E+00,A10=0.00000E+00 Page 15 κ=1.0000,A4=5.95097E-05,A6=2.02778E-07,A8=0.00000E+00,A10=0.00000E+00 Page 16 κ=1.0000,A4=6.61988E-05,A6=3.19123E-08,A8=0.00000E+00,A10=0.00000E+00 Page 19 κ=1.0000,A4=1.04032E-05,A6=-1.75552E-08,A8=0.00000E+00,A10=0.00000E+00 [Can change the interval データ] Infinity focus state WMT Focus distance 29.700 38.460 48.600 Object distance ∞ ∞ ∞ D4 9.80415 5.69022 0.77539 D11 7.02876 8.50376 7.42174 D15 6.66505 4.79534 5.00000 D17 2.04808 7.91189 14.34901 Close focus WMT Magnification -0.09457 -0.12295 -0.15908 Object distance 300.0000 300.0000 300.0000 D4 9.80415 5.69022 0.77539 D11 4.41909 5.26604 3.84392 D15 9.27473 8.03306 8.57782 D17 2.04808 7.91189 14.34901 [Lens group data] Group starting plane focal length G1 1 -48.133 G2 6 20.954 G3 12 39.167 G4 16 -23.649 G5 18 70.338

[0090] FIG. 2(A) shows various aberration diagrams of the variable magnification optical system of Example 1 when focused at infinity in the wide-angle end state. FIG. 2(B) shows various aberration diagrams of the variable magnification optical system of Example 1 when focused at infinity in the telephoto end state. In each aberration diagram, FNO indicates the F-number, and Y indicates the image height. Note that the spherical aberration diagram indicates the F-number value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram indicate the maximum image height, and the coma diagram indicates the value of each image height. d indicates the d-line (wavelength λ=587.6 nm), and g indicates the g-line (wavelength λ=435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the dashed line indicates the meridional image plane. Note that the same symbols as in this example are used in the aberration diagrams of each example shown below, and redundant explanations will be omitted.

[0091] From the various aberration diagrams, it can be seen that the variable magnification optical system according to Example 1 has excellent correction of various aberrations from the wide-angle end state to the telephoto end state, and has excellent imaging performance.

[0092] (Second Example) The second example will be described with reference to FIGS. 3 and 4 and Table 2. FIG. 3 shows the lens configuration of a variable magnification optical system according to the second example. The variable magnification optical system ZL(2) according to the second example is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having negative refractive power, an aperture stop S, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. When varying magnification from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move toward the object side along the optical axis, changing the spacing between adjacent lens groups. Furthermore, when the magnification is changed, the aperture stop S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 relative to the image plane I is fixed.

[0093] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a biconcave negative lens L11 and a biconvex positive lens L12. Both lens surfaces of the negative lens L11 are aspherical.

[0094] The second lens group G2 is composed of, arranged along the optical axis from the object side, a biconvex positive lens L21 and a negative meniscus lens L22 with its convex surface facing the object side. Both lens surfaces of the positive lens L21 are aspherical.

[0095] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L31 with its concave surface facing the object side, and a biconvex positive lens L32. The positive lens L32 has an aspherical lens surface facing the image side.

[0096] The fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L41 with a convex surface facing the object side and a negative meniscus lens L42 with a concave surface facing the object side. The negative meniscus lens L42 has an aspherical lens surface facing the image side.

[0097] The fifth lens group G5 is composed of a positive meniscus lens L51 with its concave surface facing the object side. The positive meniscus lens L51 has an aspherical lens surface facing the image side. An image surface I is located on the image side of the fifth lens group G5.

[0098] In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GR, which has a positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE, which is located closest to the image side of the rear group GR. The entire third lens group G3 constitutes the focusing group GF, which moves along the optical axis during focusing. When focusing from an object at infinity to a close object, the focusing group GF (the entire third lens group G3) moves toward the object along the optical axis. The fourth lens group G4 (negative meniscus lens L41 and negative meniscus lens L42) and the fifth lens group G5 (positive meniscus lens L51) constitute an image-side lens group GFR, which is composed of lenses located closer to the image side than the focusing group GF.

[0099] Table 2 below lists the values ​​of the specifications of the variable magnification optical system according to the second example.

[0100] (Table 2) [Overall specifications] Magnification ratio=1.636 fF=26.338 fRw=26.032 fRt=58.204 fFRw=-29.697 fFRt=-53.723 fRPF=21.696 fRPR=55.306 βRw=-0.449 βRt=-0.601 WMT f 29.700 38.000 48.600 FNO 4.760 5.730 6.600 ω 36.600 29.600 23.700 Y 20.800 21.600 21.600 TL 49.450 41.640 54.950 Bf 9.400 9.410 9.400 [Lens specifications] Surface number RD nd νd 1* -30.00033 0.70000 1.677980 54.89 2* 27.02686 0.30000 3 44.93551 1.30000 2.001000 29.12 4 -169.34876 (D4) 5 ∞ 0.75000 (Aperture S) 6* 8.93744 2.40000 1.497103 81.56 7* -41.28092 0.10000 8 9.85432 0.85000 1.846660 23.80 9 7.22445 (D9) 10 -9.42267 0.60000 1.592700 35.27 11 -36.11138 0.53556 12 44.47304 3.77778 1.658440 50.83 13* -10.73978 (D13) 14 83.46657 0.60000 1.677980 54.89 15 19.47713 7.71820 16 -9.23773 1.10000 1.592550 67.86 17* -18.61767 (D17) 18 -48.35114 4.85915 1.820980 42.50 19* -24.47680 Bf [Aspherical data] Front page κ=1.0000,A4=7.08353E-07,A6=-7.32782E-08,A8=1.68078E-10,A10=0.00000E+00 2nd side κ=1.0000,A4=-2.56974E-05,A6=-1.03240E-07,A8=0.00000E+00,A10=0.00000E+00 Side 6 κ=1.0000,A4=-1.17527E-04,A6=-1.07846E-06,A8=0.00000E+00,A10=0.00000E+00 Page 7 κ=1.0000,A4=4.05573E-05,A6=-1.34572E-08,A8=0.00000E+00,A10=0.00000E+00 Page 13 κ=1.0000,A4=1.20435E-04,A6=5.06907E-07,A8=0.00000E+00,A10=0.00000E+00 Page 17 κ=1.0000,A4=-4.34454E-05,A6=-1.59225E-07,A8=0.00000E+00,A10=0.00000E+00 Page 19 κ=1.0000,A4=3.48547E-06,A6=1.98136E-08,A8=0.00000E+00,A10=0.00000E+00 [Can change the interval データ] Infinity focus state WMT Focus distance 29.700 38.000 48.600 Object distance ∞ ∞ ∞ D4 7.79982 3.90180 0.75000 D9 3.42610 3.93525 4.42251 D13 2.53363 1.66766 0.90000 D17 0.70000 6.54202 13.88678 Close focus WMT Magnification -0.09863 -0.12512 -0.16148 Object distance 300.0000 300.0000 300.0000 D4 7.79982 3.90180 0.75000 D9 2.26584 2.56819 2.84604 D13 3.69388 3.03472 2.47647 D17 0.70000 6.54202 13.88678 [Lens group data] Group starting plane focal length G1 1 -52.725 G2 6 21.696 G3 10 26.338 G4 14 -15.833 G5 18 55.306

[0101] Fig. 4(A) is a diagram showing various aberrations when the variable magnification optical system according to Example 2 is focused at infinity in the wide-angle end state. Fig. 4(B) is a diagram showing various aberrations when the variable magnification optical system according to Example 2 is focused at infinity in the telephoto end state. From these aberration diagrams, it can be seen that the variable magnification optical system according to Example 2 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the telephoto end state.

[0102] (Third Example) Example 3 will be described with reference to FIGS. 5 and 6 and Table 3. FIG. 5 shows the lens configuration of a variable magnification optical system according to Example 3. The variable magnification optical system ZL(3) according to Example 3 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having negative refractive power, an aperture stop S, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. When varying magnification from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move toward the object side along the optical axis, changing the spacing between adjacent lens groups. Furthermore, when the magnification is changed, the aperture stop S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 relative to the image plane I is fixed.

[0103] The first lens group G1 is composed of, arranged along the optical axis from the object side, a biconcave negative lens L11 and a positive meniscus lens L12 with its convex surface facing the object side. Both lens surfaces of the negative lens L11 are aspherical.

[0104] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a positive meniscus lens L21 with its convex surface facing the object side, a positive meniscus lens L22 with its convex surface facing the object side, and a negative meniscus lens L23 with its convex surface facing the object side. Both lens surfaces of the positive meniscus lens L21 are aspherical.

[0105] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L31 with its concave surface facing the object side, and a biconvex positive lens L32. The positive lens L32 has an aspherical lens surface facing the image side.

[0106] The fourth lens group G4 is composed of a negative meniscus lens L41 with a concave surface facing the object side, and the lens surface facing the image side of the negative meniscus lens L41 is aspherical.

[0107] The fifth lens group G5 is composed of a positive meniscus lens L51 with its concave surface facing the object side. The positive meniscus lens L51 has an aspherical lens surface facing the image side. An image surface I is located on the image side of the fifth lens group G5.

[0108] In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GR, which has a positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE, which is located closest to the image side of the rear group GR. The entire third lens group G3 constitutes the focusing group GF, which moves along the optical axis during focusing. When focusing from an object at infinity to an object at close range, the focusing group GF (the entire third lens group G3) moves toward the object along the optical axis. The fourth lens group G4 (negative meniscus lens L41) and the fifth lens group G5 (positive meniscus lens L51) constitute an image-side lens group GFR, which is composed of lenses located closer to the image side than the focusing group GF.

[0109] Table 3 below lists the values ​​of the specifications of the variable magnification optical system according to the third example.

[0110] (Table 3) [Overall specifications] Magnification ratio=1.636 fF=42.997 fRw=28.117 fRt=47.910 fFRw=-53.580 fFRt=-76.170 fRPF=23.675 fRPR=80.136 βRw=-0.471 βRt=-0.612 WMT f 29.700 38.000 48.600 FNO 4.620 5.500 6.630 ω 36.950 30.400 23.770 Y 20.030 21.600 21.600 TL 53.000 53.500 56.560 Bf 9.350 9.350 9.350 [Lens specifications] Surface number RD nd νd 1* -31.73727 0.70000 1.497103 81.56 2* 29.09010 0.44719 3 43.66364 1.20961 2.000690 25.46 4 122.92529 (D4) 5 ∞ 0.75000 (Aperture S) 6* 12.35536 1.63881 1.497103 81.56 7* 57.04352 0.10000 8 12.73259 1.70614 1.496997 81.61 9 197.72930 0.10000 10 13.90270 0.60000 1.784720 25.64 11 8.83064 (D11) 12 -12.80974 0.55000 1.749500 35.25 13 -617.21941 0.10000 14 71.30483 5.01710 1.820980 42.50 15* -13.72803 (D15) 16 -13.40787 1.10000 1.563840 60.71 17* -68.71419 (D17) 18 -45.00000 3.23796 1.902650 35.77 19* -28.68872 Bf [Aspherical surface] Page 1 κ=1.0000,A4=6.95146E-06,A6=7.90721E-08,A8=-4.86954E-10,A10=0.00000E+00 Page 2 κ=1.0000,A4=-1.21033E-05,A6=4.19563E-08,A8=0.00000E+00,A10=0.00000E+00 Page 6 κ=1.0000,A4=-3.26113E-05,A6=5.99810E-07,A8=0.00000E+00,A10=0.00000E+00 Page 7 κ=1.0000,A4=4.51406E-05,A6=7.80522E-07,A8=0.00000E+00,A10=0.00000E+00 Page 15 κ=1.0000,A4=5.20915E-05,A6=1.39991E-07,A8=0.00000E+00,A10=0.00000E+00 Page 17 κ=1.0000,A4=-3.68987E-05,A6=7.05431E-08,A8=0.00000E+00,A10=0.00000E+00 Page 19 κ=1.0000,A4=2.55064E-06,A6=1.13229E-08,A8=0.00000E+00,A10=0.00000E+00 [Can change the interval データ] Infinity focus state WMT Focal length 29.700 38.000 48.600 Object distance ∞ ∞ ∞ D4 8.70643 4.12083 0.50000 D11 6.88074 8.48181 10.47382 D15 10.10609 7.59408 5.07986 D17 0.70000 6.69783 13.89998 Close focus state WMT Magnification -0.09550 -0.12308 -0.15793 Object distance 300.0000 300.0000 300.0000 D4 8.70643 4.12083 0.50000 D11 3.91794 4.80666 5.95890 D15 13.06889 11.26923 9.59478 D17 0.70000 6.69783 13.89998 [Lens group data] Group starting plane focal length G1 1 -56.116 G2 6 23.675 G3 12 42.997 G4 16 -29.758 G5 18 80.136

[0111] Fig. 6(A) is a diagram showing various aberrations when the variable magnification optical system according to Example 3 is focused at infinity in the wide-angle end state. Fig. 6(B) is a diagram showing various aberrations when the variable magnification optical system according to Example 3 is focused at infinity in the telephoto end state. From these aberration diagrams, 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.

[0112] (Fourth Example) Example 4 will be described with reference to FIGS. 7 and 8 and Table 4. FIG. 7 shows the lens configuration of a variable magnification optical system according to Example 4. The variable magnification optical system ZL(4) according to Example 4 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having negative refractive power, an aperture stop S, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. When varying magnification from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move toward the object side along the optical axis, changing the spacing between adjacent lens groups. Furthermore, when the magnification is changed, the aperture stop S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 relative to the image plane I is fixed.

[0113] The first lens group G1 is composed of, arranged along the optical axis from the object side, a biconcave negative lens L11 and a positive meniscus lens L12 with its convex surface facing the object side. Both lens surfaces of the negative lens L11 are aspherical.

[0114] The second lens group G2 is composed of, arranged in order from the object side along the optical axis, a positive meniscus lens L21 with a convex surface facing the object side, a biconvex positive lens L22, and a negative meniscus lens L23 with a convex surface facing the object side. The positive meniscus lens L21 has aspherical lens surfaces on both sides. The positive lens L22 has an aspherical lens surface facing the object side.

[0115] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L31 with its concave surface facing the object side and a positive meniscus lens L32 with its concave surface facing the object side. The positive meniscus lens L32 has an aspherical lens surface facing the image side.

[0116] The fourth lens group G4 is composed of a negative meniscus lens L41 with a concave surface facing the object side, and the lens surface facing the object side of the negative meniscus lens L41 is aspherical.

[0117] The fifth lens group G5 is composed of a positive meniscus lens L51 with its concave surface facing the object side. The positive meniscus lens L51 has an aspherical lens surface facing the image side. An image surface I is located on the image side of the fifth lens group G5.

[0118] In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GR, which has a positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE, which is located closest to the image side of the rear group GR. The entire third lens group G3 constitutes the focusing group GF, which moves along the optical axis during focusing. When focusing from an object at infinity to an object at close range, the focusing group GF (the entire third lens group G3) moves toward the object along the optical axis. The fourth lens group G4 (negative meniscus lens L41) and the fifth lens group G5 (positive meniscus lens L51) constitute an image-side lens group GFR, which is composed of lenses located closer to the image side than the focusing group GF.

[0119] Table 4 below lists the values ​​of the specifications of the variable magnification optical system according to the fourth example.

[0120] (Table 4) [Overall specifications] Magnification ratio=1.636 fF=39.607 fRw=14.368 fRt=19.725 fFRw=-38.346 fFRt=-47.636 fRPF=19.063 fRPR=92.773 βRw=-0.520 βRt=-0.827 WMT f 29.700 38.100 48.600 FNO 4.860 5.710 6.670 ω 36.990 30.866 24.530 Y 19.910 21.600 21.600 TL 53.000 53.500 56.560 Bf 9.350 9.350 9.350 [Lens specifications] Surface number R D nd νd 1* -30.22701 0.70000 1.592450 66.92 2* 36.12436 0.25453 3 30.95344 1.15584 1.922860 20.88 4 46.70993 (D4) 5 ∞ 0.75000 (Aperture S) 6* 9.39854 2.20000 1.592550 67.86 7* 27.34671 0.51079 8* 25.75786 2.17114 1.497103 81.56 9 -22.85474 0.10000 10 18.36723 0.60000 1.805180 25.45 11 10.11386 (D11) 12 -10.75318 0.55000 1.647690 33.72 13 -29.87660 0.90072 14 -112.83117 3.80151 1.806040 40.74 15* -13.08031 (D15) 16* -13.03175 1.10000 1.592550 67.86 17 -123.29153 (D17) 18 -47.94418 3.31541 1.806040 40.74 19* -30.11543 Bf [Aspherical data] First surface κ = 1.0000, A4 = 2.22481E-05, A6 = 1.01445E-07, A8 = -4.79173E-10, A10 = 0.00000E+00 Second surface κ = 1.0000, A4 = 1.60025E-05, A6 = 1.58116E-07, A8 = 0.00000E+00, A10 = 0.00000E+00 Sixth surface κ=1.0000,A4=3.49725E-04,A6=3.83667E-06,A8=0.00000E+00,A10=0.00000E+00 Page 7 κ=1.0000,A4=1.47564E-03,A6=-3.55272E-06,A8=0.00000E+00,A10=0.00000E+00 Page 8 κ=1.0000,A4=9.92751E-04,A6=-1.52345E-05,A8=0.00000E+00,A10=0.00000E+00 Page 15 κ=1.0000,A4=4.70062E-05,A6=1.55390E-07,A8=0.00000E+00,A10=0.00000E+00 Page 16 κ=1.0000,A4=6.63363E-05,A6=4.07593E-08,A8=0.00000E+00,A10=0.00000E+00 Page 19 κ=1.0000,A4=1.37067E-05,A6=-3.22794E-08,A8=0.00000E+00,A10=0.00000E+00 [Can change the interval データ] Infinity focus state WMT Focus distance 29.700 38.100 48.600 Object distance ∞ ∞ ∞ D4 8.46288 4.50520 0.78230 D11 6.58757 6.69428 7.03152 D15 6.16194 5.33365 5.04300 D17 3.03775 8.84685 14.68335 Close focus WMT Magnification -0.09468 -0.12283 -0.15875 Object distance 300.0000 300.0000 300.0000 D4 8.46288 4.50520 0.78230 D11 3.98574 3.68930 3.48054 D15 8.76377 8.33863 8.59397 D17 3.03775 8.84685 14.68335 [Lens group data] Group starting plane focal length G1 1 -38.500 G2 6 19.063 G3 12 39.607 G4 16 -24.684 G5 18 92.773

[0121] Fig. 8(A) is a diagram showing various aberrations when the variable magnification optical system according to Example 4 is focused at infinity in the wide-angle end state. Fig. 8(B) is a diagram showing various aberrations when the variable magnification optical system according to Example 4 is focused at infinity in the telephoto end state. From these aberration diagrams, it can be seen that the variable magnification optical system according to Example 4 has excellent correction of various aberrations from the wide-angle end state to the telephoto end state, and has excellent imaging performance.

[0122] (Fifth Example) Fifth Example will be described with reference to FIGS. 9 and 10 and Table 5. FIG. 9 shows the lens configuration of a variable magnification optical system according to the fifth example. The variable magnification optical system ZL(5) according to the fifth example is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having negative refractive power, an aperture stop S, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. When varying magnification from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move toward the object side along the optical axis, changing the spacing between adjacent lens groups. Furthermore, when the magnification is changed, the aperture stop S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 relative to the image plane I is fixed.

[0123] The first lens group G1 is composed of, arranged along the optical axis from the object side, a biconcave negative lens L11 and a positive meniscus lens L12 with its convex surface facing the object side. Both lens surfaces of the negative lens L11 are aspherical.

[0124] The second lens group G2 is composed of, arranged along the optical axis from the object side, a biconvex positive lens L21 and a negative meniscus lens L22 with its convex surface facing the object side. Both lens surfaces of the positive lens L21 are aspherical.

[0125] The third lens group G3 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L31 with its concave surface facing the object side, and a biconvex positive lens L32. The positive lens L32 has an aspherical lens surface facing the image side.

[0126] The fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, a negative meniscus lens L41 with a convex surface facing the object side and a negative meniscus lens L42 with a concave surface facing the object side. The negative meniscus lens L42 has an aspherical lens surface facing the image side.

[0127] The fifth lens group G5 is composed of a positive meniscus lens L51 with its concave surface facing the object side. The positive meniscus lens L51 has an aspherical lens surface facing the image side. An image surface I is located on the image side of the fifth lens group G5.

[0128] In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GR, which has a positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE, which is located closest to the image side of the rear group GR. The entire third lens group G3 constitutes the focusing group GF, which moves along the optical axis during focusing. When focusing from an object at infinity to a close object, the focusing group GF (the entire third lens group G3) moves toward the object along the optical axis. The fourth lens group G4 (negative meniscus lens L41 and negative meniscus lens L42) and the fifth lens group G5 (positive meniscus lens L51) constitute an image-side lens group GFR, which is composed of lenses located closer to the image side than the focusing group GF.

[0129] Table 5 below lists the values ​​of the specifications of the variable magnification optical system according to the fifth example.

[0130] (Table 5) [Overall specifications] Magnification ratio=1.636 fF=31.496 fRw=18.762 fRt=37.924 fFRw=-36.619 fFRt=-56.429 fRPF=23.697 fRPR=68.376 βRw=-0.461 βRt=-0.831 WMT f 29.700 38.000 48.600 FNO 4.580 5.430 6.500 ω 37.080 30.530 24.080 Y 20.040 21.600 21.600 TL 54.950 55.910 59.420 Bf 9.400 9.400 9.400 [Lens specifications] Surface number RD nd νd 1* -42.08161 0.70000 1.592550 67.86 2* 19.04481 0.7948 3 24.04182 1.50000 1.850260 32.35 4 76.98855 (D4) 5 ∞ 0.75000 (Aperture S) 6* 10.14764 2.30492 1.497103 81.56 7* -41.88647 0.10000 8 10.76220 0.85000 1.846660 23.80 9 8.06657 (D9) 10 -9.84224 0.60000 1.647690 33.72 11 -30.44625 1.18506 12 302.30818 3.12363 1.773870 47.25 13* -12.17516 (D13) 14 69.03850 1.05590 1.667550 41.87 15 23.59872 10.14456 16 -13.80249 1.10000 1.603000 65.44 17* -33.16908 (D17) 18 -500.00000 4.50318 1.804400 39.61 19* -49.74990 Bf [Aspherical surface] Page 1 κ=1.0000,A4=-4.37082E-07,A6=1.20726E-08,A8=-7.58568E-11,A10=0.00000E+00 Page 2 κ=1.0000,A4=-1.47336E-05,A6=-1.76298E-08,A8=0.00000E+00,A10=0.00000E+00 Page 6 κ=1.0000,A4=-7.82571E-05,A6=-4.39086E-07,A8=0.00000E+00,A10=0.00000E+00 Page 7 κ=1.0000,A4=2.97493E-05,A6=-3.34092E-08,A8=0.00000E+00,A10=0.00000E+00 Page 13 κ=1.0000,A4=6.63179E-05,A6=2.88117E-07,A8=0.00000E+00,A10=0.00000E+00 Page 17 κ=1.0000,A4=-2.73274E-05,A6=1.19063E-08,A8=0.00000E+00,A10=0.00000E+00 Page 19 κ = 1.0000, A4 = 2.70508E - 06, A6 = -2.22490E - 09, A8 = 0.00000E + 00, A10 = 0.00000E + 00 [Variable interval data] Infinity focus state WMT Focal length 29.700 38.000 48.600 Object distance ∞ ∞ ∞ D4 9.13726 4.49172 0.75000 D9 4.33920 4.81383 5.20970 D13 2.65195 1.72334 0.90000 D17 0.70000 6.76704 14.44365 Closest focus state WMT Magnification -0.09640 -0.12487 -0.16166 Object distance 300.0000 300.0000 300.0000 D4 9.13726 4.49172 0.75000 D9 2.82451 3.00662 3.08197 D13 4.14864 3.53055 3.02772 D17 0.70000 6.76704 14.44365 [Lens group data] Group Starting surface Focal length G1 1 -49.718 G2 6 23.697 G3 10 31.496<着ID= G4 14 -20.966 G5 18 68.376

[0131] Fig. 10(A) is a diagram showing various aberrations when the variable magnification optical system according to Example 5 is focused at infinity in the wide-angle end state. Fig. 10(B) is a diagram showing various aberrations when the variable magnification optical system according to Example 5 is focused at infinity in the telephoto end state. From these aberration diagrams, 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.

[0132] Next, the table of [Values ​​Corresponding to Conditional Expressions] is shown below: This table shows the values ​​corresponding to each of the conditional expressions (1) to (14) for all the examples (Examples 1 to 5). Condition (1) 0.50 <ft / fF<10.00 Condition (2) 0.30 <fw / fF<7.00 Condition (3) 1.30 <f2 / (-X2)<2.50 Conditional expression (4) 1.00<βRt / βRw<2.25 Condition (5) 0.30<(-fFRw) / fF<7.00 Conditional expression (6) 0.30<(-fFRt) / fF<7.00 Condition (7) 0.20 <fRPF / fF<3.00 Condition (8) 0.15 <fRw / fF<4.00 Condition (9) 0.15 <fRt / fF<5.00 Condition (10) 0.10 <fRPF / fRPR<0.60 Condition (11) 0.05 <Bfw / fRPR<0.35 Conditional expression (12) 60.00°<2ωw<90.00° Conditional expression (13) 1.50<(-f1) / fRw<3.00 Conditional expression (14) 0.50<(-f1) / fRt<2.50

[0133] [Conditional Expression Corresponding Values] (First to Third Examples) Conditional Expression First Example Second Example Third Example (1) 1.241 1.845 1.130 (2) 0.758 1.128 0.691 (3) 1.900 1.729 2.012 (4) 1.636 1.338 1.300 (5) 1.060 1.128 1.246 (6) 1.529 2.040 1.772 (7) 0.535 0.824 0.551 (8) 0.577 0.988 0.654 (9) 0.742 2.210 1.114 (10) 0.298 0.392 0.295 (11) 0.133 0.170 0.117 (12) 73.635 73.209 73.904 (13) 2.130 2.025 1.996 (14) 1.656 0.906 1.171 [Conditional Expression Corresponding Values] (Fourth and Fifth Examples) Conditional Expressions Fourth Example Fifth Example (1) 1.227 1.543 (2) 0.750 0.943 (3) 1.738 1.842 (4) 1.592 1.802 (5) 0.968 1.163 (6) 1.203 1.792 (7) 0.481 0.752 (8) 0.363 0.596 (9) 0.498 1.204 (10) 0.205 0.347 (11) 0.101 0.138 (12) 73.971 74.162 (13) 2.680 2.650 (14) 1.952 1.311

[0134] According to each of the above embodiments, it is possible to realize a variable magnification optical system that is compact yet has good optical performance.

[0135] The above-described examples are merely illustrative examples of the present invention, and the present invention is not limited to these.

[0136] The following contents can be appropriately adopted within the scope that does not impair the optical performance of the variable magnification optical system of this embodiment.

[0137] Although a five-group configuration has been shown as an example of the variable magnification optical system of this embodiment, the present application is not limited to this, and variable magnification optical systems with other group configurations (for example, six groups, seven groups, etc.) can also be configured. Specifically, a lens or lens group may be added to the variable magnification optical system of this embodiment closest to the object or closest to the image plane. 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.

[0138] A single lens group, 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 a close object. The focusing lens group can also be used for autofocusing, and is suitable for driving a motor (using an ultrasonic motor, etc.) for autofocusing.

[0139] 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 (oscillated) in a plane including the optical axis, to serve as an image stabilization lens group that corrects image blur caused by camera shake.

[0140] The lens surface may be spherical, flat, or aspherical. Spherical or flat lens surfaces are preferred because they facilitate lens processing and assembly adjustment, and prevent degradation of optical performance due to errors in processing and assembly adjustment. Furthermore, they are preferred because they minimize degradation of imaging performance even when the image plane is misaligned.

[0141] If the lens surface is aspherical, the aspherical surface may be any of the following: a ground aspherical surface, a glass-molded aspherical surface in which glass is molded into an aspherical shape, or a hybrid aspherical surface in which a resin is formed into an aspherical 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.

[0142] The aperture diaphragm is preferably disposed between the first lens group and the second lens group, but it is also possible to use the lens frame to fulfill that role instead of providing a member serving as an aperture diaphragm.

[0143] Each lens surface may be coated with an anti-reflection coating that has high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high-contrast optical performance. [Explanation of symbols]

[0144] G1 First lens group G2 Second lens group G3 3rd lens group G4 4th lens group G5 5th lens group I Image plane S Aperture stop

Claims

1. the first lens group having negative refractive power and the rear lens group having at least one lens group, which are arranged in order from the object side along the optical axis, When changing magnification, the spacing between adjacent lens groups changes, at least a part of the lens group in the at least one lens group in the rear group is a focusing group having positive refractive power that moves along the optical axis during focusing, A variable magnification optical system that satisfies the following condition: 0.30<fw / fF<7.00 where fw is the focal length of the variable magnification optical system in the wide-angle end state fF: focal length of the focusing group

2. the at least one lens group in the rear group includes a second lens group having positive refractive power and arranged closest to the object side of the rear group, 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 1.30<f2 / (-X2)<2.50 where f2 is the focal length of the second lens group X2: the movement amount of the second lens group when changing magnification from the wide-angle end state to the telephoto end state (the movement amount toward the image side is a positive value)

3. 3. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 1.00<βRt / βRw<2.25 where βRt is the lateral magnification of the rear group in the telephoto end state. βRw: lateral magnification of the rear group in the wide-angle end state

4. 4. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.30<(-fFRw) / fF<7.00 where fFRw is the focal length of the lens group configured with lenses arranged closer to the image side than the focusing group in the wide-angle end state.

5. 5. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.30<(-fFRt) / fF<7.00 where fFRt is the focal length of the lens group configured with lenses arranged closer to the image side than the focusing group in the telephoto end state.

6. 6. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.20<fRPF / fF<3.00 where fRPF is the focal length of the lens group having positive refractive power and closest to the object side among the at least one lens group in the rear group.

7. 7. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.15<fRw / fF<4.00 where fRw is the focal length of the rear group in the wide-angle end state

8. 8. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.15<fRt / fF<5.00 where fRt is the focal length of the rear group in the telephoto end state

9. 9. A variable magnification optical system according to claim 1, wherein the at least one lens group in the rear group is a plurality of lens groups.

10. 10. The variable magnification optical system according to claim 1, wherein the at least one lens group in the rear group includes a second lens group having positive refractive power that is arranged closest to the object side of the rear group.

11. 11. The variable magnification optical system according to claim 1, wherein the at least one lens group in the rear group includes a final lens group having positive refractive power and arranged closest to the image side of the rear group.

12. 12. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.10<fRPF / fRPR<0.60 where fRPF is the focal length of the lens group having positive refractive power and closest to the object side among the at least one lens group in the rear group. fRPR: the focal length of the lens group having positive refractive power and closest to the image side among the at least one lens group in the rear group

13. 13. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.05<Bfw / fRPR<0.35 where Bfw is the back focus of the variable magnification optical system in the wide-angle end state. fRPR: the focal length of the lens group having positive refractive power and closest to the image side among the at least one lens group in the rear group

14. 14. The variable magnification optical system according to claim 1, wherein the lens in the rear group arranged closest to the object side is a positive lens.

15. 15. The variable magnification optical system according to claim 1, further comprising a stop disposed between the first lens group and the rear lens group.

16. 16. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 60.00°<2ωw<90.00° where 2ωw is the total angle of view of the variable magnification optical system in the wide-angle end state.

17. 17. The variable magnification optical system according to claim 1, which satisfies the following condition: 1.50<(-f1) / fRw<3.00 where f1 is the focal length of the first lens group fRw: focal length of the rear lens group at the wide-angle end

18. 18. A variable magnification optical system according to claim 1, which satisfies the following condition: 0.50<(-f1) / fRt<2.50 where f1 is the focal length of the first lens group fRt: focal length of the rear group in the telephoto end state

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

20. A method for manufacturing a variable magnification optical system including a first lens group having negative refractive power and a rear lens group having at least one lens group, which are arranged in order from the object side along an optical axis, the method comprising: When changing magnification, the spacing between adjacent lens groups changes, at least a part of the lens group in the at least one lens group in the rear group is a focusing group having positive refractive power that moves along the optical axis during focusing, To satisfy the following condition, A manufacturing method for a variable magnification optical system in which each lens is arranged inside a lens barrel. 0.30<fw / fF<7.00 where fw is the focal length of the variable magnification optical system in the wide-angle end state fF: focal length of the focusing group

Images