Variable power optical system and optical device

Abstract

To provide a variable power optical system capable of suppressing variation in aberration during power variation or focusing.SOLUTION: A variable power optical system (ZL) includes, in order from the object side, a first lens group (G1) having a positive refractive power, a second lens group (G2) having a negative refractive power, a third lens group (G3) having a positive refractive power, a fourth lens group (G4) having a positive refractive power, and a rear lens group (GR), wherein the rear lens group (GR) includes, in order from the object side, a fifth lens group (G5), a sixth lens group (G6), and a seventh lens group (G7), the interval between adjacent lens groups is changed in order to vary the power, and the rear lens group (GR) includes a focusing lens group that moves during focusing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a variable magnification optical system and an optical instrument using the same. [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 variable magnification optical systems, it is required to suppress fluctuations in aberrations during magnification change or focusing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-160944 A Summary of the Invention

[0004] A variable power optical system according to a first aspect includes, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a subsequent lens group. The subsequent lens group includes, in order from the object side, a fifth lens group, a sixth lens group, and a seventh lens group. During magnification change, the intervals between adjacent lens groups change, and the first lens group, the third lens group, and the fourth lens group move along the optical axis. and when changing magnification from the wide-angle end state to the telephoto end state, the seventh lens group moves along the optical axis toward the object side, the subsequent lens group has two focusing lens groups that move during focusing, the focusing lens groups consist of three or less single lenses, the first lens group consists of, in order from the object side, a first lens having negative refractive power, a second lens having positive refractive power, and a third lens having positive refractive power, an aperture stop is disposed on the object side of the third lens group, and the following conditional expression is satisfied: 0.353≦f3 / f4<2.10 0.010 <dP1 / f1<0.075 where f3 is the focal length of the third lens group. f4: focal length of the fourth lens group dP1: the sum of the center thickness of the first lens and the center thickness of the second lens f1: focal length of the first lens group

[0005] An optical device according to a second aspect is configured by mounting 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, 2B, and 2C 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, the intermediate focal length state, and the telephoto end state, respectively. [Diagram 3] 3A, 3B, and 3C are diagrams showing various aberrations of the variable magnification optical system according to Example 1 when focusing on a close object in the wide-angle end state, the intermediate focal length 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, 5B, and 5C are diagrams showing various aberrations of the variable magnification optical system according to Example 2 when focused on infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. [Figure 6] 6A, 6B, and 6C are diagrams showing various aberrations of the variable magnification optical system according to Example 2 when focusing on a close object in the wide-angle end state, the intermediate focal length 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, 8B, and 8C 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, the intermediate focal length state, and the telephoto end state, respectively. [Figure 9]9A, 9B, and 9C are diagrams showing various aberrations of the variable magnification optical system according to Example 3 when focusing on a close object in the wide-angle end state, the intermediate focal length 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, 11B, and 11C 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, the intermediate focal length state, and the telephoto end state, respectively. [Figure 12] 12A, 12B, and 12C are diagrams showing various aberrations of the variable magnification optical system according to Example 4 when focusing on a close object in the wide-angle end state, the intermediate focal length 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, 14B, and 14C 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, the intermediate focal length state, and the telephoto end state, respectively. [Figure 15] 15A, 15B, and 15C 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, the intermediate focal length 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, 17B, and 17C 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, the intermediate focal length state, and the telephoto end state, respectively. [Figure 18] 18A, 18B, and 18C are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focusing on a close object in the wide-angle end state, the intermediate focal length 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, 20B, and 20C are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focused on infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. [Figure 21] 21A, 21B, and 21C 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, the intermediate focal length 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] The variable magnification optical system and optical device according to this embodiment will be described below with reference to the drawings. First, a camera (optical device) equipped with the variable magnification optical system according to this embodiment will be described with reference to FIG. 22. This camera 1 is a digital camera equipped with the variable magnification optical system according to this embodiment as a photographing lens 2 as shown in FIG. 22. In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and reaches the image sensor 3. As a result, the light from the subject is imaged by the image sensor 3 and recorded as a subject image in a memory (not shown). In this way, the photographer can photograph the subject using the camera 1. This camera may be a mirrorless camera or a single-lens reflex type camera having a quick-return mirror.

[0008] Next, a variable magnification optical system (photographing lens) according to this embodiment will be described. As shown in FIG. 1, the variable magnification optical system ZL(1) as an example of the variable magnification optical system (zoom lens) ZL according to this embodiment has, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a rear lens group GR, and is configured so that the interval between adjacent lens groups changes during magnification. The rear lens group GR has a focusing lens group that moves during focusing. The third lens group G3 is composed of at least one lens having a positive refractive power.

[0009] The variable magnification optical system ZL according to this embodiment has at least five lens groups, and the intervals between the lens groups change during magnification. As a result, according to this embodiment, it is possible to suppress the fluctuation of aberration during magnification change from the wide-angle end state to the telephoto end state. In addition, by arranging the focusing lens group in the subsequent lens group GR, it is possible to make the focusing lens group small and lightweight, and it is possible to realize high-speed and quiet autofocus without increasing the size of the lens barrel. In addition, by configuring the third lens group G3 with a lens having a positive refractive power, it is possible to correct spherical aberration in the telephoto end state without increasing the size of the lens barrel.

[0010] 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.

[0011] With the above-mentioned configuration, the variable magnification optical system ZL according to this embodiment satisfies the following conditional expression (1).

[0012] 0.20 <f3 / f4<2.50 ···(1) where f3 is the focal length of the third lens group G3 f4: Focal length of the fourth lens group G4

[0013] Conditional expression (1) defines the ratio of the focal length of the third lens group G3 to the focal length of the fourth lens group G4. By satisfying conditional expression (1), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

[0014] If the corresponding value of conditional expression (1) exceeds the upper limit, the refractive power of the fourth lens group G4 becomes too strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, during zooming. By setting the upper limit of conditional expression (1) to 2.40, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the upper limit of conditional expression (1) may be set to 2.30, 2.20, 2.10, 2.00, 1.90, 1.80, 1.50, 1.30, 1.00, or even 0.90.

[0015] If the corresponding value of conditional expression (1) falls below the lower limit, the refractive power of the third lens group G3 becomes too strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, during zooming. By setting the lower limit of conditional expression (1) to 0.22, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the lower limit of conditional expression (1) may be set to 0.25, 0.28, 0.30, 0.31, 0.32, 0.33, or even 0.34.

[0016] In the variable magnification optical system ZL according to this embodiment, the third lens group G3 is preferably composed of, in order from the object side, a 31st lens having a positive refractive power and a 32nd lens having a positive refractive power, which makes it possible to effectively correct spherical aberration in the telephoto end state without increasing the size of the lens barrel.

[0017] In the variable magnification optical system ZL according to this embodiment, the first lens group G1 has, in order from the object side, an eleventh lens having negative refractive power and a twelfth lens having positive refractive power, and it is desirable for the first lens group G1 to satisfy the following conditional expression (2):

[0018] 0.010 <dP1 / f1<0.075 ···(2) where dP1 is the sum of the center thickness of the 11th lens and the center thickness of the 12th lens. f1: focal length of the first lens group G1

[0019] Conditional expression (2) defines the ratio of the sum of the center thickness of the 11th lens and the center thickness of the 12th lens to the focal length of the first lens group G1. By satisfying conditional expression (2), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

[0020] If the corresponding value of conditional expression (2) exceeds the upper limit, the refractive power of the first lens group G1 becomes too strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, during zooming. By setting the upper limit of conditional expression (2) to 0.074, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the upper limit of conditional expression (2) may be set to 0.072, 0.070, 0.069, 0.068, 0.067, or even 0.066.

[0021] If the corresponding value of conditional expression (2) falls below the lower limit, the refractive power of the first lens group G1 becomes too weak, and the lens barrel becomes large. In addition, it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, during zooming. By setting the lower limit of conditional expression (2) to 0.015, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the lower limit of conditional expression (2) may be set to 0.020, 0.025, 0.030, 0.033, 0.035, 0.038, or even 0.040.

[0022] In the variable magnification optical system ZL according to this embodiment, it is desirable for the focusing lens group to be composed of three or less single lenses, which allows the focusing lens group to be made smaller and lighter.

[0023] In the variable magnification optical system ZL according to this embodiment, it is desirable that at least one of the focusing lens groups has a single lens with negative refractive power, which can suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a close object.

[0024] In the variable magnification optical system ZL according to this embodiment, it is desirable to arrange the focusing lens group closer to the image side than the aperture stop S. This makes it possible to reduce the size and weight of the focusing lens group.

[0025] In the variable magnification optical system ZL according to this embodiment, it is desirable to arrange at least four lens groups closer to the image side than the aperture stop S. This makes it possible to suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

[0026] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (3).

[0027] 0.20<|fF| / ft<4.00 (3) where fF is the focal length of the focusing lens group with the strongest refractive power. ft: focal length of the variable magnification optical system ZL at the telephoto end

[0028] Conditional expression (3) defines the ratio between the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups and the focal length of the variable magnification optical system ZL in the telephoto end state. By satisfying conditional expression (3), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance, without increasing the size of the lens barrel.

[0029] If the corresponding value of conditional expression (3) exceeds the upper limit, the refractive power of the focusing lens group becomes too weak, so the amount of movement of the focusing lens group during focusing increases, and the lens barrel becomes large. By setting the upper limit of conditional expression (3) to 3.80, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the upper limit of conditional expression (3) may be set to 3.60, 3.40, 3.20, 3.00, 2.80, 2.60, 2.40, 2.20, or even 2.00.

[0030] If the corresponding value of conditional expression (3) falls below the lower limit, the refractive power of the focusing lens group becomes too strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, during focusing. By setting the lower limit of conditional expression (3) to 0.23, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the lower limit of conditional expression (3) may be set to 0.25, 0.28, 0.30, 0.33, or even 0.35.

[0031] In the variable magnification optical system ZL according to this embodiment, it is preferable that the fourth lens group G4 has a cemented lens of a negative lens and a positive lens, which can suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

[0032] In the variable magnification optical system ZL according to this embodiment, the fourth lens group G4 has a cemented lens of a negative lens and a positive lens, and it is desirable to satisfy the following conditional expression (4).

[0033] 1.00 <nN / nP<1.35 ···(4) where nN is the refractive index of the negative lens in the cemented lens. nP: Refractive index of the positive lens in the cemented lens

[0034] Condition (4) defines the ratio of the refractive index of the negative lens to the refractive index of the positive lens in the cemented lens in the fourth lens group G4. By satisfying condition (4), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when zooming from the wide-angle end state to the telephoto end state.

[0035] If the corresponding value of conditional expression (4) exceeds the upper limit, the refractive power of the negative lens in the cemented lens becomes too strong, so that the spherical aberration in the telephoto end state is overcorrected, and it becomes difficult to suppress the fluctuation of various aberrations, including the spherical aberration, when changing the magnification from the wide-angle end state to the telephoto end state. By setting the upper limit of conditional expression (4) to 1.33, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, the upper limit of conditional expression (4) may be set to 1.30, 1.29, 1.28, 1.27, 1.26, or even 1.25.

[0036] If the corresponding value of conditional expression (4) falls below the lower limit, the refractive power of the negative lens in the cemented lens becomes too weak, so that the correction of spherical aberration in the telephoto end state is insufficient, and it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, when changing the magnification from the wide-angle end state to the telephoto end state. By setting the lower limit of conditional expression (4) to 1.02, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, the lower limit of conditional expression (4) may be set to 1.05, 1.08, 1.10, 1.11, 1.12, 1.13, 1.14, or 1.15.

[0037] In the variable magnification optical system ZL according to this embodiment, the fourth lens group G4 has a cemented lens of a negative lens and a positive lens, and it is desirable to satisfy the following conditional expression (5).

[0038] 0.20<νN / νP<0.85 (5) where νN is the Abbe number of the negative lens in the cemented lens. νP: Abbe number of the positive lens in the cemented lens

[0039] Condition (5) defines the ratio of the Abbe number of the negative lens to the Abbe number of the positive lens in the cemented lens in the fourth lens group G4. By satisfying condition (5), chromatic aberration can be corrected well.

[0040] When the corresponding value of conditional expression (5) exceeds the upper limit, the Abbe number of the positive lens in the cemented lens becomes small, so that chromatic aberration occurs excessively, and it becomes difficult to correct the chromatic aberration. By setting the upper limit of conditional expression (5) to 0.83, the effect of this embodiment can be more certain. To further ensure the effect of this embodiment, the upper limit of conditional expression (5) may be set to 0.80, 0.78, 0.75, 0.73, 0.70, 0.68, 0.65, 0.63, 0.60, 0.58, 0.55, 0.53, or even 0.50.

[0041] If the corresponding value of conditional expression (5) falls below the lower limit, the Abbe number of the negative lens in the cemented lens becomes small, resulting in overcorrection of chromatic aberration. By setting the lower limit of conditional expression (5) to 0.22, the effect of this embodiment can be more assured. To further ensure the effect of this embodiment, the lower limit of conditional expression (5) may be set to 0.24, 0.25, 0.26, 0.27, 0.28, or even 0.29.

[0042] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (6).

[0043] f1 / |fRw|<5.00 (6) where f1 is the focal length of the first lens group G1 fRw: focal length of the rear lens group GR in the wide-angle end state

[0044] Conditional expression (6) defines the ratio of the focal length of the first lens group G1 to the focal length of the rear lens group GR in the wide-angle end state. By satisfying conditional expression (6), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

[0045] If the corresponding value of conditional expression (6) exceeds the upper limit, the refractive power of the rear lens group GR becomes too strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, during zooming. By setting the upper limit of conditional expression (6) to 4.80, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the upper limit of conditional expression (6) may be set to 4.60, 4.40, 4.20, 4.00, 3.80, 3.50, 3.00, 2.80, 2.50, 2.30, 2.00, 1.80, or even 1.50.

[0046] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (7).

[0047] 2ωw>75° (7) where ωw is the half angle of view of the variable magnification optical system ZL in the wide-angle end state.

[0048] Conditional expression (7) defines the half angle of view of the variable magnification optical system ZL in the wide-angle end state. By satisfying conditional expression (7), it is possible to suppress the variation in aberration when changing magnification from the wide-angle end state to the telephoto end state while having a wide angle of view. By setting the lower limit value of conditional expression (7) to 76°, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the lower limit value of conditional expression (7) may be set to 77°, 78°, 79°, 80°, 81°, or even 82°.

[0049] It is desirable for the variable magnification optical system ZL according to this embodiment to satisfy the following conditional expression (8).

[0050] 0.10 <BFw / fw<1.00 ···(8) Where, BFw: back focus of the variable magnification optical system ZL in the wide-angle end state fw: focal length of the variable magnification optical system ZL at the wide-angle end

[0051] Condition (8) defines the ratio 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 condition (8), various aberrations including coma in the wide-angle end state can be effectively corrected.

[0052] If the corresponding value of conditional expression (8) exceeds the upper limit, the back focus becomes too 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 aberration, in the wide-angle end state. By setting the upper limit of conditional expression (8) to 0.95, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the upper limit of conditional expression (8) may be set to 0.90, 0.85, 0.80, 0.78, 0.75, 0.73, 0.70, 0.68, or even 0.65.

[0053] If the corresponding value of conditional expression (8) falls below the lower limit, the back focus becomes too 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 (8) to 0.15, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, the lower limit of conditional expression (8) may be set to 0.20, 0.25, 0.30, 0.35, 0.37, 0.38, 0.40, 0.42, 0.44, or even 0.45.

[0054] In the variable magnification optical system ZL according to this embodiment, when the focusing lens group has positive refractive power, it is desirable to satisfy the following conditional expression (9).

[0055] 0.00<(rR2+rR1) / (rR2-rR1)<8.00 ···(9) where rR1 is the radius of curvature of the lens surface on the object side of the lens arranged closest to the image side in the variable magnification optical system ZL. rR2: radius of curvature of the image-side lens surface of the lens located closest to the image side in the variable magnification optical system ZL

[0056] Conditional formula (9) defines the shape factor of the lens located closest to the image side in the variable magnification optical system ZL. By satisfying conditional formula (9), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

[0057] If the corresponding value of conditional expression (9) exceeds the upper limit, the lens arranged closest to the image side of the variable magnification optical system ZL will not be able to correct coma aberration sufficiently, making it difficult to suppress the fluctuation of various aberrations during magnification. By setting the upper limit of conditional expression (9) to 7.50, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the upper limit of conditional expression (9) may be set to 7.00, 6.80, 6.50, 6.30, 6.00, 5.80, 5.50, 5.30, or even 5.00.

[0058] If the corresponding value of conditional expression (9) falls below the lower limit, the lens arranged closest to the image side of the variable magnification optical system ZL will not be able to correct coma aberration sufficiently, making it difficult to suppress the fluctuation of various aberrations during magnification change. By setting the lower limit of conditional expression (9) to 0.10, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the lower limit of conditional expression (9) may be set to 0.50, 0.80, 1.00, 1.20, 1.50, 1.80, 2.00, 2.20, or even 2.50.

[0059] In the variable magnification optical system ZL according to this embodiment, when the focusing lens group has negative refractive power, it is desirable to satisfy the following conditional expression (10).

[0060] -4.00<(rR2+rR1) / (rR2-rR1)<4.00 ···(10) where rR1 is the radius of curvature of the lens surface on the object side of the lens arranged closest to the image side in the variable magnification optical system ZL. rR2: radius of curvature of the image-side lens surface of the lens located closest to the image side in the variable magnification optical system ZL

[0061] Condition (10) defines the shape factor of the lens located closest to the image side in the variable magnification optical system ZL. By satisfying condition (10), it is possible to suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

[0062] If the corresponding value of conditional expression (10) exceeds the upper limit, the lens arranged closest to the image side of the variable magnification optical system ZL will not be able to correct coma aberration sufficiently, making it difficult to suppress the fluctuation of various aberrations during magnification. By setting the upper limit of conditional expression (10) to 3.80, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the upper limit of conditional expression (10) may be set to 3.50, 3.30, 3.00, 2.80, 2.50, 2.30, 2.00, 1.80, or even 1.50.

[0063] If the corresponding value of conditional expression (10) falls below the lower limit, the lens arranged closest to the image side of the variable magnification optical system ZL will not be able to correct coma aberration, making it difficult to suppress the fluctuation of various aberrations during magnification. By setting the lower limit of conditional expression (10) to -3.80, the effect of this embodiment can be made more certain. To make the effect of this embodiment more certain, the lower limit of conditional expression (10) may be set to -3.50, -3.30, -3.00, -2.80, -2.50, -2.30, -2.00, -1.80, or even -1.50.

[0064] Next, a manufacturing method of the variable magnification optical system ZL according to this embodiment will be outlined with reference to FIG. 23. First, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a rear lens group GR are arranged (step ST1). Then, the arrangement is made so that the interval between adjacent lens groups changes during magnification (step ST2). In addition, a focusing lens group that moves during focusing is arranged in the rear lens group GR, and at least one lens having a positive refractive power is arranged in the third lens group G3 (step ST3). Furthermore, each lens is arranged in the lens barrel so as to satisfy at least the above conditional formula (1) (step ST4). This manufacturing method makes it possible to produce a variable magnification optical system that can achieve high-speed, quiet autofocus without increasing the size of the lens barrel, and that suppresses fluctuations in aberration when changing magnification from the wide-angle end state to the telephoto end state, and when focusing from an object at infinity to an object at a close distance. EXAMPLES

[0065] The variable magnification optical system ZL according to each embodiment will be described below with reference to the drawings. Figs. 1, 4, 7, 10, 13, 16, and 19 are cross-sectional views showing the configuration and refractive power distribution of the variable magnification optical system ZL {ZL(1)-ZL(7)} according to the first to seventh embodiments. The first to seventh embodiments correspond to this embodiment. In each cross-sectional view, the movement direction 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. Furthermore, the movement direction of the focusing lens group when focusing from infinity to a close-distance object is indicated by an arrow together with the word "focusing".

[0066] In these figures (FIGS. 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.

[0067] 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.

[0068] 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 last lens surface on the optical axis when focused at infinity plus BF, and BF is the air-equivalent distance (back focus) from the last lens surface on the optical axis to image plane I when focused at infinity. Note that these values ​​are shown for each of the magnification change states: wide-angle end (W), mid-focal length (M), and telephoto end (T). Also, in the [Overall Specifications] table, fRw is the focal length of the subsequent lens group at the wide-angle end.

[0069] 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 (aperture S) indicates an aperture stop. The refractive index of air, nd=1.00000, has been omitted. If the lens 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.

[0070] 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 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.

[0071] 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 +A12×y 12 (A)

[0072] The [Lens Group Data] table shows the starting surface (the surface closest to the object) and focal length of each lens group.

[0073] The [Variable Distance Data] table shows the surface spacing for the surface numbers that are marked as "variable" in the [Lens Specifications] table. The surface spacing is shown here for each magnification state at the wide-angle end (W), mid-focal length (M), and telephoto end (T) when focused at infinity and close distances.

[0074] The table "Conditional Expression Corresponding Values" shows the values ​​corresponding to each conditional expression.

[0075] 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.

[0076] The above explanation of the tables is common to all the embodiments, and therefore, duplicate explanations will be omitted below.

[0077] (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, arranged in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. 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 in the directions indicated by the arrows in FIG. 1, and the intervals between the adjacent lens groups change. The lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the rear lens group GR and has a negative refractive power as a whole. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this is the same in all the following examples.

[0078] The first lens group G1 is composed of, in order from the object side, 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. The negative meniscus lens L11 corresponds to the 11th lens. The positive meniscus lens L12 corresponds to the 12th lens.

[0079] The second lens group G2 is composed of, arranged in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, 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.

[0080] The third lens group G3 is composed of, arranged in order from the object side, a positive meniscus lens L31 with a convex surface facing the object side, and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during magnification. The positive meniscus lens L31 corresponds to the 31st lens, and its lens surface on the object side is aspheric. The positive lens L32 corresponds to the 32nd lens.

[0081] 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.

[0082] The fifth lens group G5 is composed of, arranged in order from the object side, a negative meniscus lens L51 with a concave surface facing the object side, and a biconvex positive lens L52.

[0083] 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.

[0084] The seventh lens group G7 is composed of, in order from the object side, a positive meniscus lens L71 with a concave surface facing the object side, a biconcave negative lens L72, and a negative meniscus lens L73 with a concave surface facing the object side. The lens surface facing the object side of the negative lens L72 is aspheric. An image surface I is disposed on the image side of the seventh lens group G7.

[0085] In this embodiment, the fifth lens group G5 and the sixth lens group G6 are moved independently toward the object side to focus from a long distance object to a close distance object (from an infinitely distant object to a finite distance object). That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

[0086] Table 1 below lists the values ​​of the specifications of the variable magnification optical system according to the first example.

[0087] (Table 1) [Overall specifications] Magnification ratio: 2.74 fRw=-4993.677 WMT f 24.8 50.0 67.9 FNO 2.92 2.92 2.92 2ω 85.10 45.26 33.84 Ymax 21.60 21.60 21.60 TL 139.35 158.45 169.16 BF 11.93 23.42 28.62 [Lens specifications] Surface number RD nd νd Object plane ∞ 1 234.3873 2.500 1.84666 23.80 2 109.5180 5.200 1.75500 52.34 3 389.6852 0.200 4 59.0627 5.700 1.77250 49.62 5 135.3649 D5(variable) 6* 218.4420 2.000 1.74389 49.53 7 18.6957 9.658 8 -59.6856 1.300 1.77250 49.62 9 59.6856 0.442 10 39.2099 6.400 1.72825 28.38 11 -48.6731 1.933 12 -26.4065 1.300 1.61800 63.34 13 -71.7612 D13(variable) 14 ∞ 1.712 (Aperture S) 15* 71.8876 2.500 1.69370 53.32 16 127.6411 0.716 17 38.7492 5.900 1.59319 67.90 18 -105.4274 D18(variable) 19 67.0276 1.300 1.73800 32.33 20 19.5126 9.700 1.49782 82.57 21 -50.5609 D21(variable) 22 -23.9237 1.200 1.72047 34.71 23 -56.2081 0.200 24 103.1749 5.900 1.59349 67.00 25 -33.0197 D25(variable) 26 -70.6288 3.500 1.79189 45.04 27* -38.2153 D27(variable) 28 -43.9824 3.000 1.94595 17.98 29 -32.4253 0.200 30* -100.5837 1.500 1.85207 40.15 31 88.1634 7.847 32 -25.2838 1.400 1.58913 61.22 33 - 45.3661 BF Image plane ∞ [Aspherical data] The 6th surface κ = 1.0000, A4 = 5.27866E - 06, A6 = - 5.41835E - 09 A8 = 1.33113E - 11, A10 = - 2.04736E - 14, A12 = 2.05090E - 17 The 15th surface κ = 1.0000, A4 = - 4.55747E - 06, A6 = - 1.40092E - 10 A8 = - 8.81384E - 13, A10 = - 8.42653E - 15, A12 = 0.00000E + 00 The 27th surface κ = 1.0000, A4 = 1.09543E - 05, A6 = - 2.36281E - 08 A8 = 1.42728E - 10, A10 = - 5.02724E - 13, A12 = 7.51800E - 16 The 30th surface κ = 1.0000, A4 = - 2.18913E - 06, A6 = - 2.29301E - 08 A8 = 3.94582E - 11, A10 = - 9.84200E - 14, A12 = 0.00000E + 00 [Lens group data] Group Starting surface Focal length G1 1 119.124 G2 6 - 22.126 G3 14 40.880 G4 19 115.687 G5 22 124.717 G6 26 100.365 G7 28 - 47.354 [Variable interval data] W M T W M T Infinity Infinity Infinity Close distance Close distance Close distance D5 1.780 21.220 30.246 1.780 21.220 30.246 D13 19.285 6.132 2.013 19.285 6.132 2.013 D18 9.167 3.866 1.493 9.167 3.866 1.493 D21 5.179 14.279 19.018 4.137 12.991 17.666 D25 2.679 3.515 2.616 3.249 4.079 3.027 D27 6.128 2.807 1.953 6.600 3.530 2.893 [Conditional expression corresponding value] Conditional expression (1) f3 / f4=0.353 Conditional expression (2) dP1 / f1=0.065 Conditional expression (3) |fF| / ft=1.837 Conditional expression (4) nN / nP=1.160 Conditional expression (5) νN / νP=0.392 Conditional expression (6) f1 / |fRw|=0.024 Conditional expression (7) 2ωw=85.10 Conditional expression (8) BFw / fw=0.482 Conditional expression (9) (rR2+rR1) / (rR2-rR1)=3.518

[0088] Figures 2(A), 2(B), and 2(C) are diagrams showing various aberrations when the variable magnification optical system according to Example 1 is focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. Figures 3(A), 3(B), and 3(C) are diagrams showing various aberrations when the variable magnification optical system according to Example 1 is focused on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

[0089] In each of the aberration diagrams in Fig. 2(A) to Fig. 2(C), FNO indicates the F-number, and Y indicates the image height. In the spherical aberration diagram, the F-number value corresponding to the maximum aperture is shown, in the astigmatism diagram and the distortion diagram, the maximum image height is shown, and in the lateral aberration diagram, the value of each image height is shown. In each of the aberration diagrams in Fig. 3(A) to Fig. 3(C), NA indicates the numerical aperture, and Y indicates the image height. In the spherical aberration diagram, the numerical aperture value corresponding to the maximum aperture is shown, in the astigmatism diagram and the distortion diagram, the maximum image height is shown, and in the lateral aberration diagram, the value of each image height is shown. In addition, in each of the aberration diagrams, 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 plane, and the dashed line indicates the meridional image plane. In the aberration diagrams of the following examples, the same reference numerals as in this example are used, and duplicated explanations will be omitted.

[0090] It can be seen from each of the aberration diagrams that the variable magnification optical system of Example 1 has excellent imaging performance with excellent correction of aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on close objects.

[0091] (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, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. 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 in the directions indicated by the arrows in FIG. 4, and the intervals between the adjacent lens groups change. The lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the rear lens group GR, and has negative refractive power as a whole.

[0092] The first lens group G1 is composed of, in order from the object side, 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. The negative meniscus lens L11 corresponds to the 11th lens. The positive meniscus lens L12 corresponds to the 12th lens.

[0093] The second lens group G2 is composed of, arranged in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, 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.

[0094] 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. The aperture stop S is provided near the object side of the third lens group G3 and moves together with the third lens group G3 during zooming. The positive lens L31 corresponds to the 31st lens, and its lens surface on the object side is aspheric. The positive lens L32 corresponds to the 32nd lens.

[0095] 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.

[0096] The fifth lens group G5 is composed of, arranged in order from the object side, a negative meniscus lens L51 with a concave surface facing the object side, and a biconvex positive lens L52.

[0097] 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.

[0098] The seventh lens group G7 is composed of, in order from the object side, a positive meniscus lens L71 with a concave surface facing the object side, a biconcave negative lens L72, and a negative meniscus lens L73 with a concave surface facing the object side. The lens surface facing the object side of the negative lens L72 is aspheric. An image surface I is disposed on the image side of the seventh lens group G7.

[0099] In this embodiment, the fifth lens group G5 and the sixth lens group G6 are moved independently toward the object side to focus from a long distance object to a close distance object (from an infinitely distant object to a finite distance object). That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

[0100] Table 2 below lists the values ​​of the specifications of the variable magnification optical system according to the second example.

[0101] (Table 2) [Overall specifications] Magnification ratio: 2.74 fRw=-346.533 WMT f 24.8 50.0 67.9 FNO 2.92 2.92 2.92 2ω 85.08 45.32 33.84 Ymax 21.60 21.60 21.60 TL 139.96 156.15 168.00 BF 11.76 26.07 29.33 [Lens specifications] Surface number RD nd νd Object plane ∞ 1 282.3733 2.500 1.84666 23.80 2 123.2365 5.647 1.77250 49.62 3 1180.1775 0.200 4 59.2907 4.310 1.81600 46.59 5 98.9987 D5 (variable) 6* 205.3191 2.000 1.74389 49.53 7 19.2200 9.185 8 -74.7032 1.300 1.83481 42.73 9 64.3697 0.324 10 41.9771 5.683 1.78472 25.64 11 -72.0408 4.071 12 -26.6709 1.300 1.60300 65.44 13 -52.5345 D13(variable) 14 ∞ 1.500 (Aperture S) 15* 84.6431 3.039 1.58913 61.15 16 -4073.6051 0.200 17 42.4140 5.438 1.59319 67.90 18 -143.7473 D18(variable) 19 74.9775 1.300 1.73800 32.33 20 20.9860 9.090 1.49782 82.57 21 -48.9247 D21(variable) 22 -23.9603 1.200 1.73800 32.33 23 -52.8529 0.955 24 113.2572 5.800 1.59349 66.99 25 -32.1120 D25(variable) 26 -120.6162 3.500 1.74389 49.53 27* -50.8923 D27(variable) 28 -61.4253 3.215 1.94595 17.98 29 -34.3446 0.200 30* -69.3409 1.500 1.85108 40.12 31 72.0715 6.683 32 -23.1150 1.400 1.69680 55.52 33 - 36.7553 BF Image plane ∞ [Aspherical data] The 6th surface κ = 1.0000, A4 = 4.34838E - 06, A6 = -2.30274E - 09 A8 = 1.34342E - 12, A10 = 2.08876E - 15, A12 = 0.00000E + 00 The 15th surface κ = 1.0000, A4 = -4.08736E - 06, A6 = 2.82731E - 09 A8 = -1.71368E - 11, A10 = 2.81580E - 14, A12 = 0.00000E + 00 The 27th surface κ = 1.0000, A4 = 9.77330E - 06, A6 = -1.31611E - 08 A8 = 7.02329E - 11, A10 = -1.28887E - 13, A12 = 0.00000E + 00 The 30th surface κ = 1.0000, A4 = -3.68898E - 06, A6 = -1.92901E - 08 A8 = 3.36794E - 11, A10 = -8.19805E - 14, A12 = 0.00000E + 00 [Lens group data] Group Starting surface Focal length G1 1 133.226 G2 6 -23.579 G3 14 40.561 G4 19 115.254 G5 22 113.536 G6 26 115.868 G7 28 -42.726 [Variable interval data] W M T W M T Infinity Infinity Infinity Close distance Close distance Close distance D5 2.000 18.194 30.046 2.000 18.194 30.046 D13 21.479 6.645 2.000 21.479 6.645 2.000 D18 9.801 4.462 1.500 9.801 4.462 1.500 D21 5.195 13.414 18.760 4.220 12.328 17.590 D25 2.295 3.824 2.737 2.742 4.222 2.950 D27 5.890 2.000 2.087 6.417 2.689 3.043 [Conditional expression corresponding value] Conditional expression (1) f3 / f4=0.352 Conditional expression (2) dP1 / f1=0.061 Conditional expression (3) |fF| / ft=1.706 Conditional expression (4) nN / nP=1.160 Conditional expression (5) νN / νP=0.392 Conditional expression (6) f1 / |fRw|=0.384 Conditional expression (7) 2ωw=85.08 Conditional expression (8) BFw / fw=0.475 Conditional expression (9) (rR2+rR1) / (rR2-rR1)=4.389

[0102] Fig. 5(A), Fig. 5(B), and Fig. 5(C) are diagrams showing various aberrations of the variable magnification optical system according to the second embodiment when focusing on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. Fig. 6(A), Fig. 6(B), and Fig. 6(C) are diagrams showing various aberrations of the variable magnification optical system according to the second embodiment when focusing on a close distance in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. From each diagram of various aberrations, it can be seen that the variable magnification optical system according to the second embodiment has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and further has excellent imaging performance when focusing on a close distance.

[0103] (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, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. 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 in the directions indicated by the arrows in FIG. 7, and the intervals between the adjacent lens groups change. The lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the rear lens group GR, and has negative refractive power as a whole.

[0104] The first lens group G1 is composed of, in order from the object side, 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. The negative meniscus lens L11 corresponds to the 11th lens. The positive lens L12 corresponds to the 12th lens.

[0105] The second lens group G2 is composed of, arranged in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, 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, a positive meniscus lens L31 with a convex surface facing the object side, and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during magnification. The positive meniscus lens L31 corresponds to the 31st lens, and its lens surface on the object side is aspheric. The positive lens L32 corresponds to the 32nd lens.

[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, arranged in order from the object side, a negative meniscus lens L51 with a concave surface facing the object side, and a biconvex positive lens L52.

[0109] 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.

[0110] The seventh lens group G7 is composed of, in order from the object side, a negative meniscus lens L71 with a convex surface facing the object side, a positive meniscus lens L72 with a concave surface facing the object side, and a negative meniscus lens L73 with a concave surface facing the object side. The lens surface facing the object side of the negative meniscus lens L73 is aspheric. An image surface I is disposed on the image side of the seventh lens group G7.

[0111] In this embodiment, the fifth lens group G5 and the sixth lens group G6 are moved independently toward the object side to focus from a long distance object to a close distance object (from an infinitely distant object to a finite distance object). That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

[0112] Table 3 below lists the values ​​of the specifications of the variable magnification optical system according to the third example.

[0113] (Table 3) [Overall specifications] Magnification ratio: 3.33 fRw=-219.096 WMT f 24.8 50.0 82.5 FNO 2.92 2.92 2.92 2ω 85.12 45.44 28.34 Ymax 21.60 21.60 21.60 TL 150.97 164.85 185.45 BF 11.75 21.93 30.78 [Lens specifications] Surface number RD nd νd Object plane ∞ 1 454.1335 2.500 1.94594 17.98 2 158.8346 5.629 1.81600 46.59 3 -1850.8518 0.200 4 62.5732 5.149 1.81600 46.59 5 111.4228 D5(variable) 6* 143.7538 2.000 1.81600 46.59 7 20.1321 9.695 8 -48.3009 2.346 1.88300 40.66 9 156.4679 0.200 10 65.6396 6.565 1.80518 25.45 11 -42.2522 2.354 12 -26.3896 1.200 1.69680 55.52 13 -61.8795 D13(variable) 14 ∞ 1.500 (Aperture S) 15* 46.9137 2.985 1.81600 46.59 16 79.9069 0.200 17 56.4482 6.543 1.49782 82.57 18 -69.0474 D18(variable) 19 78.4165 1.300 1.90366 31.27 20 26.6178 9.263 1.59319 67.90 21 -58.5857 D21(variable) 22 -29.0948 1.200 1.80100 34.92 23 -53.3089 2.957 24 64.8393 6.500 1.48749 70.32 25 -36.2810 D25(variable) 26 -486.6338 2.667 1.58887 61.13 27* -77.9833 D27(variable) 28 208.9420 1.200 1.90366 31.27 29 40.1016 3.903 30 -103.6980 6.199 1.84666 23.80 31 -35.7067 3.104 32* -19.6292 1.500 1.81600 46.59 33 -40.5502 BF Image plane ∞ [Aspheric data] Page 6 κ=1.0000,A4=4.25283E-06,A6=-2.28156E-09 A8=-7.12258E-14,A10=7.16065E-15,A12=0.00000E+00 Page 15 κ=1.0000,A4=-3.75837E-06,A6=9.56813E-10 A8=-1.31531E-12,A10=1.97978E-16,A12=0.00000E+00 Page 27 κ=1.0000,A4=1.09037E-05,A6=-5.09501E-11 A8=-1.76649E-12,A10=1.58609E-14,A12=0.00000E+00 Page 32 κ=1.0000,A4=1.01091E-05,A6=1.61408E-08 A8=3.76726E-12,A10=1.25182E-13,A12=0.00000E+00 [Lens group data] Group starting plane focal length G1 1 130.092 G2 6 -23.049 G3 14 44.414 G4 19 100.000 G5 22 98.812 G6 26 157.320 G7 28 -42.703 [Variable interval data] W M T W M T Infinity Infinity Infinity Close range Close range Close range D5 2.000 21.323 36.906 2.000 21.323 36.906 D13 25.662 7.746 2.000 25.662 7.746 2.000 D18 9.597 5.312 1.500 9.597 5.312 1.500 D21 6.192 11.864 21.415 5.303 10.833 20.070 D25 2.000 3.105 2.000 2.411 3.415 2.346 D27 4.901 4.716 2.000 5.379 5.438 2.999 [Conditional expression corresponding value] Conditional expression (1) f3 / f4 = 0.444 Conditional expression (2) dP1 / f1 = 0.062 Conditional expression (3) |fF| / ft = 1.907 Conditional expression (4) nN / nP = 1.195 Conditional expression (5) νN / νP = 0.461 Conditional expression (6) f1 / |fRw| = 0.594 Conditional expression (7) 2ωw = 85.12 Conditional expression (8) BFw / fw = 0.475 Conditional expression (9) (rR2 + rR1) / (rR2 - rR1) = 2.877

[0114] 8(A), 8(A), and 8(C) are diagrams showing various aberrations of the variable magnification optical system according to Example 3 when focusing on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 9(A), 9(B), and 9(C) are diagrams 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, the intermediate focal length state, and the telephoto end state, respectively. From each diagram of various aberrations, it can be seen that the variable magnification optical system according to Example 3 has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and further has excellent imaging performance when focusing on a close distance.

[0115] (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, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. 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 in the directions indicated by the arrows in FIG. 10, and the intervals between the adjacent lens groups change. The lens group consisting of the fifth lens group G5 and the sixth lens group G6 corresponds to the rear lens group GR and has negative refractive power as a whole.

[0116] The first lens group G1 is composed of, in order from the object side, 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. The negative meniscus lens L11 corresponds to the 11th lens. The positive meniscus lens L12 corresponds to the 12th lens.

[0117] The second lens group G2 is composed of, arranged in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, 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.

[0118] The third lens group G3 is composed of, arranged in order from the object side, a positive meniscus lens L31 with a convex surface facing the object side, and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during magnification. The positive meniscus lens L31 corresponds to the 31st lens, and its lens surface on the object side is aspheric. The positive lens L32 corresponds to the 32nd lens.

[0119] 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.

[0120] The fifth lens group G5 is composed of, in order from the object side, a negative meniscus lens L51 with a concave surface facing the object side, a biconvex positive lens L52, and a positive meniscus lens L53 with a concave surface facing the object side. The positive meniscus lens L53 has an aspheric lens surface facing the image side.

[0121] The sixth lens group G6 is composed of, in order from the object side, a positive meniscus lens L61 with a concave surface facing the object side, a biconcave negative lens L62, and a negative meniscus lens L63 with a concave surface facing the object side. The lens surface facing the object side of the negative lens L62 is aspheric. An image surface I is disposed on the image side of the sixth lens group G6.

[0122] In this embodiment, focusing from a long distance object to a close distance object (from an infinitely distant object to a finite distance object) is performed by moving the fifth lens group G5 toward the object side. In other words, the fifth lens group G5 corresponds to a focusing lens group.

[0123] Table 4 below lists the values ​​of the specifications of the variable magnification optical system according to the fourth example.

[0124] (Table 4) [Overall specifications] Magnification ratio: 2.75 fRw=-356.649 WMT f 24.7 50.0 67.9 FNO 2.92 2.92 2.92 2ω 85.08 45.26 33.84 Ymax 21.60 21.60 21.60 TL 139.95 154.92 168.36 BF 11.75 26.42 30.21 [Lens specifications] Surface number RD nd νd Object plane ∞ 1 500.0000 2.500 1.84666 23.80 2 128.5654 5.629 1.77250 49.62 3 1528.3565 0.200 4 51.0685 4.893 1.81600 46.59 5 84.5957 D5(variable) 6* 150.2756 2.000 1.74389 49.53 7 19.5218 9.332 8 -70.5990 1.300 1.83481 42.73 9 68.8663 0.377 10 44.7171 5.665 1.78472 25.64 11 -66.3119 4.463 12 -25.4625 1.300 1.60300 65.44 13 -54.4747 D13(variable) 14 ∞ 1.500 (Aperture S) 15* 93.5557 2.758 1.58913 61.15 16 731.3943 0.200 17 45.8800 5.212 1.59319 67.90 18 -126.9127 D18(variable) 19 57.2400 1.300 1.73800 32.33 20 21.3782 8.742 1.49782 82.57 21 -52.7685 D21(variable) 22 -23.6692 1.200 1.73800 32.33 23 -59.4644 0.200 24 110.3346 5.800 1.59349 67.00 25 -32.1046 4.444 26 -114.5585 3.326 1.74389 49.53 27* -41.8456 D27(variable) 28 -51.0521 2.929 1.94594 17.98 29 -33.3238 0.200 30* -98.8101 1.500 1.85108 40.12 31 58.4711 6.329 32 -25.4692 1.400 1.69680 55.52 33 -42.7921 BF Image plane ∞ [Aspheric data] Side 6 κ=1.0000,A4=4.65692E-06,A6=-1.64542E-09 A8=3.72186E-13,A10=4.82369E-15,A12=0.00000E+00 Page 15 κ=1.0000,A4=-3.70657E-06,A6=3.18672E-09 A8=-1.82835E-11,A10=3.59863E-14,A12=0.00000E+00 Page 27 κ=1.0000,A4=1.13375E-05,A6=-1.49475E-08 A8 = 6.38011E - 11, A10 = -1.10074E - 13, A12 = 0.00000E + 00 Page 30 κ = 1.0000, A4 = -5.84233E - 06, A6 = -2.49185E - 08 A8 = 2.26680E - 11, A10 = -7.54165E - 14, A12 = 0.00000E + 00 [Lens group data] Group Start Surface Focal Length G1 1 136.259 G2 6 -23.493 G3 14 44.223 G4 19 90.807 G5 22 53.777 G6 28 -40.364 [Variable interval data] W M T W M T Infinity Infinity Infinity Close distance Close distance Close distance D5 2.000 16.966 30.403 2.000 16.966 30.403 D13 20.342 6.266 2.000 20.342 6.266 2.000 D18 10.475 3.778 2.048 10.475 3.778 2.048 D21 4.711 14.758 17.000 4.046 13.957 16.055 D27 5.973 2.030 2.000 6.639 2.831 2.945 [Condition formula corresponding value] Condition formula (1) f3 / f4 = 0.487 Condition formula (2) dP1 / f1 = 0.060 Condition formula (3) |fF| / ft = 0.792 Condition formula (4) nN / nP = 1.160 Condition formula (5) νN / νP = 0.392 Condition formula (6) f1 / |fRw| = 0.382 Condition formula (7) 2ωw = 85.08 Condition formula (8) BFw / fw = 0.475 Conditional expression (9) (rR2+rR1) / (rR2-rR1)=3.941

[0125] Fig. 11(A), Fig. 11(B), and Fig. 11(C) are diagrams showing various aberrations of the variable magnification optical system according to Example 4 when focusing on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. Fig. 12(A), Fig. 12(B), and Fig. 12(C) are diagrams 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, the intermediate focal length state, and the telephoto end state, respectively. From each diagram of various aberrations, it can be seen that the variable magnification optical system according to Example 4 has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and further has excellent imaging performance when focusing on a close distance.

[0126] (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, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. 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 in the directions indicated by the arrows in FIG. 13, and the intervals between the adjacent lens groups change. The lens group consisting of the fifth lens group G5 and the sixth lens group G6 corresponds to the rear lens group GR and has negative refractive power as a whole.

[0127] The first lens group G1 is composed of, in order from the object side, a cemented negative 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. The negative meniscus lens L11 corresponds to the 11th lens. The positive lens L12 corresponds to the 12th lens.

[0128] The second lens group G2 is composed of, arranged in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, 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.

[0129] The third lens group G3 is composed of, arranged in order from the object side, a positive meniscus lens L31 with a convex surface facing the object side, and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during magnification. The positive meniscus lens L31 corresponds to the 31st lens, and its lens surface on the object side is aspheric. The positive lens L32 corresponds to the 32nd lens.

[0130] The fourth lens group G4 is composed of, in order from the object side, a biconvex positive lens L41, a cemented negative lens consisting of a biconcave negative lens L42 and a biconvex positive lens L43, and a biconvex positive lens L44. The positive lens L41 has an aspheric lens surface on the object side. The positive lens L44 has an aspheric lens surface on the image side.

[0131] The fifth lens group G5 includes, in order from the object side, a positive meniscus lens L51 with a concave surface facing the object side, a biconcave negative lens L52, and a biconcave negative lens L53. The object side surface of the negative lens L53 is aspheric.

[0132] The sixth lens group G6 is composed of a biconvex positive lens L61. An image surface I is disposed on the image side of the sixth lens group G6.

[0133] In this embodiment, focusing from a long distance object to a close distance object (from an infinitely distant object to a finite distance object) is performed by moving the fifth lens group G5 toward the image surface I. In other words, the fifth lens group G5 corresponds to a focusing lens group.

[0134] Table 5 below lists the values ​​of the specifications of the variable magnification optical system according to the fifth example.

[0135] (Table 5) [Overall specifications] Magnification ratio: 2.75 fRw=-45.339 WMT f 24.7 50.0 67.9 FNO 2.92 2.92 2.92 2ω 85.16 45.24 34.12 Ymax 21.60 21.60 21.60 TL 134.73 154.61 169.45 BF 13.56 26.94 34.84 [Lens specifications] Surface number RD nd νd Object plane ∞ 1 10957.4900 2.500 1.84666 23.80 2 273.2507 3.923 1.59319 67.90 3 -4164.8091 0.200 4 97.8909 5.850 1.81600 46.59 5 1686.5488 D5(variable) 6* 500.0000 2.000 1.67798 54.89 7 19.6217 7.571 8 -119.4257 1.200 1.59319 67.90 9 74.2767 0.211 10 36.8572 5.028 1.85000 27.03 11 146.1931 4.217 12 -25.9063 1.200 1.60300 65.44 13 -48.3220 D13(variable) 14 ∞ 1.500 (Aperture S) 15* 31.8609 3.346 1.79504 28.69 16 60.3817 1.288 17 65.3208 3.503 1.49782 82.57 18 -22831.8850 D18(variable) 19* 52.1943 4.361 1.82098 42.50 20 -99.8775 0.663 21 -484.1811 1.200 1.85478 24.80 22 19.0497 8.079 1.49782 82.57 23 -86.9834 3.675 24 61.0249 5.155 1.80604 40.74 25* -60.8291 D25(variable) 26 -310.5249 2.912 1.94594 17.98 27 -59.5174 0.200 28 -155.6589 1.200 1.77250 49.62 29 30.4299 6.880 30* -54.7368 1.300 1.95150 29.83 31 317.1233 D31(variable) 32 72.1520 4.819 1.83481 42.73 33 -315.4491 BF Image plane ∞ [Aspheric data] Page 6 κ=1.0000,A4= 5.57412E-06,A6=-5.71627E-09 A8=9.08385E-12,A10=-4.74214E-15,A12=0.00000E+00 Page 15 κ=1.0000,A4=-5.90450E-06,A6=3.98445E-09 A8=-4.29920E-11,A10=9.10161E-14,A12=0.00000E+00 Page 19 κ=1.0000,A4=-5.71112E-06,A6=-6.16170E-10 A8 = 2.42198E-11, A10 = -5.71940E-14, A12 = 0.00000E+00 The 25th surface κ = 1.0000, A4 = 2.37352E-06, A6 = -6.63258E-09 A8 = -2.39696E-11, A10 = 1.99908E-14, A12 = 0.00000E+00 The 30th surface κ = 1.0000, A4 = -6.17314E-06, A6 = -3.26346E-08 A8 = 1.32620E-10, A10 = -6.33629E-13, A12 = 0.00000E+00 [Lens group data] Group Starting surface Focal length G1 1 139.410 G2 6 -23.353 G3 14 51.116 G4 19 31.271 G5 26 -24.892 G6 32 70.741 [Variable interval data] W M T W M T Infinity Infinity Infinity Close distance Close distance Close distance D5 2.000 21.443 31.758 2.000 21.443 31.758 D13 19.908 6.376 2.000 19.908 6.376 2.000 D18 9.100 3.184 2.000 9.100 3.184 2.000 D25 3.162 2.189 2.000 3.569 2.602 2.454 D31 3.023 10.499 12.881 2.616 10.087 12.426 [Conditional formula corresponding values] Conditional formula (1) f3 / f4 = 1.635 Conditional formula (2) dP1 / f1 = 0.046 Conditional formula (3) |fF| / ft = 0.367 Conditional formula (4) nN / nP = 1.238 Conditional expression (5) νN / νP=0.300 Conditional expression (6) f1 / |fRw|=3.075 Conditional expression (7) 2ωw=85.16 Conditional expression (8) BFw / fw=0.548 Conditional expression (10) (rR2+rR1) / (rR2-rR1)=0.628

[0136] Fig. 14(A), Fig. 14(B), and Fig. 14(C) are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focusing on infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. Fig. 15(A), Fig. 15(B), and Fig. 15(C) are diagrams 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, the intermediate focal length state, and the telephoto end state, respectively. From each diagram of various aberrations, it can be seen that the variable magnification optical system according to Example 5 has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and further has excellent imaging performance when focusing on a close distance.

[0137] (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, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having positive refractive power. 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 in the directions indicated by the arrows in FIG. 16, and the intervals between the adjacent lens groups change. The lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the rear lens group GR, and has negative refractive power as a whole.

[0138] The first lens group G1 is composed of, in order from the object side, a cemented negative 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. The negative meniscus lens L11 corresponds to the 11th lens. The positive meniscus lens L12 corresponds to the 12th lens.

[0139] The second lens group G2 is composed of, arranged in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, 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.

[0140] The third lens group G3 is composed of, arranged in order from the object side, a positive meniscus lens L31 with a convex surface facing the object side, and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during magnification. The positive meniscus lens L31 corresponds to the 31st lens, and its lens surface on the object side is aspheric. The positive lens L32 corresponds to the 32nd lens.

[0141] The fourth lens group G4 is composed of, in order from the object side, a biconvex positive lens L41, a cemented negative lens consisting of a biconcave negative lens L42 and a biconvex positive lens L43, and a biconvex positive lens L44. The positive lens L41 has an aspheric lens surface on the object side. The positive lens L44 has an aspheric lens surface on the image side.

[0142] The fifth lens group G5 includes, in order from the object side, a positive meniscus lens L51 with a concave surface facing the object side, a biconcave negative lens L52, and a biconcave negative lens L53. The object side surface of the negative lens L53 is aspheric.

[0143] The sixth lens group G6 is composed of a positive meniscus lens L61 with its convex surface facing the object side.

[0144] 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.

[0145] In this embodiment, focusing from a long distance object to a close distance object (from an infinitely distant object to a finite distance object) is performed by moving the fifth lens group G5 toward the image surface I. In other words, the fifth lens group G5 corresponds to a focusing lens group.

[0146] Table 6 below lists the values ​​of the specifications of the variable magnification optical system according to the sixth example.

[0147] (Table 6) [Overall specifications] Magnification ratio: 2.74 fRw=-40.687 WMT f 24.8 50.0 67.9 FNO 2.96 2.98 2.99 2ω 85.16 45.20 34.12 Ymax 21.60 21.60 21.60 TL 138.57 158.72 174.45 BF 13.13 25.93 34.76 [Lens specifications] Surface number RD nd νd Object plane ∞ 1 800.0000 2.500 1.84666 23.80 2 214.4014 3.846 1.59319 67.90 3 1317.1215 0.200 4 112.4262 5.452 1.81600 46.59 5 6769.9563 D5(variable) 6* 500.0000 2.000 1.67798 54.89 7 20.1483 7.488 8 -122.7141 1.200 1.59319 67.90 9 65.7886 0.272 10 36.9186 6.199 1.85000 27.03 11 167.8314 4.151 12 -26.0907 1.200 1.60300 65.44 13 -47.5468 D13(variable) 14 ∞ 1.500 (Aperture S) 15* 34.4078 3.172 1.79504 28.69 16 61.0992 1.040 17 57.2334 3.808 1.49782 82.57 18 -5887.8063 D18(variable) 19* 56.4489 4.200 1.82098 42.50 20 -110.1792 0.505 21 -291.5983 1.200 1.85478 24.80 22 21.3003 9.632 1.49782 82.57 23 -65.8810 3.027 24 55.5374 5.156 1.80604 40.74 25* -64.8934 D25(variable) 26 -368.5041 2.887 1.94594 17.98 27 -62.4504 0.200 28 -158.4306 1.200 1.77250 49.62 29 31.1763 6.060 30* -91.4544 1.300 1.95150 29.83 31 81.4249 D31(variable) 32 57.0897 2.149 1.80518 25.45 33 69.0085 D33(variable) 34 73.7084 4.702 1.64000 60.19 35 -314.5384 BF Image plane ∞ [Aspheric data] The 6th surface κ = 1.0000, A4 = 4.89442E-06, A6 = -5.03173E-09 A8 = 9.04508E-12, A10 = -5.83062E-15, A12 = 0.00000E+00 The 15th surface κ = 1.0000, A4 = -5.12384E-06, A6 = 3.61548E-09 A8 = -3.66003E-11, A10 = 7.76731E-14, A12 = 0.00000E+00 The 19th surface κ = 1.0000, A4 = -5.21485E-06, A6 = -8.93869E-10 A8 = 2.28848E-11, A10 = -5.34780E-14, A12 = 0.00000E+00 The 25th surface κ = 1.0000, A4 = 3.45860E-06, A6 = -6.25344E-09 A8 = -1.37950E-11, A10 = 2.51017E-14, A12 = 0.00000E+00 The 30th surface κ = 1.0000, A4 = -6.74203E-06, A6 = -2.42770E-08 A8 = 5.92492E-11, A10 = -3.49332E-13, A12 = 0.00000E+00 [Lens group data] Group Starting surface Focal length G1 1 152.425 G2 6 -24.007 G3 14 52.775 G4 19 30.001 G5 26 -24.147 G6 32 379.967 G7 34 93.748 [Variable interval data] W M T W M T Infinity Infinity Infinity Close distance Close distance Close distance D5 2.000 22.083 33.118 2.000 22.083 33.118 D13 20.464 6.484 2.000 20.464 6.484 2.000 D18 9.842 3.320 2.000 9.842 3.320 2.000 D25 2.978 2.225 2.053 3.339 2.586 2.447 D31 2.915 10.198 13.200 2.555 9.837 12.806 D33 1.000 2.234 1.084 1.000 2.234 1.084 [Conditional expression corresponding value] Conditional expression (1) f3 / f4=1.759 Conditional expression (2) dP1 / f1=0.042 Conditional expression (3) |fF| / ft=0.356 Conditional expression (4) nN / nP=1.238 Conditional expression (5) νN / νP=0.300 Conditional expression (6) f1 / |fRw|=3.746 Conditional expression (7) 2ωw=85.16 Conditional expression (8) BFw / fw=0.530 Conditional expression (10) (rR2+rR1) / (rR2-rR1)=0.620

[0148] Fig. 17(A), Fig. 17(B), and Fig. 17(C) are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focusing on infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. Fig. 18(A), Fig. 18(B), and Fig. 18(C) are diagrams 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, the intermediate focal length state, and the telephoto end state, respectively. From each diagram of various aberrations, it can be seen that the variable magnification optical system according to Example 6 has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and further has excellent imaging performance when focusing on a close distance.

[0149] (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, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. 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 in the directions indicated by the arrows in FIG. 19, and the intervals between the adjacent lens groups change. The lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the rear lens group GR, and has positive refractive power as a whole.

[0150] The first lens group G1 is composed of, in order from the object side, 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. The negative meniscus lens L11 corresponds to the 11th lens. The positive meniscus lens L12 corresponds to the 12th lens.

[0151] The second lens group G2 is composed of, arranged in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, 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.

[0152] The third lens group G3 is composed of, arranged in order from the object side, a positive meniscus lens L31 with a convex surface facing the object side, and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during magnification. The positive meniscus lens L31 corresponds to the 31st lens, and its lens surface on the object side is aspheric. The positive lens L32 corresponds to the 32nd lens.

[0153] 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.

[0154] The fifth lens group G5 is composed of, arranged in order from the object side, a negative meniscus lens L51 with a concave surface facing the object side, and a biconvex positive lens L52.

[0155] 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.

[0156] The seventh lens group G7 is composed of, in order from the object side, a positive meniscus lens L71 with a concave surface facing the object side, a biconcave negative lens L72, and a negative meniscus lens L73 with a concave surface facing the object side. An image surface I is disposed on the image side of the seventh lens group G7. The lens surface of the negative lens L72 facing the object side is aspheric.

[0157] In this embodiment, the fifth lens group G5 and the sixth lens group G6 are moved independently toward the object side to focus from a long distance object to a close distance object (from an infinitely distant object to a finite distance object). That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

[0158] Table 7 below lists the values ​​of the specifications of the variable magnification optical system according to the seventh example.

[0159] (Table 7) [Overall specifications] Magnification ratio: 2.74 fRw=4055.914 WMT f 24.8 50.0 67.9 FNO 2.92 2.92 2.92 2ω 85.10 45.24 33.84 Ymax 21.60 21.60 21.60 TL 139.31 158.27 168.76 BF 11.75 23.48 28.76 [Lens specifications] Surface number RD nd νd Object plane ∞ 1 189.0188 2.500 1.84666 23.80 2 98.2637 5.200 1.75500 52.33 3 281.1360 0.200 4 58.7593 5.700 1.77250 49.62 5 135.0000 D5(variable) 6* 221.1138 2.000 1.74389 49.53 7 18.6091 9.662 8 -58.7660 1.300 1.77250 49.62 9 58.7660 0.506 10 39.8268 6.400 1.72825 28.38 11 -48.5880 1.773 12 -26.6513 1.300 1.61800 63.34 13 -70.7180 D13(variable) 14 ∞ 1.702 (Aperture S) 15* 71.3000 2.500 1.69370 53.32 16 121.5261 0.202 17 38.6117 5.900 1.59319 67.90 18 -111.3842 D18(variable) 19 66.4297 1.300 1.73800 32.33 20 19.7070 9.700 1.49782 82.57 21 -49.1811 D21(variable) 22 -23.7160 1.200 1.72047 34.71 23 -55.5303 0.200 24 103.5406 5.980 1.59349 67.00 25 -32.7186 D25(variable) 26 -75.1626 3.736 1.79189 45.04 27* -39.1303 D27(variable) 28 -44.6016 3.000 1.94594 17.98 29 -32.9994 0.201 30* -101.4301 1.500 1.85207 40.15 31 85.4850 7.927 32 -25.8904 1.400 1.58913 61.22 33 -45.0397 BF Image plane ∞ [Aspheric data] Page 6 κ=1.0000,A4=5.47971E-06,A6=-6.22095E-09 A8=1.44104E-11,A10=-2.08855E-14,A12=2.01910E-17 Page 15 κ=1.0000,A4=-4.50985E-06,A6=2.81159E-10 A8=-2.63745E-12,A10=-4.80538E-15,A12=0.00000E+00 Page 27 κ=1.0000,A4=1.09182E-05,A6=-2.25976E-08 A8=1.43325E-10,A10=-4.96895E-13,A12=6.77820E-16 Page 30 κ=1.0000,A4=-2.19229E-06,A6=-2.44256E-08 A8=6.38954E-11,A10=-1.65927E-13,A12=0.00000E+00 [Lens group data] Group starting plane focal length G1 1 118.121 G2 6 -21.898 G3 14 41.497 G4 19 109.585 G5 22 123.527 G6 26 98.560 G7 28 -47.807 [Variable interval data] W M T W M T Infinity Infinity Infinity Short distance Short distance Short distance D5 1.800 21.061 29.930 1.800 21.061 29.930 D13 19.119 6.127 2.000 19.119 6.127 2.000 D18 9.354 3.967 1.500 9.354 3.967 1.500 D21 5.286 14.229 18.845 4.337 12.953 17.517 D25 2.861 3.580 2.713 3.291 4.145 3.115 D27 6.143 2.841 2.028 6.662 3.552 2.955 [Conditional expression corresponding values] Conditional expression (1) f3 / f4 = 0.379 Conditional expression (2) dP1 / f1 = 0.065 Conditional expression (3) |fF| / ft = 1.819 Conditional expression (4) nN / nP = 1.160 Conditional expression (5) νN / νP = 0.392 Conditional expression (6) f1 / |fRw| = 0.029 Conditional expression (7) 2ωw = 85.10 Conditional expression (8) BFw / fw = 0.475 Conditional expression (9) (rR2 + rR1) / (rR2 - rR1) = 3.704

[0160] Fig. 20(A), Fig. 20(B), and Fig. 20(C) are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focusing on infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. Fig. 21(A), Fig. 21(C), and Fig. 21(C) are diagrams 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, the intermediate focal length state, and the telephoto end state, respectively. From each diagram of various aberrations, it can be seen that the variable magnification optical system according to Example 7 has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and further has excellent imaging performance when focusing on a close distance.

[0161] According to each embodiment, it is possible to realize high-speed and quiet autofocus without increasing the size of the lens barrel, and it is possible to realize a variable magnification optical system that suppresses fluctuations in aberration when changing magnification from the wide-angle end state to the telephoto end state, and when focusing from an object at infinity to an object at a close distance.

[0162] Here, the above-mentioned first to seventh examples show specific examples of this embodiment, and this embodiment is not limited to these.

[0163] The following contents can be appropriately adopted within a range that does not impair the optical performance of the variable magnification optical system according to this embodiment.

[0164] Although a 6-group configuration and a 7-group configuration have been shown as numerical examples of the variable magnification optical system, the present application is not limited to these, and a variable magnification optical system with other group configurations (e.g., 8 groups, etc.) can also be configured. Specifically, a lens or lens group can be added to the most object side or the most image side of the variable magnification optical system. 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.

[0165] 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.

[0166] 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.

[0167] The aperture diaphragm is preferably disposed between the second lens group and the third 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.

[0168] Each lens surface may be coated with an anti-reflection coating having a high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high-contrast optical performance. This reduces flare and ghosting and achieves high-contrast optical performance. [Explanation of symbols]

[0169] 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 I Image plane S Aperture stop

Claims

1. The optical system comprises, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a subsequent lens group, the subsequent lens group includes, in order from the object side, a fifth lens group, a sixth lens group, and a seventh lens group, During magnification change, the intervals between adjacent lens groups change, and the first lens group, the third lens group, and the fourth lens group move along the optical axis, When changing magnification from the wide-angle end state to the telephoto end state, the seventh lens group moves toward the object side along the optical axis, the subsequent lens group includes two focusing lens groups that move during focusing; the focusing lens group is composed of three or less single lenses, the first lens group includes, in order from the object side, a first lens having negative refractive power, a second lens having positive refractive power, and a third lens having positive refractive power; an aperture stop is disposed on the object side of the third lens group; A variable magnification optical system that satisfies the following condition: 0.353≦f3 / f4<2.10 0.010<dP1 / f1<0.075 where f3 is the focal length of the third lens group. f4: the focal length of the fourth lens group dP1: the sum of the center thickness of the first lens and the center thickness of the second lens f1: focal length of the first lens group

2. 2. The variable power optical system according to claim 1, wherein at least one of the focusing lens groups has a single lens having negative refractive power.

3. 3. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: 0.20<|fF| / ft<4.00 where fF is the focal length of the focusing lens group having the strongest refractive power among the focusing lens groups. ft: focal length of the variable magnification optical system in the telephoto end state

4. 4. The variable magnification optical system according to claim 1, which satisfies the following condition: f1 / |fRw|<5.00 where f1 is the focal length of the first lens group. fRw: focal length of the rear lens group in the wide-angle end state

5. 5. The variable magnification optical system according to claim 1, which satisfies the following condition: 2ωw>75° where ωw is the half angle of view of the variable magnification optical system in the wide-angle end state.

6. 6. The variable magnification optical system according to claim 1, which satisfies the following condition: 0.10<BFw / fw<1.00 where BFw is the back focus of the variable magnification optical system in the wide-angle end state. fw: focal length of the variable magnification optical system in the wide-angle end state

7. 7. The variable magnification optical system according to claim 1, wherein the following condition is satisfied when the focusing lens group has a positive refractive power: 1 / 2<1 / 2 ... 0.00<(rR2+rR1) / (rR2-rR1)<8.00 where rR1 is the radius of curvature of the object-side lens surface of the lens arranged closest to the image side of the variable magnification optical system. rR2: the radius of curvature of the image-side lens surface of the lens arranged closest to the image side of the variable magnification optical system

8. 7. The variable magnification optical system according to claim 1, wherein the following condition is satisfied when the focusing lens group has negative refractive power: 1 / 2<1 / 2<1 / 2 . -4.00<(rR2+rR1) / (rR2-rR1)<4.00 where rR1 is the radius of curvature of the object-side lens surface of the lens arranged closest to the image side of the variable magnification optical system. rR2: the radius of curvature of the image-side lens surface of the lens arranged closest to the image side of the variable magnification optical system

9. 9. An optical instrument comprising the variable magnification optical system according to claim 1.

Images