Variable magnification optical systems and optical instruments

Abstract

To provide a compact, bright, and highly optically efficient variable magnification optical system. [Solution] The variable magnification optical system ZL consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a rear group GR having at least five lens groups, all arranged in order from the object side along the optical axis. When magnification changes from the wide-angle end state W to the first telephoto end state T1, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and the second lens group moves along the optical axis. When magnification changes from the first telephoto end state T1 to the second telephoto end state T2, the first and second lens groups are fixed with respect to the image plane, and at least two of the at least five lens groups in the rear group move along the optical axis, satisfying the following condition. 0.75 <MG2 / (-f2)<1.30 ft1 / ft2 < 0.95

Description

[Technical Field]

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

[0002] Conventionally, variable magnification optical systems suitable for photographic cameras, electronic still cameras, video cameras, etc., have been proposed (see, for example, Patent Document 1). However, it is difficult to achieve bright and good optical performance while keeping such variable magnification optical systems compact. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-52338 [Overview of the project]

[0004] The first variable magnification optical system according to the present invention consists of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, arranged in order from the object side along the optical axis. When magnification changes from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and N1 lens groups move along the optical axis. When magnification changes from the first telephoto end state to the second telephoto end state, the first lens group is fixed with respect to the image plane, and N2 lens groups move along the optical axis, where N1 is an integer of 3 or more, and N2 is a positive integer less than N1, and satisfies the following conditional expression. 0.10 <MB / MA<2.00 ft1 / ft2 < 0.95 However, MA: The amount of movement of the lens group with the largest movement when changing magnification from the wide-angle end to the first telephoto end. MB: The amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state. ft1: Focal length of the variable magnification optical system in the first telephoto end state. ft2: Focal length of the variable magnification optical system in the second telephoto end state.

[0005] The second variable magnification optical system according to the present invention comprises a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, arranged in order from the object side along the optical axis. When magnification changes from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and the second lens group moves along the optical axis. When magnification changes from the first telephoto end state to the second telephoto end state, the first lens group and the second lens group are fixed with respect to the image plane, and at least a part of the rear group moves along the optical axis, satisfying the following conditional equation. 0.75 <MG2 / (-f2)<1.30 ft1 / ft2 < 0.95 However, f2: focal length of the second lens group MG2: Amount of movement of the second lens group when changing magnification from the wide-angle end to the first telephoto end. ft1: Focal length of the variable magnification optical system in the first telephoto end state. ft2: Focal length of the variable magnification optical system in the second telephoto end state.

[0006] The optical instrument according to the present invention is configured to include the above-mentioned variable magnification optical system.

[0007] The first method for manufacturing a variable magnification optical system according to the present invention is a method for manufacturing a variable magnification optical system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, arranged in order from the object side along the optical axis, wherein when magnification is changed from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and N1 lens groups move along the optical axis, and when magnification is changed from the first telephoto end state to the second telephoto end state, the first lens group is fixed with respect to the image plane, and N2 lens groups move along the optical axis, where N1 is an integer of 3 or more, and N2 is a positive integer less than N1, and the following condition is satisfied, and the lenses are arranged in the lens barrel. 0.10 <MB / MA<2.00 ft1 / ft2 < 0.95 However, MA: The amount of movement of the lens group with the largest movement when changing magnification from the wide-angle end to the first telephoto end. MB: The amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state. ft1: Focal length of the variable magnification optical system in the first telephoto end state. ft2: Focal length of the variable magnification optical system in the second telephoto end state.

[0008] A second method for manufacturing a variable magnification optical system according to the present invention is a method for manufacturing a variable magnification optical system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, arranged in order from the object side along the optical axis, wherein when magnification is changed from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and the second lens group moves along the optical axis, and when magnification is changed from the first telephoto end state to the second telephoto end state, the first lens group and the second lens group are fixed with respect to the image plane, and at least a part of the rear group moves along the optical axis, and the lenses are arranged in the lens barrel such that the following condition is satisfied. 0.75 <MG2 / (-f2)<1.30 ft1 / ft2 < 0.95 However, f2: focal length of the second lens group MG2: Amount of movement of the second lens group when changing magnification from the wide-angle end to the first telephoto end. ft1: Focal length of the variable magnification optical system in the first telephoto end state. ft2: Focal length of the variable magnification optical system in the second telephoto end state.

[0009] The optical system according to the third invention includes a zoom lens group that moves in the optical axis direction when zooming from the wide-angle end state to the first telephoto end state, and a focusing lens group that moves in the optical axis direction when zooming from the wide-angle end state to the first telephoto end state and also moves in the optical axis direction for focusing. The zoom lens group remains fixed in the optical axis direction, and the focusing lens group is moved in the optical axis direction to switch from the first telephoto state to a second telephoto state with a higher magnification.

Brief Description of the Drawings

[0010] [Figure 1] It is a diagram showing the lens configuration of the zoom optical system according to the first embodiment. [Figure 2] It is a schematic diagram showing the lens position control mechanism according to the first embodiment. [Figure 3] It is a diagram of various aberrations at infinity focus in the wide-angle end state of the zoom optical system according to the first embodiment. [Figure 4] It is a diagram of various aberrations at infinity focus in the first telephoto end state of the zoom optical system according to the first embodiment. [Figure 5] It is a diagram of various aberrations at infinity focus in the second telephoto end state of the zoom optical system according to the first embodiment. [Figure 6] It is a diagram showing the lens configuration of the zoom optical system according to the second embodiment. [Figure 7] It is a schematic diagram showing the lens position control mechanism according to the second embodiment. [Figure 8] It is a diagram of various aberrations at infinity focus in the wide-angle end state of the zoom optical system according to the second embodiment. [Figure 9] It is a diagram of various aberrations at infinity focus in the first telephoto end state of the zoom optical system according to the second embodiment. [Figure 10] It is a diagram of various aberrations at infinity focus in the second telephoto end state of the zoom optical system according to the second embodiment. [Figure 11] It is a diagram showing the lens configuration of the zoom optical system according to the third embodiment. [Figure 12] It is a schematic diagram showing the lens position control mechanism according to the third embodiment. [Figure 13]This is a diagram of aberrations when the variable magnification optical system according to the third embodiment is in focus at infinity at the wide-angle end. [Figure 14] This is a diagram of aberrations when the variable magnification optical system according to the third embodiment is in focus at infinity in the first telephoto end state. [Figure 15] This is a diagram of aberrations when the variable magnification optical system according to the third embodiment is in focus at infinity in the second telephoto end state. [Figure 16] This figure shows the configuration of a camera equipped with a variable magnification optical system according to each embodiment. [Figure 17] This flowchart shows a method for manufacturing a variable magnification optical system according to the first embodiment. [Figure 18] This is a flowchart showing a method for manufacturing a variable magnification optical system according to the second embodiment. [Modes for carrying out the invention]

[0011] The following describes preferred embodiments of the present invention. First, a camera (optical device) equipped with a variable magnification optical system according to each embodiment will be described with reference to Figure 16. As shown in Figure 16, this camera 1 consists of a main body 2 and a shooting lens 3 attached to the main body 2. The main body 2 includes an image sensor 4, a main body control unit (not shown) that controls the operation of the digital camera, and a liquid crystal screen 5. The shooting lens 3 includes a variable magnification optical system ZL consisting of a plurality of lens groups and a lens position control mechanism (not shown) that controls the position of each lens group.

[0012] Light from the subject is focused by the variable magnification optical system ZL of the photographic lens 3 and reaches the image plane I of the image sensor 4. The light from the subject that reaches the image plane I is photoelectrically converted by the image sensor 4 and recorded as digital image data in memory (not shown). The digital image data recorded in memory can be displayed on the liquid crystal screen 5 according to the user's operation. This camera may be a mirrorless camera or a single-lens reflex type camera with a quick-return mirror. Also, the variable magnification optical system ZL shown in Figure 16 is a schematic representation of a variable magnification optical system provided in the photographic lens 3, and the lens configuration of the variable magnification optical system ZL is not limited to this configuration.

[0013] Next, a variable magnification optical system according to the first embodiment will be described. As an example of a variable magnification optical system (zoom lens) ZL according to the first embodiment, the variable magnification optical system ZL(1) consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a rear group GR having at least five lens groups, all arranged in order from the object side along the optical axis, as shown in Figure 1. When magnification changes from the wide-angle end state (W) to the first telephoto end state (T1), the spacing between adjacent lens groups changes, the first lens group G1 is fixed with respect to the image plane I, and N1 lens groups move along the optical axis. When magnification changes from the first telephoto end state (T1) to the second telephoto end state (T2), the first lens group G1 is fixed with respect to the image plane I, and N2 lens groups move along the optical axis. Here, N1 is an integer of 3 or more, and N2 is a positive integer less than N1.

[0014] Under the above configuration, the variable magnification optical system ZL according to the first embodiment satisfies the following conditions (1) and (2). 0.10 <MB / MA<2.00 ···(1) ft1 / ft2 < 0.95 ···(2) However, MA: The amount of movement of the lens group with the largest movement when changing magnification from the wide-angle end to the first telephoto end. MB: The amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state. ft1: Focal length of the variable magnification optical system ZL at the first telephoto end state ft2: Focal length of the variable magnification optical system ZL at the second telephoto end.

[0015] According to the first embodiment, it is possible to obtain a variable magnification optical system that is compact yet bright and has good optical performance, and an optical instrument equipped with this variable magnification optical system. The magnification ratio (magnification) in the second telephoto state is greater than that in the first telephoto state. That is, by switching from the first telephoto state to the second telephoto state, the magnification can be increased. This provides an effect similar to that of using a teleconverter in a so-called interchangeable lens camera. This is also true in the second and third embodiments.

[0016] The scaling from the wide-angle end (W) through the intermediate focal length (M) to the first telephoto end (T1) continuously changes the focal length of the entire optical system while maintaining image formation on the same plane. In other words, the scaling is controlled so that the focal length is appropriate for each state from the wide-angle end (W) to the first telephoto end (T1). On the other hand, the scaling (switching) from the first telephoto end (T1) to the second telephoto end (T2) does not require a continuous change in focal length; it is sufficient that the image is in focus and formed at least at the first telephoto end (T1) and the second telephoto end (T2), and imaging performance in between is not required. This is similar to attaching and detaching a teleconverter in a so-called interchangeable lens camera, where attaching a teleconverter from the first telephoto end (T1) results in the second telephoto end (T2). Therefore, the magnification from the first telephoto end state (T1) to the second telephoto end state (T2) does not require continuous control like the magnification from the wide-angle end state (W) to the first telephoto end state (T1), and may be intermittent (discrete). As can be seen from the above description, according to the first embodiment, the focal length can be increased from the first telephoto end state (T1) to the second telephoto end state (T2) with the same optical system and without the need to attach a teleconverter. These points are not limited to the magnification optical system ZL according to the first embodiment, but are also true for the magnification optical system according to the second embodiment. Furthermore, the same applies to the magnification optical system ZL(1) as the first embodiment shown in Figure 1, the magnification optical system ZL(2) as the second embodiment shown in Figure 6, and the magnification optical system ZL(3) as the third embodiment shown in Figure 11.

[0017] Conditional equation (1) defines an appropriate relationship between the amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state, and the amount of movement of the lens group with the largest movement when changing magnification from the wide-angle end state to the first telephoto end state. In each embodiment, the amount of movement of the lens group when changing magnification from the wide-angle end state to the first telephoto end state represents the difference (absolute value) between the position of the lens group on the optical axis in the first telephoto end state and the position of the lens group on the optical axis in the wide-angle end state. The amount of movement of the lens group when changing magnification from the first telephoto end state to the second telephoto end state represents the difference (absolute value) between the position of the lens group on the optical axis in the second telephoto end state and the position of the lens group on the optical axis in the first telephoto end state. By satisfying conditional equation (1), spherical aberration, coma aberration, and field curvature can be corrected well.

[0018] If the corresponding value in conditional equation (1) exceeds the upper limit, the amount of movement of the lens group with the largest movement during the magnification change from the wide-angle end state to the first telephoto end state becomes smaller, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in that lens group. By setting the upper limit of conditional equation (1) to 1.75, 1.50, 1.25, 1.00, 0.80, 0.65, and further to 0.50, the effect of the first embodiment can be made more reliable.

[0019] If the corresponding value in conditional equation (1) falls below the lower limit, the amount of movement of the lens group with the largest movement during the magnification change from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in that lens group. By setting the lower limit of conditional equation (1) to 0.10, 0.20, 0.30, and further to 0.40, the effect of the first embodiment can be made more reliable.

[0020] Conditional equation (2) defines an appropriate relationship between the focal length of the variable magnification optical system ZL in the first telephoto end state and the focal length of the variable magnification optical system ZL in the second telephoto end state. By satisfying conditional equation (2), it becomes possible to obtain a variable magnification optical system that is compact yet has a high magnification ratio. By setting the upper limit of conditional equation (2) to 0.90, 0.85, 0.80, and further to 0.75, the effect of the first embodiment can be made more reliable. Furthermore, by setting the lower limit of conditional equation (2) to 0.45, 0.50, and further to 0.60, the effect of the first embodiment can be made more reliable.

[0021] In the variable magnification optical system ZL according to the first embodiment, the rear group GR includes N2 focusing lens groups that move along the optical axis when focusing, and the N2 focusing lens groups may move along the optical axis when magnification changes from the first telephoto end state to the second telephoto end state. Here, N2 is an integer of 2 or more that is less than N1. This makes it possible to obtain a variable magnification optical system that is compact yet has a high magnification ratio. The lens group that moves when focusing in the wide-angle end state may be called the focusing lens group.

[0022] Next, a variable magnification optical system according to the second embodiment will be described. The variable magnification optical system ZL according to the second embodiment has the same configuration as the variable magnification optical system ZL according to the first embodiment, and will be described using the same reference numerals as in the first embodiment. As an example of the variable magnification optical system (zoom lens) ZL according to the second embodiment, the variable magnification optical system ZL(1) consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a rear group GR, which are arranged in order from the object side along the optical axis, as shown in Figure 1. When magnification occurs from the wide-angle end state (W) to the first telephoto end state (T1), the spacing between adjacent lens groups changes, the first lens group G1 is fixed with respect to the image plane I, and the second lens group G2 moves along the optical axis. When changing magnification from the first telephoto end state (T1) to the second telephoto end state (T2), the first lens group G1 and the second lens group G2 are fixed with respect to the image plane I, and at least a part of the rear group GR moves along the optical axis.

[0023] Under the above configuration, the variable magnification optical system ZL according to the second embodiment satisfies the following conditions (3) and (2). 0.75 <MG2 / (-f2)<1.30 ···(3) ft1 / ft2 < 0.95 ···(2) However, f2: Focal length of the second lens group G2 MG2: The amount of movement of the second lens group G2 when changing magnification from the wide-angle end to the first telephoto end. ft1: Focal length of the variable magnification optical system ZL at the first telephoto end state ft2: Focal length of the variable magnification optical system ZL at the second telephoto end.

[0024] According to the second embodiment, it becomes possible to obtain a variable magnification optical system that is compact yet bright and has good optical performance, and an optical instrument equipped with this variable magnification optical system.

[0025] Similar to the first embodiment, the magnification from the wide-angle end state (W) through the intermediate focal length state (M) to the first telephoto end state (T1) is controlled so that the focal length is appropriate for any state from the wide-angle end state (W) to the first telephoto end state (T1). On the other hand, the magnification (switching) from the first telephoto end state (T1) to the second telephoto end state (T2) is similar to attaching and detaching a teleconverter in a so-called interchangeable lens camera, and does not require continuous control like the magnification from the wide-angle end state (W) to the first telephoto end state (T1), and may be intermittent (discrete). In the second embodiment as well, the focal length can be increased from the first telephoto end state (T1) to the second telephoto end state (T2) with the same optical system and without the need to attach a teleconverter.

[0026] Conditional equation (3) defines the appropriate relationship between the amount of movement of the second lens group G2 when changing magnification from the wide-angle end to the first telephoto end, and the focal length of the second lens group G2. By satisfying conditional equation (3), spherical aberration, coma aberration, and field curvature can be corrected well.

[0027] If the corresponding value in conditional equation (3) exceeds the upper limit, the refractive power of the second lens group G2 becomes stronger, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the second lens group G2. By setting the upper limit of conditional equation (3) to 1.20, and further to 1.10, the effect of the second embodiment can be made more reliable.

[0028] If the corresponding value in conditional equation (3) falls below the lower limit, the amount of movement of the second lens group G2 during magnification from the wide-angle end to the first telephoto end becomes small, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the second lens group G2. By setting the lower limit of conditional equation (3) to 0.80, and further to 0.85, the effect of the second embodiment can be made more reliable.

[0029] As mentioned above, condition (2) defines an appropriate relationship between the focal length of the variable magnification optical system ZL in the first telephoto end state and the focal length of the variable magnification optical system ZL in the second telephoto end state. By satisfying condition (2), it becomes possible to obtain a variable magnification optical system that is compact yet has a high magnification ratio. By setting the upper limit of condition (2) to 0.90, 0.85, 0.80, and further to 0.75, the effect of the second embodiment can be made more certain. Also, by setting the lower limit of condition (2) to 0.45, 0.50, and further to 0.60, the effect of the second embodiment can be made more certain.

[0030] In the variable magnification optical system ZL according to the second embodiment, the rear group GR includes at least two focusing lens groups that move along the optical axis when focusing, and these at least two focusing lens groups may move along the optical axis when changing magnification from the first telephoto end state to the second telephoto end state. This makes it possible to obtain a variable magnification optical system that is compact yet has a high magnification ratio. The lens group that moves when focusing in the wide-angle end state may be referred to as the focusing lens group.

[0031] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (4). 0.01 <Bft2 / ft2<0.30 ···(4) However, Bft2: The back focus of the variable magnification optical system ZL in the second telephoto end state.

[0032] Conditional equation (4) defines an appropriate relationship between the back focus of the variable magnification optical system ZL in the second telephoto end state and the focal length of the variable magnification optical system ZL in the second telephoto end state. By satisfying conditional equation (4), it is possible to obtain a variable magnification optical system that is compact, bright, and has good optical performance. By setting the upper limit of conditional equation (4) to 0.20, 0.15, 0.10, and further to 0.06, the effects of each embodiment can be made more reliable. Furthermore, by setting the lower limit of conditional equation (4) to 0.02, and further to 0.04, the effects of each embodiment can be made more reliable.

[0033] In the variable magnification optical system ZL according to the first and second embodiments, the rear group GR includes the final lens group GE, which is positioned closest to the image plane. The final lens group GE may be fixed relative to the image plane I during magnification from the wide-angle end to the first telephoto end and from the first telephoto end to the second telephoto end. This allows the variable magnification optical system to be made more compact.

[0034] Furthermore, in the variable magnification optical system ZL according to the first and second embodiments, the third lens group G3 may be fixed with respect to the image plane I when changing magnification from the first telephoto end state to the second telephoto end state.

[0035] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (5). 0.75 <D23 / (-f2)<1.40 ···(5) However, f2: Focal length of the second lens group G2 D23: The amount of change in the distance between the second lens group G2 and the third lens group G3 on the optical axis when changing magnification from the wide-angle end to the first telephoto end.

[0036] Conditional equation (5) defines an appropriate relationship between the change in the distance between the second lens group G2 and the third lens group G3 on the optical axis when changing magnification from the wide-angle end state to the first telephoto end state, and the focal length of the second lens group G2. In each embodiment, the change in the distance between the second lens group G2 and the third lens group G3 on the optical axis when changing magnification from the wide-angle end state to the first telephoto end state represents the difference (absolute value) between the distance between the second lens group G2 and the third lens group G3 on the optical axis in the first telephoto end state and the distance between the second lens group G2 and the third lens group G3 on the optical axis in the wide-angle end state. By satisfying conditional equation (5), spherical aberration and coma aberration can be corrected well.

[0037] If the corresponding value in conditional equation (5) exceeds the upper limit, the refractive power of the second lens group G2 becomes stronger, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the second lens group G2. By setting the upper limit of conditional equation (5) to 1.30, and further to 1.25, the effects of each embodiment can be made more reliable.

[0038] If the corresponding value in conditional equation (5) falls below the lower limit, the amount of change in the distance between the second lens group G2 and the third lens group G3 on the optical axis during magnification from the wide-angle end to the first telephoto end becomes small, requiring a stronger refractive power of the second lens group G2, making it difficult to correct spherical aberration and coma aberration. By setting the lower limit of conditional equation (5) to 0.80, and further to 0.85, the effects of each embodiment can be made more reliable.

[0039] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (6). 0.45 <D23 / f3<1.00 ···(6) However, f3: Focal length of the third lens group G3 D23: The amount of change in the distance between the second lens group G2 and the third lens group G3 on the optical axis when changing magnification from the wide-angle end to the first telephoto end.

[0040] Conditional equation (6) defines the appropriate relationship between the change in the distance between the second lens group G2 and the third lens group G3 on the optical axis when changing magnification from the wide-angle end to the first telephoto end, and the focal length of the third lens group G3. By satisfying conditional equation (6), spherical aberration and coma aberration can be corrected well.

[0041] If the corresponding value in conditional equation (6) exceeds the upper limit, the refractive power of the third lens group G3 becomes stronger, making it difficult to correct the spherical aberration and coma aberration occurring in the third lens group G3. By setting the upper limit of conditional equation (6) to 0.90, and further to 0.85, the effects of each embodiment can be made more reliable.

[0042] If the corresponding value in conditional equation (6) falls below the lower limit, the change in the distance between the second lens group G2 and the third lens group G3 on the optical axis during magnification from the wide-angle end to the first telephoto end becomes small, requiring a stronger refractive power of the second lens group G2, making it difficult to correct spherical aberration and coma aberration. By setting the lower limit of conditional equation (6) to 0.50, and further to 0.60, the effects of each embodiment can be made more reliable.

[0043] In the variable magnification optical system ZL according to the first and second embodiments, the rear group GR may include at least two focusing lens groups that move along the optical axis when focusing, and may satisfy the following condition (7). 0 <MF1w / MF1t<1.00 ···(7) However, MF1w: The amount of movement of the first focusing lens group GF1, which is positioned closest to the object among the at least two focusing lens groups, when changing magnification from the wide-angle end state to the first telephoto end state. MF1t: The amount of movement of the first focusing lens group GF1 when changing magnification from the first telephoto end state to the second telephoto end state.

[0044] Conditional equation (7) defines an appropriate relationship between the amount of movement of the first focusing lens group GF1 when changing magnification from the wide-angle end state to the first telephoto end state, and the amount of movement of the first focusing lens group GF1 when changing magnification from the first telephoto end state to the second telephoto end state. By satisfying conditional equation (7), spherical aberration and field curvature can be corrected well.

[0045] If the corresponding value in conditional equation (7) exceeds the upper limit, the amount of movement of the first focusing lens group GF1 during magnification from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct spherical aberration and field curvature occurring in the first focusing lens group GF1. By setting the upper limit of conditional equation (7) to 0.80, and further to 0.60, the effects of each embodiment can be made more reliable.

[0046] If the corresponding value in conditional equation (7) falls below the lower limit, the amount of movement of the first focusing lens group GF1 during magnification from the wide-angle end to the first telephoto end becomes small, making it difficult to correct spherical aberration and field curvature occurring in the first focusing lens group GF1. By setting the lower limit of conditional equation (7) to 0.002, 0.10, and further to 0.20, the effects of each embodiment can be made more reliable.

[0047] In the variable magnification optical system ZL according to the first and second embodiments, the rear group GR may include at least two focusing lens groups that move along the optical axis when focusing, and may satisfy the following condition (8). 0.05 <MF2w / MF2t<10.00 ···(8) However, MF2w: The amount of movement of the second focusing lens group GF2, which is the second lens group from the object side among the at least two focusing lens groups, when changing magnification from the wide-angle end state to the first telephoto end state. MF2t: The amount of movement of the second focusing lens group GF2 when changing magnification from the first telephoto end state to the second telephoto end state.

[0048] Conditional equation (8) defines an appropriate relationship between the amount of movement of the second focusing lens group GF2 when changing magnification from the wide-angle end state to the first telephoto end state, and the amount of movement of the second focusing lens group GF2 when changing magnification from the first telephoto end state to the second telephoto end state. By satisfying conditional equation (8), spherical aberration and field curvature can be corrected well.

[0049] If the corresponding value in conditional equation (8) exceeds the upper limit, the amount of movement of the second focusing lens group GF2 during magnification from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct spherical aberration and field curvature occurring in the second focusing lens group GF2. By setting the upper limit of conditional equation (8) to 8.00, and further to 6.00, the effects of each embodiment can be made more reliable.

[0050] If the corresponding value in conditional equation (8) falls below the lower limit, the amount of movement of the second focusing lens group GF2 during magnification from the wide-angle end to the first telephoto end becomes small, making it difficult to correct spherical aberration and field curvature occurring in the second focusing lens group GF2. By setting the lower limit of conditional equation (8) to 0.10, and further to 0.20, the effects of each embodiment can be made more reliable.

[0051] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (9). 0.01 <MC / MB<2.00 ···(9) However, MB: The amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state. MC: The amount of movement of the lens group with the smallest movement when changing magnification from the first telephoto end state to the second telephoto end state.

[0052] Conditional equation (9) defines an appropriate relationship between the amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state, and the amount of movement of the lens group with the smallest movement when changing magnification from the first telephoto end state to the second telephoto end state. By satisfying conditional equation (9), spherical aberration, coma aberration, and field curvature can be corrected well.

[0053] If the corresponding value in conditional equation (9) exceeds the upper limit, the amount of movement of the lens group with the largest movement during the magnification change from the first telephoto end state to the second telephoto end state becomes smaller, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in that lens group. By setting the upper limit of conditional equation (9) to 1.20, 1.10, 1.00, 0.85, and further to 0.75, the effects of each embodiment can be made more reliable.

[0054] If the corresponding value in conditional equation (9) falls below the lower limit, the amount of movement of the lens group with the smallest movement during the magnification change from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct the spherical aberration, coma aberration, and field curvature occurring in that lens group. By setting the lower limit of conditional equation (9) to 0.03, and further to 0.05, the effects of each embodiment can be made more reliable.

[0055] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (10). 0.10 <Bft2 / MB<5.00 ···(10) However, MB: The amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state. Bft2: Back focus of the variable magnification optical system ZL at the second telephoto end.

[0056] Conditional equation (10) defines an appropriate relationship between the back focus of the variable magnification optical system ZL in the second telephoto end state and the amount of movement of the lens group with the largest movement during magnification from the first telephoto end state to the second telephoto end state. By satisfying conditional equation (10), it is possible to obtain a variable magnification optical system that is compact, bright, and has good optical performance. By setting the upper limit of conditional equation (10) to 3.00 and further to 1.20, the effects of each embodiment can be made more reliable. Furthermore, by setting the lower limit of conditional equation (10) to 0.30 and further to 0.60, the effects of each embodiment can be made more reliable.

[0057] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (11). 0.05 < (-f2) / f1 < 1.00 ... (11) However, f1: Focal length of the first lens group G1 f2: Focal length of the second lens group G2

[0058] Conditional equation (11) defines the appropriate relationship between the focal length of the second lens group G2 and the focal length of the first lens group G1. By satisfying conditional equation (11), spherical aberration, coma aberration, and field curvature can be effectively corrected.

[0059] If the corresponding value in conditional equation (11) exceeds the upper limit, the refractive power of the first lens group G1 becomes stronger, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the first lens group G1. By setting the upper limit of conditional equation (11) to 0.80, 0.70, 0.50, 0.40, and further to 0.37, the effects of each embodiment can be made more reliable.

[0060] If the corresponding value in conditional equation (11) falls below the lower limit, the refractive power of the second lens group G2 increases, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the second lens group G2. By setting the lower limit of conditional equation (11) to 0.10, 0.15, 0.20, 0.25, and further to 0.30, the effects of each embodiment can be made more reliable.

[0061] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (12). 0.01 <Bfw / fw<0.50 ···(12) However, fw: focal length of the variable magnification optical system ZL at the wide-angle end. Bfw: Back focus of the variable magnification optical system ZL at the wide-angle end.

[0062] Conditional equation (12) defines an appropriate relationship between the back focus of the variable magnification optical system ZL at the wide-angle end and the focal length of the variable magnification optical system ZL at the wide-angle end. By satisfying conditional equation (12), it is possible to obtain a variable magnification optical system that is compact, bright, and has good optical performance. By setting the upper limit of conditional equation (12) to 0.45, 0.40, 0.35, 0.33, 0.30, and further to 0.28, the effects of each embodiment can be made more reliable. Furthermore, by setting the lower limit of conditional equation (12) to 0.05, 0.10, and further to 0.13, the effects of each embodiment can be made more reliable.

[0063] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (13). 2.00 <TLw / fw<6.00 ···(13) However, fw: focal length of the variable magnification optical system ZL at the wide-angle end. TLw: Total length of the variable magnification optical system ZL at the wide-angle end.

[0064] Conditional equation (13) defines an appropriate relationship between the total length of the variable magnification optical system ZL at the wide-angle end and the focal length of the variable magnification optical system ZL at the wide-angle end. By satisfying conditional equation (13), it is possible to obtain a variable magnification optical system that is compact, bright, and has good optical performance. By setting the upper limit of conditional equation (13) to 5.50, 5.00, 4.50, and further to 4.00, the effects of each embodiment can be made more reliable. Furthermore, by setting the lower limit of conditional equation (13) to 2.50, 2.80, 3.00, and further to 3.10, the effects of each embodiment can be made more reliable.

[0065] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (14). 0.01 < (-f2) / f3 < 2.00 ···(14) However, f2: Focal length of the second lens group G2 f3: Focal length of the third lens group G3

[0066] Conditional equation (14) defines the appropriate relationship between the focal length of the second lens group G2 and the focal length of the third lens group G3. By satisfying conditional equation (14), spherical aberration, coma aberration, and field curvature can be effectively corrected.

[0067] If the corresponding value in conditional equation (14) exceeds the upper limit, the refractive power of the third lens group G3 increases, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the third lens group G3. By setting the upper limit of conditional equation (14) to 1.80, 1.60, 1.50, 1.35, 1.10, and further to 1.00, the effects of this embodiment can be made more reliable.

[0068] If the corresponding value in conditional equation (14) falls below the lower limit, the refractive power of the second lens group G2 increases, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the second lens group G2. By setting the lower limit of conditional equation (14) to 0.10, 0.20, 0.30, 0.35, 0.45, 0.50, and further to 0.55, the effects of this embodiment can be made more reliable.

[0069] The variable magnification optical system ZL according to the first and second embodiments may satisfy the following condition (15). 1.80 <f1 / f3<2.50 ···(15) However, f1: Focal length of the first lens group G1 f3: Focal length of the third lens group G3

[0070] Conditional equation (15) defines the appropriate relationship between the focal length of the first lens group G1 and the focal length of the third lens group G3. By satisfying conditional equation (15), spherical aberration, coma aberration, and field curvature can be effectively corrected.

[0071] If the corresponding value in conditional equation (15) exceeds the upper limit, the refractive power of the third lens group G3 increases, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the third lens group G3. By setting the upper limit of conditional equation (15) to 2.45, 2.40, and further to 2.35, the effects of this embodiment can be made more reliable.

[0072] If the corresponding value in conditional equation (15) falls below the lower limit, the refractive power of the first lens group G1 increases, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the first lens group G1. By setting the lower limit of conditional equation (15) to 1.85, and further to 1.90, the effects of this embodiment can be made more reliable.

[0073] In the variable magnification optical system ZL according to the first and second embodiments, the rear group GR may include the final lens group GE located closest to the image plane, and may satisfy the following condition (16). 0.01 < |fr1 / fr| < 5.00 ···(16) However, fr: focal length of the final lens group GE fr1: The focal length of the lens group in the rear group GR that is positioned next to the object side of the final lens group GE.

[0074] Condition (16) defines an appropriate relationship between the focal lengths of the lens groups arranged in the rear group GR alongside the object side of the final lens group GE, and the focal length of the final lens group GE. By satisfying condition (16), field curvature can be corrected effectively.

[0075] If the corresponding value in conditional equation (16) exceeds the upper limit, the refractive power of the final lens group GE becomes stronger, making it difficult to correct the field curvature occurring in the final lens group GE. By setting the upper limit of conditional equation (16) to 4.80, 4.50, 4.30, 3.50, 3.30, 3.00, 2.80, and further to 2.50, the effect of this embodiment can be made more reliable.

[0076] If the corresponding value in conditional equation (16) falls below the lower limit, the refractive power of the lens group arranged in the rear group GR alongside the object side of the final lens group GE becomes stronger, making it difficult to correct the coma aberration and field curvature occurring in the lens group arranged in the object side of the final lens group GE. By setting the lower limit of conditional equation (16) to 0.10, 0.20, 0.25, 0.35, 0.45, and further to 0.50, the effect of this embodiment can be made more reliable.

[0077] In the variable magnification optical system ZL according to the first and second embodiments, the rear group GR may include the final lens group GE, which is positioned closest to the image plane, and may satisfy the following condition (17). 0.10 <f2 / fr1<0.75 ···(17) However, f2: Focal length of the second lens group G2 fr1: The focal length of the lens group in the rear group GR that is positioned next to the object side of the final lens group GE.

[0078] Conditional equation (17) defines the appropriate relationship between the focal length of the second lens group G2 and the focal length of the lens group arranged in the rear group GR, adjacent to the object side of the final lens group GE. By satisfying conditional equation (17), coma aberration and field curvature can be effectively corrected.

[0079] If the corresponding value in conditional equation (17) exceeds the upper limit, the refractive power of the lens group arranged in line with the object side of the final lens group GE in the rear group GR becomes stronger, making it difficult to correct the coma aberration and field curvature occurring in the lens group arranged in line with the object side of the final lens group GE. By setting the upper limit of conditional equation (17) to 0.70, and further to 0.68, the effect of this embodiment can be made more reliable.

[0080] If the corresponding value in conditional equation (17) falls below the lower limit, the refractive power of the second lens group G2 increases, making it difficult to correct spherical aberration, coma aberration, and field curvature occurring in the second lens group G2. By setting the lower limit of conditional equation (17) to 0.15, and further to 0.20, the effects of this embodiment can be made more reliable.

[0081] Next, with reference to Figure 17, the manufacturing method of the variable magnification optical system ZL according to the first embodiment will be outlined. First, along the optical axis, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a rear group GR are arranged in order (step ST1). Next, when magnification changes from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group G1 is fixed with respect to the image plane I, and N1 lens groups are configured to move along the optical axis (step ST2). Also, when magnification changes from the first telephoto end state to the second telephoto end state, the first lens group G1 is fixed with respect to the image plane I, and N2 lens groups are configured to move along the optical axis (step ST3). As mentioned above, N1 is an integer of 3 or more, and N2 is a positive integer less than N1. Then, each lens is arranged in the lens barrel such that at least conditions (1) and (2) above are satisfied (step ST4). This manufacturing method makes it possible to manufacture a variable magnification optical system that is small, yet bright and has good optical performance.

[0082] Next, with reference to Figure 18, the manufacturing method of the variable magnification optical system ZL according to the second embodiment will be outlined. First, along the optical axis, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a rear group GR are arranged (step ST11). Next, when magnification is changed from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group G1 is fixed with respect to the image plane I, and the second lens group G2 moves along the optical axis (step ST12). Also, when magnification is changed from the first telephoto end state to the second telephoto end state, the first lens group G1 and the second lens group G2 are fixed with respect to the image plane I, and at least a part of the rear group GR moves along the optical axis (step ST13). Then, each lens is arranged in the lens barrel so as to satisfy at least the above conditions (3) and (2) (step ST14). This manufacturing method makes it possible to produce a variable magnification optical system that is compact yet bright and has good optical performance. [Examples]

[0083] The following describes the variable magnification optical system ZL according to the embodiments of each example, based on the drawings. Figures 1, 6, and 11 are cross-sectional views showing the configuration and refractive power distribution of the variable magnification optical system ZL{ZL(1) to ZL(3)} according to the first to third embodiments. In the cross-sectional views of the variable magnification optical systems ZL(1) to ZL(3) according to the first to third embodiments, the direction of movement of each lens group when magnifying from the wide-angle end state (W) through the intermediate focal state (M) to the first telephoto end state (T1), and when magnifying from the first telephoto end state (T1) to the second telephoto end state (T2), are indicated by arrows. In addition, the direction of movement of the focusing lens group when focusing from infinity to a close-range object is indicated by an arrow along with the word "Focused".

[0084] In Figures 1, 6, and 11, each lens group is represented by a combination of code G and a number, and each lens is represented by a combination of code L and a number. In this case, to prevent complexity due to the large number and variety of codes and numbers, each embodiment independently represents the lens groups, etc., using a combination of code and a number. Therefore, even if the same combination of code and a number is used between embodiments, it does not mean that they have the same configuration.

[0085] Tables 1 to 3 are shown below. Table 1 shows the specifications for the first embodiment, Table 2 for the second embodiment, and Table 3 for the third embodiment. In each embodiment, the d-line (wavelength λ=587.6nm) and the g-line (wavelength λ=435.8nm) were selected as the targets for calculating aberration characteristics.

[0086] In the [Overall Specifications] table, f represents the focal length of the entire lens system, FNO is the F-number, ω is the half-angle of view (in degrees), and Y is the image height. TL represents the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image plane when the variable magnification optical system is focused at infinity, plus Bf (back focus). Bf represents the distance along the optical axis from the lens surface closest to the image plane to the image plane when the variable magnification optical system is focused at infinity. These values ​​are shown for each magnification state: wide-angle end (W), intermediate focal length (M), first telephoto end (T1), and second telephoto end (T2).

[0087] Furthermore, in the [Overall Specifications] table, MA indicates the amount of movement of the lens group with the largest movement when changing magnification from the wide-angle end to the first telephoto end. MB indicates the amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end to the second telephoto end. MC indicates the amount of movement of the lens group with the smallest movement when changing magnification from the first telephoto end to the second telephoto end. MG2 indicates the amount of movement of the second lens group when changing magnification from the wide-angle end to the first telephoto end. D23 indicates the change in the distance between the second and third lens groups on the optical axis when changing magnification from the wide-angle end to the first telephoto end. MF1w indicates the amount of movement of the first focusing lens group when changing magnification from the wide-angle end to the first telephoto end. MF1t indicates the amount of movement of the first focusing lens group when changing magnification from the first telephoto end to the second telephoto end. MF2w indicates the amount of movement of the second focusing lens group when changing magnification from the wide-angle end to the first telephoto end. MF2t indicates the amount of movement of the second focusing lens group when changing magnification from the first telephoto end to the second telephoto end. Note that the magnification ratio (telephoto magnification) in the second telephoto state is greater than the magnification ratio (telephoto magnification) in the first telephoto state. In other words, the telephoto magnification can be increased by switching from the first telephoto state to the second telephoto state.

[0088] In the [Lens Specifications] table, the surface number indicates the order of the optical surfaces from the object side along the direction of light propagation, R is the radius of curvature of each optical surface (a positive value is given for surfaces where the center of curvature is located on the image side), D is the interplanar spacing, which is the distance along the optical axis from each optical surface to the next optical surface (or image plane), nd is the refractive index of the optical component material with respect to the d line, and νd is the Abbe number with respect to the d line of the optical component material. "∞" for the radius of curvature indicates a plane or aperture, and (Aperture S) indicates the aperture diaphragm S. The refractive index of air nd = 1.00000 is omitted. If an optical surface is aspherical, an asterisk (*) is placed next to the surface number, and the radius of curvature R column shows the paraxial radius of curvature.

[0089] In the table of [Aspherical Data], for the aspherical surfaces shown in [Lens Specifications], the shape is expressed by the following formula (A). X(y) represents the distance along the optical axis (sag amount) from the tangent plane at the vertex of the aspherical surface to the position on the aspherical surface at height y, R represents the radius of curvature of the reference sphere (paraxial radius of curvature), κ represents the conic constant, and Ai represents the i-th order aspherical coefficient. "E-n" represents "×10 -n ". For example, 1.234E-05 = 1.234×10 -5 . Note that the second-order aspherical coefficient A2 is 0 and its description is omitted.

[0090] X(y)=(y 2 / R) / {1+(1-κ×y 2 / R 2 ) 1 / 2}+A4×y 4 +A6×y 6 +A8×y 8 +A10×y 10 …(A)

[0091] In the table of [Variable Interval Data], it shows the surface interval at surface number i where the surface interval in the table of [Lens Specifications] is (Di). Also, the table of [Variable Interval Data] shows the surface interval in the infinity focus state and the surface interval in the close focus state. D0 represents the distance from the object to the lens surface closest to the object side in the zoom optical system.

[0092] In the table of [Lens Group Data], it shows the starting surface (the surface closest to the object side) and the focal length of each lens group.

[0093] Hereinafter, for all specification values, the published focal length f, radius of curvature R, surface interval D, and other lengths, etc. generally use "mm" when not otherwise specified. However, since the optical system can obtain the same optical performance even with proportional magnification or reduction, it is not limited to this.

[0094] The explanations of the tables so far are common to all embodiments, and duplicate explanations below are omitted.

[0095] (First Embodiment) The first embodiment will be described using Figures 1 to 5 and Table 1. Figure 1 is a diagram showing the lens configuration of the variable magnification optical system according to the first embodiment. The variable magnification optical system ZL(1) according to the first embodiment consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having positive refractive power, an eighth lens group G8 having negative refractive power, and a ninth lens group G9 having positive refractive power, all arranged in order from the object side along the optical axis.

[0096] When the zoom level changes from the wide-angle end (W) through the intermediate focal length (M) to the first telephoto end (T1), the second lens group G2, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 move along the optical axis as indicated by the arrows in Figure 1, changing the spacing between adjacent lens groups. In other words, when the zoom level changes from the wide-angle end to the first telephoto end, N1 = 6 lens groups move along the optical axis. Note that when the zoom level changes from the wide-angle end to the first telephoto end, the first lens group G1, the third lens group G3, and the ninth lens group G9 are fixed relative to the image plane I.

[0097] When changing from the first telephoto end state (T1) to the second telephoto end state (T2), the fourth lens group G4 and the sixth lens group G6 move toward the image plane along the optical axis along different trajectories (amount of movement), while the eighth lens group G8 moves toward the object along the optical axis. In other words, when changing from the first telephoto end state to the second telephoto end state, N2 = 3 lens groups move along the optical axis. When changing from the first telephoto end state to the second telephoto end state, the first lens group G1, the second lens group G2, the third lens group G3, the fifth lens group G5, the seventh lens group G7, and the ninth lens group G9 are fixed relative to the image plane I. In addition, an aperture diaphragm S is positioned between the third lens group G3 and the fourth lens group G4, and during the change in magnification, the aperture diaphragm S is fixed relative to the image plane I together with the third lens group G3. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this is the same in all the following examples.

[0098] The first lens group G1 consists of a bonded positive lens formed by joining a meniscus-shaped negative lens L11 with a convex surface facing the object and a biconvex positive lens L12, which are arranged in order from the object side along the optical axis, and a meniscus-shaped positive lens L13 with a convex surface facing the object.

[0099] The second lens group G2 consists of a meniscus-shaped negative lens L21 with its convex surface facing the object, a biconcave-shaped negative lens L22, a meniscus-shaped positive lens L23 with its convex surface facing the object, and a biconcave-shaped negative lens L24, all arranged in order from the object side along the optical axis. The second lens group G2 is the lens group with the largest amount of movement when changing magnification from the wide-angle end to the first telephoto end.

[0100] The third lens group G3 consists of a meniscus-shaped positive lens L31 with its convex surface facing the object, arranged in order from the object side along the optical axis; a meniscus-shaped positive lens L32 with its convex surface facing the object; and a bonded positive lens formed by joining a meniscus-shaped negative lens L33 with its convex surface facing the object and a meniscus-shaped positive lens L34 with its convex surface facing the object.

[0101] The fourth lens group G4 consists of a biconcave negative lens L41, which is arranged in order from the object side along the optical axis, and a bonded negative lens formed by joining a biconcave negative lens L42 and a meniscus-shaped positive lens L43 with its convex side facing the object. The fourth lens group G4 is the lens group with the largest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.

[0102] The fifth lens group G5 consists of a biconvex positive lens L51 and a bonded positive lens formed by joining a biconvex positive lens L52 and a biconcave negative lens L53, which are arranged in order from the object side along the optical axis. The lens surface of the positive lens L51 on the object side is aspherical.

[0103] The sixth lens group G6 consists of a biconvex positive lens L61. The sixth lens group G6 is the lens group with the smallest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.

[0104] The seventh lens group G7 consists of a meniscus-shaped positive lens L71 with its concave surface facing the object, a meniscus-shaped negative lens L72 with its convex surface facing the object, a bonded negative lens formed by joining a biconvex positive lens L73 and a biconcave negative lens L74, and a biconvex positive lens L75, all arranged in order from the object side along the optical axis. The meniscus-shaped negative lens L72 has an aspherical lens surface on the image plane side.

[0105] The eighth lens group G8 consists of a meniscus-shaped negative lens L81 with its concave surface facing the object.

[0106] The ninth lens group G9 consists of a meniscus-shaped negative lens L91 with its concave surface facing the object, and a biconvex-shaped positive lens L92, arranged in order from the object side along the optical axis. The image plane I is positioned on the image side of the ninth lens group G9.

[0107] In this embodiment, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, the eighth lens group G8, and the ninth lens group G9 constitute the rear group GR. In the rear group GR, the fourth lens group G4 corresponds to the first focusing lens group GF1, and the sixth lens group G6 corresponds to the second focusing lens group GF2. Furthermore, the eighth lens group G8 corresponds to the third focusing lens group GF3, and the ninth lens group G9 corresponds to the final lens group GE.

[0108] In the wide-angle setting, when focusing from an object at infinity to a nearby object, the first focusing lens group GF1 (fourth lens group G4) and the third focusing lens group GF3 (eighth lens group G8) move toward the image plane along the optical axis along different trajectories (amount of movement), while the second focusing lens group GF2 (sixth lens group G6) moves toward the object along the optical axis. In the intermediate focal length setting and the first telephoto setting, when focusing from an object at infinity to a nearby object, the first focusing lens group GF1 (fourth lens group G4) and the second focusing lens group GF2 (sixth lens group G6) move toward the object along the optical axis along different trajectories (amount of movement), while the third focusing lens group GF3 (eighth lens group G8) moves toward the image plane along the optical axis. In the second telephoto end state, when focusing from an object at infinity to a nearby object, the second focusing lens group GF2 (sixth lens group G6) moves towards the object along the optical axis, and the third focusing lens group GF3 (eighth lens group G8) moves towards the image plane along the optical axis. Also, when changing from the first telephoto end state to the second telephoto end state, the first focusing lens group GF1 (fourth lens group G4) and the second focusing lens group GF2 (sixth lens group G6) move towards the image plane along the optical axis along different trajectories (amount of movement), and the third focusing lens group GF3 (eighth lens group G8) moves towards the object along the optical axis.

[0109] As described above, the variable magnification optical system ZL(1) according to the first embodiment is provided in the photographic lens 3 (see Figure 16) attached to the body 2 of the camera 1. The photographic lens 3 is also called the lens barrel. The photographic lens 3 (lens barrel) contains the lens position control mechanism CH(1) according to the first embodiment, which is schematically shown in Figure 2 and includes the first to ninth group frames H1 to H9, a fixed cylinder JA, and a cam cylinder JC. The first lens group G1 is held in the first group frame H1. The second lens group G2 is held in the second group frame H2. The third lens group G3 is held in the third group frame H3. The fourth lens group G4 is held in the fourth group frame H4. The fifth lens group G5 is held in the fifth group frame H5. The sixth lens group G6 is held in the sixth group frame H6. The seventh lens group G7 is held in the seventh group frame H7. The eighth lens group G8 is held in the eighth lens group frame H8. The ninth lens group G9 is held in the ninth lens group frame H9.

[0110] A cam cylinder JC is rotatably positioned relative to the fixed cylinder JA on its outer circumference. The first group frame H1 is fixed to the object side of the fixed cylinder JA. The ninth group frame H9 is fixed to the image plane side of the fixed cylinder JA. Inside the fixed cylinder JA, in order from the object side, the second group frame H2, the third group frame H3, the fourth group cylinder member U4, the fifth group frame H5, the sixth group cylinder member U6, the seventh group frame H7, and the eighth group cylinder member U8 are arranged. The third group frame H3 is fixed to the inside of the fixed cylinder JA. The fourth group frame H4 is positioned inside the fourth group cylinder member U4. The sixth group frame H6 is positioned inside the sixth group cylinder member U6. The eighth group frame H8 is positioned inside the eighth group cylinder member U8. Furthermore, the inner circumference of the fixed cylinder JA is provided with multiple guide bars extending along the optical axis direction, and the corresponding guide grooves of the lens group frame and cylinder member engage with them.

[0111] Multiple cam grooves are formed in the cam cylinder JC, and the corresponding cam followers of the lens group frame and cylindrical member engage with them. Furthermore, on the outer circumference of the cam cylinder JC, as shown by the dashed line in Figure 2, the first operating ring K1 and the second operating ring K2 are rotatably mounted relative to the fixed cylinder JA.

[0112] The first operating ring K1 is a so-called zoom ring and can be rotated by the user. Inside the first operating ring K1 is a first detection unit (not shown) that detects the amount of rotation of the first operating ring K1. When the first detection unit detects the rotation of the first operating ring K1, it outputs the amount of rotation and the rotation speed to a control unit (not shown) inside the photographic lens 3 (lens barrel). On the outer circumference of the first operating ring K1 is an operation switch (not shown) that is used to expand the rotatable range of the first operating ring K1 (for example, by pressing it). The user can perform a zoom change operation between the wide-angle end state and the first telephoto end state by rotating the first operating ring K1 without pressing the operation switch. The user can perform a zoom change operation between the wide-angle end state and the second telephoto end state by rotating the first operating ring K1 while pressing the operation switch.

[0113] The second operating ring K2 can be rotated by the user, and the function operated by the rotation can be set on the camera body 2 or the shooting lens 3. For example, the user can change optical characteristics such as the focus position, focal length, or aperture value by rotating the second operating ring K2. A second detection unit (not shown) for detecting the amount of rotation of the second operating ring K2 is provided on the inner diameter side of the second operating ring K2. When the second operating ring K2 is rotated by the user, the second detection unit detects the amount and speed of rotation of the second operating ring K2 and outputs it to a control unit (not shown) inside the shooting lens 3 (lens barrel). The control unit drives and controls motors (such as the fourth group drive motor, sixth group drive motor, and eighth group drive motor described later) for changing the optical characteristics according to the amount of rotation of the second operating ring K2.

[0114] A fourth group drive unit (not shown) is provided on the fourth group barrel member U4. The fourth group drive unit drives the fourth group frame H4 in the optical axis direction. The fourth group drive unit can drive the fourth lens group G4 (first focusing lens group GF1) held in the fourth group frame H4 in the optical axis direction not only when focusing, but also when changing magnification from the first telephoto end state to the second telephoto end state. For example, the fourth group drive unit comprises a fourth group drive motor (not shown), a fourth group lead screw (not shown), and a fourth group rack (not shown). The fourth group drive motor is, for example, a stepping motor and is fixed to the fourth group barrel member U4. The fourth group lead screw is formed in an axial shape with a threaded portion extending in the optical axis direction and rotates in connection with the output shaft of the fourth group drive motor. The fourth group rack is screwed into the threaded portion of the fourth group lead screw and connected to the fourth group frame H4. Furthermore, the drive mechanism that drives the fourth group frame H4 in the optical axis direction can be modified as appropriate.

[0115] A sixth group drive unit (not shown) is provided in the sixth group barrel member U6. The sixth group drive unit drives the sixth group frame H6 in the optical axis direction. The sixth group drive unit can drive the sixth lens group G6 (second focusing lens group GF2), which is held in the sixth group frame H6, in the optical axis direction not only when focusing, but also when changing magnification from the first telephoto end state to the second telephoto end state. For example, the sixth group drive unit comprises a sixth group drive motor (not shown), a sixth group lead screw (not shown), and a sixth group rack (not shown). The sixth group drive motor is, for example, a stepping motor and is fixed to the sixth group barrel member U6. The sixth group lead screw is formed in an axial shape with a threaded portion extending in the optical axis direction and rotates in connection with the output shaft of the sixth group drive motor. The sixth group rack is screwed into the threaded portion of the sixth group lead screw and connected to the sixth group frame H6. Furthermore, the drive mechanism that drives the sixth group frame H6 in the optical axis direction can be modified as appropriate.

[0116] The eighth lens group barrel member U8 is provided with an eighth lens group drive unit (not shown). The eighth lens group drive unit drives the eighth lens group frame H8 in the optical axis direction. The eighth lens group drive unit can drive the eighth lens group G8 (third focusing lens group GF3), which is held in the eighth lens group frame H8, in the optical axis direction not only when focusing, but also when changing magnification from the first telephoto end state to the second telephoto end state. For example, the eighth lens group drive unit comprises an eighth lens group drive motor (not shown), an eighth lens group lead screw (not shown), and an eighth lens group rack (not shown). The eighth lens group drive motor is, for example, a stepping motor and is fixed to the eighth lens group barrel member U8. The eighth lens group lead screw is formed in an axial shape with a threaded portion extending in the optical axis direction and rotates in connection with the output shaft of the eighth lens group drive motor. The eighth lens group rack is screwed into the threaded portion of the eighth lens group lead screw and connected to the eighth lens group frame H8. Furthermore, the drive mechanism that drives the 8th group frame H8 in the optical axis direction can be modified as appropriate.

[0117] When changing magnification from the wide-angle end state to the first telephoto end state, the second group frame H2, the fourth group cylinder member U4, the fifth group frame H5, the sixth group cylinder member U6, the seventh group frame H7, and the eighth group cylinder member U8 are driven in the optical axis direction by the rotation of the cam cylinder JC, which rotates in response to the rotation of the first operating ring K1. When changing magnification from the first telephoto end state to the second telephoto end state, or when focusing, the fourth group frame H4 is driven in the optical axis direction relative to the fourth group cylinder member U4 by a fourth group drive unit (not shown) provided on the fourth group cylinder member U4 in response to the rotation of the first operating ring K1 or the second operating ring K2. The sixth group frame H6 is also driven in the optical axis direction relative to the sixth group cylinder member U6 by a sixth group drive unit (not shown) provided on the sixth group cylinder member U6 in response to the rotation of the first operating ring K1 or the second operating ring K2. The eighth group frame H8 is also driven in the optical axis direction relative to the eighth group cylindrical member U8 by an eighth group drive unit (not shown) provided on the eighth group cylindrical member U8, in accordance with the rotation of the first operating ring K1 or the second operating ring K2.

[0118] Specifically, the second lens group G2, the fifth lens group G5, and the seventh lens group G7 are mechanically driven in the optical axis direction when the first operating ring K1 is rotated. In addition, the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 are mechanically and electrically (motor drive control) driven in the optical axis direction when the first operating ring K1 is rotated, and are electrically driven in the optical axis direction when the second operating ring K2 is rotated and focusing is instructed.

[0119] In this way, the second lens group G2, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 are driven in the direction of the optical axis when the magnification changes from the wide-angle end state to the first telephoto end state. As described above, the magnification from the wide-angle end state (W) through the intermediate focal point state (M) to the first telephoto end state (T1) continuously changes the focal length of the entire optical system while maintaining image formation on the same plane, and the magnification is controlled so that the focal length state is appropriate for each state from the wide-angle end state (W) to the first telephoto end state (T1). This is also the case in the second and third embodiments described below.

[0120] Furthermore, the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 are driven in the optical axis direction when changing magnification from the first telephoto end state to the second telephoto end state. As mentioned above, the change (switching) from the first telephoto end state (T1) to the second telephoto end state (T2) does not require a continuous change in focal length; it is sufficient that the image is in focus and formed at least in the first telephoto end state (T1) and the second telephoto end state (T2), and imaging performance in between is not required. Therefore, the change in magnification from the first telephoto end state (T1) to the second telephoto end state (T2) does not require continuous control like the change from the wide-angle end state (W) to the first telephoto end state (T1), and may be intermittent (discrete). This is also true in the second and third embodiments described below.

[0121] Furthermore, the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 are driven in the optical axis direction when focusing. In this embodiment, the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 may be driven electrically in the optical axis direction, not limited to mechanically and electrically (motor drive control). The second lens group G2, the fifth lens group G5, and the seventh lens group G7 may be driven electrically in the optical axis direction, not limited to mechanically.

[0122] Table 1 below lists the specifications of the variable magnification optical system according to the first embodiment.

[0123] (Table 1) [Overall Specifications] Scale ratio (W→T1) = 2.796 Scale ratio (W→T2) = 4.066 MA=40.034 MB=16.294 MC=0.838 MG2=40.034 D23=40.034 MF1w=0.070 MF1t=16.294 MF2w = 1.984 MF2t = 0.838 WM T1 T2 f 71.548 135.050 200.028 290.942 FNO 2.880 2.880 2.880 4.190 ω 16.511 8.764 5.920 4.036 Y 21.700 21.700 21.700 21.700 TL 250.032 250.032 250.032 250.032 Bf 11.741 11.741 11.741 11.741 [Lens Specifications] Face number RD nd νd 1 122.864 2.800 2.00100 29.12 2 90.022 10.167 1.43700 95.10 3 -414.107 0.234 4 77.712 7.561 1.49782 82.57 5 295.979 (D5) 6 56.998 1.900 1.80400 46.60 7 31.804 7.084 8 -4966.831 1.700 1.59319 67.90 9 67.160 0.100 10 44.520 4.643 1.78880 28.43 11 110.699 4.209 12 -79.535 1.938 1.59319 67.90 13 145.761 (D13) 14 158.706 2.960 1.85000 27.03 15 1838.648 0.100 16 51.122 5.386 1.59319 67.90 17 376.813 0.248 18 53.979 1.988 1.95000 29.37 19 31.619 6.264 1.59319 67.90 20 125.967 2.816 21 ∞ (D21) (Aperture S) 22 -323.008 1.690 1.48749 70.32 23 48.793 4.205 24 -102.551 1.630 1.72916 54.61 25 66.748 3.370 1.94595 17.98 26 261.516 (D26) 27* 109.977 5.481 1.72916 54.61 28 -79.623 0.100 29 111.650 6.633 1.55032 75.50 30 -51.225 1.922 1.84666 23.80 31 147.362 (D31) 32 56.533 5.446 1.59319 67.90 33 -217.682 (D33) 34 -2926.248 2.671 1.72916 54.61 35 -141.449 0.104 36 60.090 1.504 1.90265 35.77 37* 34.056 5.025 38 489.405 4.385 1.95000 29.37 39 -55.620 1.609 1.81600 46.59 40 49.501 2.112 41 43.776 5.208 1.69895 30.13 42 -284.027 (D42) 43 -59.154 1.545 1.95375 32.33 44 -465.956 (D44) 45 -28.519 1.736 1.88300 40.69 46 -49.853 0.105 47 531.811 5.623 1.75211 25.05 48 -64.326 Bf [Aspherical data] Page 27 κ=1.000,A4=-1.64920E-06,A6=3.15497E-10,A8=-5.63176E-13,A10=5.03223E-16 Page 37 κ=1.000,A4=-5.24407E-07,A6=1.13434E-10,A8=-1.32855E-12,A10=4.32537E-15 [Variable interval data] Infinity focus state WM T1 T2 Focal length 71.548 135.050 200.028 290.942 D0 ∞ ∞ ∞ ∞ D5 1.500 27.147 41.533 41.533 D13 41.615 15.968 1.581 1.581 D21 1.873 2.684 1.943 18.237 D26 24.719 19.898 17.795 1.500 D31 6.344 6.130 11.214 12.053 D33 8.357 6.869 2.414 1.575 D42 17.020 18.526 16.675 2.976 D44 12.661 16.866 20.933 34.632 Bf 11.741 11.741 11.741 11.741 Close-range focus WM T1 T2 Magnification -0.205 -0.147 -0.165 -0.100 D0 250.000 700.000 900.000 3000.000 D5 1.500 27.147 41.533 41.533 D13 41.615 15.968 1.581 1.581 D21 2.113 2.058 1.863 18.237 D26 24.478 20.524 17.874 1.500 D31 2.094 1.600 3.491 3.991 D33 12.607 11.399 10.137 9.637 D42 23.533 28.326 31.299 4.992 D44 6.149 7.066 6.310 32.617 Bf 11.741 11.741 11.741 11.741 [Lens group data] Group starting plane focal length G1 1 130.513 G2 6 -45.453 G3 14 57.730 G4 22 -51.346 G5 27 97.646 G6 32 76.219 G7 34 987.656 G8 43 -71.174 G9 45 849.550

[0124] Figure 3 shows the aberration diagrams for the variable magnification optical system according to the first embodiment when focused at infinity at the wide-angle end. Figure 4 shows the aberration diagrams for the variable magnification optical system according to the first embodiment when focused at infinity at the first telephoto end. Figure 5 shows the aberration diagrams for the variable magnification optical system according to the first embodiment when focused at infinity at the second telephoto end. In each aberration diagram, FNO indicates the F number and Y indicates the image height. In the spherical aberration diagram, the value of the F number corresponding to the maximum aperture is shown, in the astigmatism and distortion diagrams, the maximum value of the image height is shown, and in the coma aberration diagram, the values ​​of each image height are shown. d indicates the d line (wavelength λ=587.6nm), and g indicates the g line (wavelength λ=435.8nm). In the astigmatism diagram, the solid line indicates the sagittal image plane and the dashed line indicates the meridional image plane. In the aberration diagrams of the embodiments shown below, the same reference numerals as in this embodiment are used, and redundant explanations are omitted.

[0125] From the various aberration diagrams, it can be seen that the variable magnification optical system according to the first embodiment has excellent imaging performance, with aberrations well corrected from the wide-angle end to the first telephoto end and from the first telephoto end to the second telephoto end.

[0126] (Second example) The second embodiment will be described using Figures 6 to 10 and Table 2. Figure 6 is a diagram showing the lens configuration of the variable magnification optical system according to the second embodiment. The variable magnification optical system ZL(2) according to the second embodiment consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having negative refractive power, and an eighth lens group G8 having negative refractive power, all arranged in order from the object side along the optical axis.

[0127] When the zoom level changes from the wide-angle end (W) through the intermediate focal length (M) to the first telephoto end (T1), the second lens group G2, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 move along the optical axis as indicated by the arrows in Figure 6, changing the spacing between adjacent lens groups. In other words, when the zoom level changes from the wide-angle end to the first telephoto end, N1 = 5 lens groups move along the optical axis. Note that when the zoom level changes from the wide-angle end to the first telephoto end, the first lens group G1, the third lens group G3, and the eighth lens group G8 are fixed relative to the image plane I.

[0128] When changing from the first telephoto end state (T1) to the second telephoto end state (T2), the fourth lens group G4 and the sixth lens group G6 move toward the image plane along the optical axis along different trajectories (amount of movement). That is, when changing from the first telephoto end state to the second telephoto end state, N2 = 2 lens groups move along the optical axis. When changing from the first telephoto end state to the second telephoto end state, the first lens group G1, the second lens group G2, the third lens group G3, the fifth lens group G5, the seventh lens group G7, and the eighth lens group G8 are fixed relative to the image plane I. In addition, an aperture diaphragm S is positioned between the third lens group G3 and the fourth lens group G4, and during the change in magnification, the aperture diaphragm S is fixed relative to the image plane I together with the third lens group G3.

[0129] The first lens group G1 consists of a bonded positive lens formed by joining a meniscus-shaped negative lens L11 with a convex surface facing the object and a biconvex positive lens L12, which are arranged in order from the object side along the optical axis, and a meniscus-shaped positive lens L13 with a convex surface facing the object.

[0130] The second lens group G2 consists of a meniscus-shaped negative lens L21 with its convex surface facing the object, a biconcave-shaped negative lens L22, a meniscus-shaped positive lens L23 with its convex surface facing the object, and a biconcave-shaped negative lens L24, all arranged in order from the object side along the optical axis. The second lens group G2 is the lens group with the largest amount of movement when changing magnification from the wide-angle end to the first telephoto end.

[0131] The third lens group G3 consists of a meniscus-shaped positive lens L31 with its convex surface facing the object, arranged in order from the object side along the optical axis; a meniscus-shaped positive lens L32 with its convex surface facing the object; and a bonded positive lens formed by joining a meniscus-shaped negative lens L33 with its convex surface facing the object and a meniscus-shaped positive lens L34 with its convex surface facing the object.

[0132] The fourth lens group G4 consists of a meniscus-shaped negative lens L41 with its convex surface facing the object, arranged in order from the object side along the optical axis, and a bonded negative lens formed by joining a biconcave-shaped negative lens L42 and a meniscus-shaped positive lens L43 with its convex surface facing the object. The fourth lens group G4 is the lens group with the largest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.

[0133] The fifth lens group G5 consists of a biconvex positive lens L51 and a bonded positive lens formed by joining a biconvex positive lens L52 and a biconcave negative lens L53, which are arranged in order from the object side along the optical axis. The lens surface of the positive lens L51 on the object side is aspherical.

[0134] The sixth lens group G6 consists of a biconvex positive lens L61. The sixth lens group G6 is the lens group with the smallest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.

[0135] The seventh lens group G7 consists of a biconvex positive lens L71, a meniscus-shaped negative lens L72 with its convex surface facing the object, a bonded negative lens formed by joining a meniscus-shaped positive lens L73 with its concave surface facing the object and a biconcave negative lens L74, and a biconvex positive lens L75, all arranged in order from the object side along the optical axis. The image plane side of the meniscus-shaped negative lens L72 is aspherical.

[0136] The eighth lens group G8 consists of a meniscus-shaped negative lens L81 with its concave surface facing the object, and a biconvex-shaped positive lens L82, arranged in order from the object side along the optical axis. The image plane I is positioned on the image side of the eighth lens group G8.

[0137] In this embodiment, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 constitute the rear group GR. In the rear group GR, the fourth lens group G4 corresponds to the first focusing lens group GF1, the sixth lens group G6 corresponds to the second focusing lens group GF2, and the eighth lens group G8 corresponds to the final lens group GE.

[0138] In the wide-angle, intermediate focal length, and second telephoto end states, when focusing from an object at infinity to a nearby object, the first focusing lens group GF1 (fourth lens group G4) and the second focusing lens group GF2 (sixth lens group G6) move toward the object along the optical axis along different trajectories (amount of movement). In the first telephoto end state, when focusing from an object at infinity to a nearby object, only the second focusing lens group GF2 (sixth lens group G6) moves toward the object along the optical axis. Furthermore, when changing magnification from the first telephoto end state to the second telephoto end state, the first focusing lens group GF1 (fourth lens group G4) and the second focusing lens group GF2 (sixth lens group G6) move toward the image plane along the optical axis along different trajectories (amount of movement).

[0139] As described above, the variable magnification optical system ZL(2) according to the second embodiment is provided on the photographic lens 3 (see Figure 16) attached to the camera body 2 of the camera 1. The photographic lens 3 (lens barrel) contains a lens position control mechanism CH(2) according to the second embodiment, which is schematically shown in Figure 7 and includes the first to eighth group frames H1 to H8, a fixed cylinder JA, and a cam cylinder JC. The first lens group G1 is held in the first group frame H1. The second lens group G2 is held in the second group frame H2. The third lens group G3 is held in the third group frame H3. The fourth lens group G4 is held in the fourth group frame H4. The fifth lens group G5 is held in the fifth group frame H5. The sixth lens group G6 is held in the sixth group frame H6. The seventh lens group G7 is held in the seventh group frame H7. The eighth lens group G8 is held in the eighth group frame H8.

[0140] A cam cylinder JC is rotatably positioned relative to the fixed cylinder JA on its outer circumference. The first group frame H1 is fixed to the object side of the fixed cylinder JA. The eighth group frame H8 is fixed to the image plane side of the fixed cylinder JA. Inside the fixed cylinder JA, in order from the object side, the second group frame H2, the third group frame H3, the fourth group cylinder member U4, the fifth group frame H5, the sixth group cylinder member U6, and the seventh group frame H7 are arranged. The third group frame H3 is fixed to the inside of the fixed cylinder JA. The fourth group frame H4 is positioned inside the fourth group cylinder member U4. The sixth group frame H6 is positioned inside the sixth group cylinder member U6. In addition, multiple guide bars extending along the optical axis are provided on the inner circumference of the fixed cylinder JA, and the guide grooves of the corresponding lens group frames and cylinder members are engaged with them.

[0141] Multiple cam grooves are formed in the cam cylinder JC, and the corresponding cam followers of the lens group frame and cylindrical member engage with them. Furthermore, on the outer circumference of the cam cylinder JC, as shown by the dashed line in Figure 7, a first operating ring K1 and a second operating ring K2 are rotatably provided relative to the fixed cylinder JA. The first operating ring K1 and the second operating ring K2 have the same configuration as the first operating ring K1 and the second operating ring K2 in the first embodiment, and a detailed explanation is omitted.

[0142] The fourth group cylinder member U4 is provided with a fourth group drive unit (not shown). The fourth group drive unit drives the fourth group frame H4 in the optical axis direction. The sixth group cylinder member U6 is provided with a sixth group drive unit (not shown). The sixth group drive unit drives the sixth group frame H6 in the optical axis direction. The fourth group drive unit and the sixth group drive unit have the same configuration as the fourth group drive unit and the sixth group drive unit according to the first embodiment, and a detailed explanation is omitted.

[0143] When changing magnification from the wide-angle end to the first telephoto end, the second group frame H2, the fourth group barrel member U4, the fifth group frame H5, the sixth group barrel member U6, and the seventh group frame H7 are driven in the optical axis direction by the rotation of the cam barrel JC, which rotates in response to the rotation of the first operating ring K1. When changing magnification from the first telephoto end to the second telephoto end, or when focusing, the fourth group frame H4 is driven in the optical axis direction relative to the fourth group barrel member U4 by a fourth group drive unit (not shown) provided on the fourth group barrel member U4 in response to the rotation of the first operating ring K1 or the second operating ring K2. The sixth group frame H6 is also driven in the optical axis direction relative to the sixth group barrel member U6 by a sixth group drive unit (not shown) provided on the sixth group barrel member U6 in response to the rotation of the first operating ring K1 or the second operating ring K2.

[0144] Specifically, the second lens group G2, the fifth lens group G5, and the seventh lens group G7 are mechanically driven in the optical axis direction when the first operating ring K1 is rotated. In addition, the fourth lens group G4 and the sixth lens group G6 are mechanically and electrically (motor drive control) driven in the optical axis direction when the first operating ring K1 is rotated, and are electrically driven in the optical axis direction when the second operating ring K2 is rotated and focusing is instructed.

[0145] In this manner, the second lens group G2, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 are driven in the optical axis direction when changing magnification from the wide-angle end state to the first telephoto end state. Furthermore, the fourth lens group G4 and the sixth lens group G6 are driven in the optical axis direction when changing magnification from the first telephoto end state to the second telephoto end state. In addition, the fourth lens group G4 and the sixth lens group G6 are driven in the optical axis direction when focusing. In this embodiment, the fourth lens group G4 and the sixth lens group G6 may be driven electrically in the optical axis direction, not limited to mechanically and electrically (motor drive control). The second lens group G2, the fifth lens group G5, and the seventh lens group G7 may be driven electrically in the optical axis direction, not limited to mechanically.

[0146] Table 2 below lists the specifications of the variable magnification optical system according to the second embodiment.

[0147] (Table 2) [Overall Specifications] Scale ratio (W→T1) = 2.796 Scale ratio (W→T2) = 4.066 MA=39.241 MB=19.056 MC=1.585 MG2=39.241 D23=39.241 MF1w=5.842 MF1t=19.056 MF2w = 8.376 MF2t = 1.585 WM T1 T2 f 71.533 135.021 199.988 290.888 FNO 2.880 2.880 2.880 4.190 ω 16.505 8.743 5.900 4.061 Y 21.700 21.700 21.700 21.700 TL 250.011 250.011 250.011 250.011 Bf 17.789 17.789 17.789 17.789 [Lens Specifications] Face number RD nd νd 1 114.544 2.800 2.00100 29.12 2 83.656 10.935 1.43700 95.10 3 -325.490 0.100 4 76.421 7.548 1.49782 82.57 5 301.176 (D5) 6 42.823 2.000 1.80420 46.50 7 27.561 9.202 8 -421.746 1.800 1.59282 68.62 9 55.874 0.100 10 37.770 4.827 1.78880 28.43 11 101.335 3.721 12 -78.344 1.781 1.59282 68.62 13 78.190 (D13) 14 77.705 3.571 1.84666 23.80 15 360.519 0.100 16 40.850 5.243 1.59282 68.62 17 212.184 0.100 18 66.204 1.728 2.00100 29.12 19 26.080 6.325 1.59282 68.62 20 129.745 2.463 21 ∞ (D21) (Aperture S) 22 862.907 1.523 1.51860 69.89 23 86.284 2.756 24 -83.791 1.498 1.72916 54.61 25 59.685 2.642 1.95906 17.47 26 103.445 (D26) 27* 98.633 6.161 1.72916 54.68 28 -77.363 0.100 29 114.635 6.339 1.55032 75.50 30 -67.817 1.943 1.85451 25.15 31 389.754 (D31) 32 54.843 6.404 1.59282 68.62 33 -147.636 (D33) 34 222.852 2.429 1.71300 53.87 35 -1960.235 0.100 36 82.264 1.500 1.91082 35.25 37* 30.467 5.759 38 -459.309 4.400 2.00100 29.12 39 -45.938 1.599 1.81600 46.62 40 54.968 2.000 41 45.009 5.060 1.68948 31.02 42 -473.780 (D42) 43 -29.972 1.625 1.95375 32.33 44 -103.892 0.100 45 78.373 6.295 1.62004 36.30 46 -97.421 Bf [Aspherical data] Page 27 κ=1.000,A4=-2.00672E-06,A6=2.68755E-10,A8=-3.53434E-13,A10=2.25579E-16 Page 37 κ=1.000,A4=-6.78662E-07,A6=-6.07215E-10,A8=-3.52567E-13,A10=6.36352E-16 [Variable interval data] Infinity focus state WM T1 T2 Focal length 71.533 135.021 199.988 290.888 D0 ∞ ∞ ∞ ∞ D5 1.500 28.444 40.741 40.741 D13 40.741 13.797 1.500 1.500 D21 7.342 5.711 1.500 20.556 D26 20.555 21.704 20.556 1.500 D31 13.313 7.408 10.778 12.363 D33 9.991 8.837 3.084 1.499 D42 14.203 21.743 29.486 29.486 Bf 17.789 17.789 17.789 17.789 Close-range focus WM T1 T2 Magnification -0.199 -0.139 -0.174 -0.096 D0 250.000 700.000 900.000 3000.000 D5 1.500 28.444 40.741 40.741 D13 40.741 13.797 1.500 1.500 D21 5.071 1.500 1.500 19.783 D26 22.826 25.916 20.556 2.273 D31 9.035 2.906 1.492 4.633 D33 14.269 13.340 12.370 9.229 D42 14.203 21.743 29.486 29.486 Bf 17.789 17.789 17.789 17.789 [Lens group data] Group starting plane focal length G1 1 122.121 G2 6 -39.013 G3 14 60.126 G4 22 -50.190 G5 27 65.085 G6 32 68.258 G7 34 -105.133 G8 43 -135.867

[0148] Figure 8 shows the aberration diagrams for the variable magnification optical system according to the second embodiment when focused at infinity at the wide-angle end. Figure 9 shows the aberration diagrams for the variable magnification optical system according to the second embodiment when focused at infinity at the first telephoto end. Figure 10 shows the aberration diagrams for the variable magnification optical system according to the second embodiment when focused at infinity at the second telephoto end. From each aberration diagram, it can be seen that the variable magnification optical system according to the second embodiment has excellent imaging performance, with aberrations well corrected from the wide-angle end to the first telephoto end and from the first telephoto end to the second telephoto end.

[0149] (Third embodiment) The third embodiment will be described using Figures 11 to 15 and Table 3. Figure 11 is a diagram showing the lens configuration of the variable magnification optical system according to the third embodiment. The variable magnification optical system ZL(3) according to the third embodiment consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having positive refractive power, an eighth lens group G8 having negative refractive power, and a ninth lens group G9 having negative refractive power, all arranged in order from the object side along the optical axis.

[0150] When the zoom level changes from the wide-angle end (W) through the intermediate focal length (M) to the first telephoto end (T1), the second lens group G2, the third lens group G3, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 move along the optical axis as indicated by the arrows in Figure 11, changing the spacing between adjacent lens groups. In other words, when the zoom level changes from the wide-angle end to the first telephoto end, N1 = 6 lens groups move along the optical axis. Note that when the zoom level changes from the wide-angle end to the first telephoto end, the first lens group G1, the fourth lens group G4, and the ninth lens group G9 are fixed relative to the image plane I.

[0151] When changing from the first telephoto end state (T1) to the second telephoto end state (T2), the fifth lens group G5 and the seventh lens group G7 move toward the image plane along the optical axis along different trajectories (amount of movement). That is, when changing from the first telephoto end state to the second telephoto end state, N2 = 2 lens groups move along the optical axis. When changing from the first telephoto end state to the second telephoto end state, the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the sixth lens group G6, the eighth lens group G8, and the ninth lens group G9 are fixed relative to the image plane I. In addition, an aperture diaphragm S is positioned between the third lens group G3 and the fourth lens group G4, and during the change in magnification, the aperture diaphragm S is fixed relative to the image plane I together with the fourth lens group G4.

[0152] The first lens group G1 consists of a bonded positive lens formed by joining a meniscus-shaped negative lens L11 with a convex surface facing the object and a biconvex positive lens L12, which are arranged in order from the object side along the optical axis, and a meniscus-shaped positive lens L13 with a convex surface facing the object.

[0153] The second lens group G2 consists of a meniscus-shaped negative lens L21 with its convex surface facing the object, a biconcave-shaped negative lens L22, a meniscus-shaped positive lens L23 with its convex surface facing the object, and a biconcave-shaped negative lens L24, all arranged in order from the object side along the optical axis. The second lens group G2 is the lens group with the largest amount of movement when changing magnification from the wide-angle end to the first telephoto end.

[0154] The third lens group G3 consists of a biconvex positive lens L31 and a meniscus positive lens L32, which are arranged in order from the object side along the optical axis, with the convex side facing the object.

[0155] The fourth lens group G4 consists of a bonded negative lens formed by joining a meniscus-shaped negative lens L41 with a convex surface facing the object side and a meniscus-shaped positive lens L42 with a convex surface facing the object side, arranged in order from the object side along the optical axis.

[0156] The fifth lens group G5 consists of a biconcave negative lens L51, a meniscus-shaped negative lens L52 with its convex surface facing the object, and a meniscus-shaped positive lens L53 with its convex surface facing the object, all arranged in order from the object side along the optical axis. The fifth lens group G5 is the lens group with the largest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.

[0157] The sixth lens group G6 consists of a biconvex positive lens L61 arranged in order from the object side along the optical axis, and a bonded positive lens formed by joining a meniscus-shaped negative lens L62 with its convex surface facing the object side and a biconvex positive lens L63.

[0158] The seventh lens group G7 consists of a meniscus-shaped positive lens L71 with its convex surface facing the object. The seventh lens group G7 is the lens group with the smallest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.

[0159] The eighth lens group G8 consists of a meniscus-shaped negative lens L81 with its convex surface facing the object, and a biconvex-shaped positive lens L82, arranged sequentially from the object side along the optical axis. The object-side lens surface of the meniscus-shaped negative lens L81 is aspherical.

[0160] The ninth lens group G9 consists of a meniscus-shaped negative lens L91 with its concave surface facing the object, and a biconvex-shaped positive lens L92, arranged sequentially from the object side along the optical axis. The object-side lens surface of the meniscus-shaped negative lens L91 is aspherical. The image plane I is positioned on the image side of the ninth lens group G9.

[0161] In this embodiment, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, the eighth lens group G8, and the ninth lens group G9 constitute the rear group GR. In the rear group GR, the fifth lens group G5 corresponds to the first focusing lens group GF1, the seventh lens group G7 corresponds to the second focusing lens group GF2, and the ninth lens group G9 corresponds to the final lens group GE.

[0162] In the wide-angle, intermediate focal length, and first telephoto end states, when focusing from an object at infinity to a nearby object, the first focusing lens group GF1 (fifth lens group G5) and the second focusing lens group GF2 (seventh lens group G7) move along the optical axis toward the object with different trajectories (amount of movement). In the second telephoto end state, when focusing from an object at infinity to a nearby object, only the second focusing lens group GF2 (seventh lens group G7) moves along the optical axis toward the object. Furthermore, when changing magnification from the first telephoto end state to the second telephoto end state, the first focusing lens group GF1 (fifth lens group G5) and the second focusing lens group GF2 (seventh lens group G7) move along the optical axis toward the image plane with different trajectories (amount of movement).

[0163] As described above, the variable magnification optical system ZL(3) according to the third embodiment is provided on the photographic lens 3 (see Figure 16) attached to the body 2 of the camera 1. The photographic lens 3 (lens barrel) contains a lens position control mechanism CH(3) according to the third embodiment, which is schematically shown in Figure 12 and includes the first to ninth group frames H1 to H9, a fixed cylinder JA, and a cam cylinder JC. The first lens group G1 is held in the first group frame H1. The second lens group G2 is held in the second group frame H2. The third lens group G3 is held in the third group frame H3. The fourth lens group G4 is held in the fourth group frame H4. The fifth lens group G5 is held in the fifth group frame H5. The sixth lens group G6 is held in the sixth group frame H6. The seventh lens group G7 is held in the seventh group frame H7. The eighth lens group G8 is held in the eighth group frame H8. The ninth lens group G9 is held in the ninth group frame H9.

[0164] A cam cylinder JC is rotatably positioned relative to the fixed cylinder JA on its outer circumference. The first group frame H1 is fixed to the object side of the fixed cylinder JA. The ninth group frame H9 is fixed to the image plane side of the fixed cylinder JA. Inside the fixed cylinder JA, in order from the object side, the second group frame H2, third group frame H3, fourth group frame H4, fifth group cylinder member U5, sixth group frame H6, seventh group cylinder member U7, and eighth group frame H8 are arranged. The fourth group frame H4 is fixed to the inside of the fixed cylinder JA. The fifth group frame H5 is positioned inside the fifth group cylinder member U5. The seventh group frame H7 is positioned inside the seventh group cylinder member U7. In addition, multiple guide bars extending along the optical axis are provided on the inner circumference of the fixed cylinder JA, and the guide grooves of the corresponding lens group frames and cylinder members are engaged with them.

[0165] Multiple cam grooves are formed in the cam cylinder JC, and the corresponding cam followers of the lens group frame and cylindrical member engage with them. Furthermore, on the outer circumference of the cam cylinder JC, as shown by the dashed line in Figure 2, a first operating ring K1 and a second operating ring K2 are rotatably provided relative to the fixed cylinder JA. The first operating ring K1 and the second operating ring K2 have the same configuration as the first operating ring K1 and the second operating ring K2 in the first embodiment, and a detailed explanation is omitted.

[0166] A fifth group drive unit (not shown) is provided on the fifth group barrel member U5. The fifth group drive unit drives the fifth group frame H5 in the optical axis direction. The fifth group drive unit can drive the fifth lens group G5 (first focusing lens group GF1) held in the fifth group frame H5 in the optical axis direction not only when focusing, but also when changing magnification from the first telephoto end state to the second telephoto end state. For example, the fifth group drive unit comprises a fifth group drive motor (not shown), a fifth group lead screw (not shown), and a fifth group rack (not shown). The fifth group drive motor is, for example, a stepping motor and is fixed to the fifth group barrel member U5. The fifth group lead screw is formed in an axial shape with a threaded portion extending in the optical axis direction and rotates in connection with the output shaft of the fifth group drive motor. The fifth group rack is screwed into the threaded portion of the fifth group lead screw and connected to the fifth group frame H5. Furthermore, the drive mechanism that drives the fifth group frame H5 in the optical axis direction can be modified as appropriate.

[0167] A seventh group drive unit (not shown) is provided on the seventh group barrel member U7. The seventh group drive unit drives the seventh group frame H7 in the optical axis direction. The seventh group drive unit can drive the seventh lens group G7 (second focusing lens group GF2), which is held in the seventh group frame H7, in the optical axis direction not only when focusing, but also when changing magnification from the first telephoto end state to the second telephoto end state. For example, the seventh group drive unit comprises a seventh group drive motor (not shown), a seventh group lead screw (not shown), and a seventh group rack (not shown). The seventh group drive motor is, for example, a stepping motor and is fixed to the seventh group barrel member U6. The seventh group lead screw is formed in an axial shape with a threaded portion extending in the optical axis direction and rotates in connection with the output shaft of the seventh group drive motor. The seventh group rack is screwed into the threaded portion of the seventh group lead screw and connected to the seventh group frame H7. Furthermore, the drive mechanism that drives the 7th group frame H7 in the optical axis direction can be modified as appropriate.

[0168] When changing magnification from the wide-angle end to the first telephoto end, the second group frame H2, the third group frame H3, the fifth group cylinder member U5, the sixth group frame H6, the seventh group cylinder member U7, and the eighth group frame H8 are driven in the optical axis direction by the rotation of the cam cylinder JC, which rotates in response to the rotation of the first operating ring K1. When changing magnification from the first telephoto end to the second telephoto end, or when focusing, the fifth group frame H5 is driven in the optical axis direction relative to the fifth group cylinder member U5 by a fifth group drive unit (not shown) provided on the fifth group cylinder member U5 in response to the rotation of the first operating ring K1 or the second operating ring K2. The seventh group frame H7 is also driven in the optical axis direction relative to the seventh group cylinder member U7 by a seventh group drive unit (not shown) provided on the seventh group cylinder member U7 in response to the rotation of the first operating ring K1 or the second operating ring K2.

[0169] Specifically, the second lens group G2, the third lens group G3, the sixth lens group G6, and the eighth lens group G8 are mechanically driven in the optical axis direction when the first operating ring K1 is rotated. In addition, the fifth lens group G5 and the seventh lens group G7 are mechanically and electrically (motor drive control) driven in the optical axis direction when the first operating ring K1 is rotated, and are electrically driven in the optical axis direction when the second operating ring K2 is rotated and focusing is instructed.

[0170] In this way, the second lens group G2, the third lens group G3, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 are driven in the optical axis direction when changing magnification from the wide-angle end state to the first telephoto end state. Furthermore, the fifth lens group G5 and the seventh lens group G7 are driven in the optical axis direction when changing magnification from the first telephoto end state to the second telephoto end state. In addition, the fifth lens group G5 and the seventh lens group G7 are driven in the optical axis direction when focusing. In this embodiment, the fifth lens group G5 and the seventh lens group G7 may be driven electrically in the optical axis direction, not limited to mechanically and electrically (motor drive control). The second lens group G2, the third lens group G3, the sixth lens group G6, and the eighth lens group G8 may be driven electrically in the optical axis direction, not limited to mechanically.

[0171] Table 3 below lists the specifications of the variable magnification optical system according to the third embodiment.

[0172] (Table 3) [Overall Specifications] Multiplication ratio (W→T1) = 2.727 Scale ratio (W→T2) = 3.794 MA=37.059 MB=15.653 MC=11.656 MG2=37.059 D23=47.981 MF1w=8.557 MF1t=15.653 MF2w=3.075 MF2t=11.656 WM T1 T2 f 71.500 135.000 195.000 271.250 FNO 2.880 2.880 2.880 4.008 ω 16.747 8.797 6.050 4.326 Y 21.700 21.700 21.700 21.700 TL 239.978 239.978 239.978 239.978 Bf 17.810 17.810 17.810 17.810 [Lens Specifications] Face number RD nd νd 1 109.659 2.800 1.92286 20.88 2 82.271 10.842 1.43700 95.10 3 -330.813 0.100 4 78.131 7.122 1.49782 82.57 5 307.441 (D5) 6 51.751 2.000 1.83481 42.73 7 28.594 8.150 8 -139.801 1.800 1.48749 70.32 9 65.177 0.100 10 43.822 4.076 1.92286 20.88 11 95.164 5.111 12 -50.633 1.800 1.48749 70.32 13 317.698 (D13) 14 188.326 3.760 1.83481 42.73 15 -250.346 0.100 16 47.444 5.947 1.49782 82.57 17 363.047 (D17) 18 ∞ 1.500 (Aperture S) 19 48.849 1.853 2.00100 29.12 20 29.628 6.234 1.49782 82.57 21 124.040 (D21) 22 -65.827 1.439 1.48749 70.32 23 70.507 1.322 24 447.716 1.418 1.83481 42.73 25 54.050 0.100 26 50.831 2.687 1.92286 20.88 27 87.988 (D27) 28 196.668 4.089 1.59319 67.90 29 -74.796 0.100 30 87.236 1.550 2.00100 29.12 31 41.918 5.718 1.49782 82.57 32 -134.651 (D32) 33 42.183 5.228 1.59319 67.90 34 267.553 (D34) 35* 159.982 1.600 1.85108 40.12 36 34.158 3.067 37 164.439 3.840 1.80518 25.45 38 -93.492 (D38) 39* -24.902 1.551 1.85108 40.12 40 -94.419 0.100 41 66.664 6.668 1.61293 36.95 42 -101.262 Bf [Aspherical data] Page 35 κ=1.000,A4=4.10175E-06,A6=1.87631E-10,A8=1.07919E-12,A10=0.00000E+00 Page 39 κ=1.000,A4=1.01290E-06,A6=-7.68488E-09,A8=3.60877E-11,A10=-8.29554E-14 [Variable interval data] Infinity focus state WM T1 T2 Focal length 71.500 135.000 195.000 271.250 D0 ∞ ∞ ∞ ∞ D5 1.500 23.225 38.559 38.559 D13 49.481 24.746 1.500 1.500 D17 2.008 5.018 12.929 12.929 D21 12.289 17.413 3.733 19.387 D27 9.729 6.501 17.742 2.088 D32 12.904 11.199 16.523 28.180 D34 18.149 18.464 13.189 1.533 D38 12.336 11.828 14.222 14.222 Bf 17.810 17.810 17.810 17.810 Close-range focus WM T1 T2 Magnification -0.199 -0.130 -0.165 -0.087 D0 250.000 700.000 900.000 3000.000 D5 1.500 23.225 38.559 38.559 D13 49.481 24.746 1.500 1.500 D17 2.008 5.018 12.929 12.929 D21 8.548 7.647 3.319 19.387 D27 13.470 16.268 18.156 2.088 D32 5.534 1.883 1.473 15.192 D34 25.519 27.780 28.240 14.520 D38 12.336 11.828 14.222 14.222 Bf 17.810 17.810 17.810 17.810 [Lens group data] Group Starting surface Focal length G1 1 117.117 G2 6 -39.745 G3 14 59.286 G4 19 -23380.000 G5 22 -48.470 G6 28 71.329 G7 33 83.699 G8 35 -201.391 G9 39 -113.675

[0173] FIG. 13 is a diagram of various aberrations at infinity focus in the wide-angle end state of the zoom optical system according to the third embodiment. FIG. 14 is a diagram of various aberrations at infinity focus in the first telephoto end state of the zoom optical system according to the third embodiment. FIG. 15 is a diagram of various aberrations at infinity focus in the second telephoto end state of the zoom optical system according to the third embodiment. From each aberration diagram, it can be seen that the zoom optical system according to the third embodiment has excellent aberration correction and excellent imaging performance from the wide-angle end state to the first telephoto end state and from the first telephoto end state to the second telephoto end state.

[0174] Next, the table of [Conditional Expression Corresponding Values] is shown below. This table summarizes the values ​​corresponding to each conditional expression (1) to (17) for all examples (Examples 1 to 3). Condition (1) 0.10 <MB / MA<2.00 Conditional expression (2) ft1 / ft2<0.95 Condition (3) 0.75 <MG2 / (-f2)<1.30 Condition (4) 0.01 <Bft2 / ft2<0.30 Condition (5) 0.75 <D23 / (-f2)<1.40 Condition (6) 0.45 <D23 / f3<1.00 Conditional expression (7) 0 <MF1w / MF1t<1.00 Condition (8) 0.05 <MF2w / MF2t<10.00 Condition (9) 0.01 <MC / MB<2.00 Condition (10) 0.10 <Bft2 / MB<5.00 Conditional expression (11) 0.05<(-f2) / f1<1.00 Condition (12) 0.01 <Bfw / fw<0.50 Condition (13) 2.00 <TLw / fw<6.00 Conditional expression (14) 0.01<(-f2) / f3<2.00 Condition (15) 1.80 <f1 / f3<2.50 Conditional expression (16) 0.01<|fr1 / fr|<5.00 Condition (17) 0.10 <f2 / fr1<0.75

[0175] [Conditional Expression Corresponding Values] (Examples 1-3) Conditional expression First example Second example Third example (1) 0.407 0.486 0.422 (2) 0.688 0.688 0.719 (3) 0.881 1.006 0.932 (4) 0.040 0.061 0.066 (5) 0.881 1.006 1.207 (6) 0.693 0.653 0.809 (7) 0.0043 0.3066 0.5467 (8) 2.366 5.285 0.264 (9) 0.051 0.083 0.745 (10) 0.721 0.933 1.138 (11) 0.348 0.319 0.339 (12) 0.164 0.249 0.249 (13) 3.495 3.495 3.356 (14) 0.787 0.649 0.670 (15) 2.261 2.031 1.975 (16) 0.084 0.774 1.772 (17) 0.639 0.371 0.197

[0176] According to the above embodiments, it is possible to realize a variable magnification optical system that is compact yet bright and has good optical performance.

[0177] The above embodiments illustrate specific examples of the present invention, and the present invention is not limited to these.

[0178] The following elements can be appropriately adopted in each embodiment, provided that they do not impair the optical performance of the variable magnification optical system.

[0179] While examples of the variable magnification optical system in each embodiment show configurations with 8 and 9 groups, this application is not limited to these, and variable magnification optical systems with other group configurations (e.g., 10 groups, 11 groups, 12 groups, etc.) can also be constructed. For example, a configuration in which a lens or lens group is added to the object side or the image plane side of the variable magnification optical system in each embodiment is also acceptable. Alternatively, for example, a configuration in which a lens or lens group is added to the object side or the image plane side of the rear group in the variable magnification optical system in each embodiment is also acceptable. Note that a lens group refers to a portion having at least one lens separated by an air gap that changes during magnification.

[0180] In the variable magnification optical system of each embodiment, the focusing lens group may be not limited to the first to third focusing lens groups described above, but may also be a single or multiple lens groups, or a partial lens group, moved along the optical axis to focus from an object at infinity to an object at close range. The focusing lens group can also be applied to autofocus and is suitable for motor drive (using an ultrasonic motor, etc.) for autofocus.

[0181] A lens group or partial lens group may be moved so that it has a component perpendicular to the optical axis, or rotated (oscillated) in the in-plane direction including the optical axis, to correct image blur caused by camera shake.

[0182] The lens surface may be formed as a spherical, flat, or aspherical surface. A spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment, preventing degradation of optical performance due to processing and assembly errors. It is also preferable because it minimizes degradation of image rendering performance even if the image plane is misaligned.

[0183] If the lens surface is aspherical, it can be an aspherical surface created by grinding, a glass molded aspherical surface formed from glass using a mold, or a composite aspherical surface formed by creating an aspherical shape from resin on the surface of glass. Furthermore, the lens surface may also be a diffractive surface, and the lens may be a refractive index distributed lens (GRIN lens) or a plastic lens.

[0184] The aperture diaphragm is preferably positioned between the third and fourth lens groups, but its function may be substituted by the lens frame instead of providing a separate aperture diaphragm component.

[0185] Each lens surface may be coated with an anti-reflective coating that has high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high contrast optical performance. [Explanation of symbols]

[0186] G1 First lens group G2 Second lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group, G8 8th lens group G9 9th lens group I Image plane S Aperture diaphragm

Claims

1. It consists of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group having at least five lens groups, all arranged in order from the object side along the optical axis. When changing magnification from the wide-angle end to the first telephoto end, the spacing between adjacent lens groups changes, the first lens group is fixed relative to the image plane, and the second lens group moves along the optical axis. When changing magnification from the first telephoto end state to the second telephoto end state, the first lens group and the second lens group are fixed with respect to the image plane, and at least two of the at least five lens groups of the rear group move along the optical axis. A variable magnification optical system that satisfies the following conditions. 0.75<MG2 / (-f2)<1.30 ft1 / ft2<0.95 However, f2: focal length of the second lens group MG2: Amount of movement of the second lens group when changing magnification from the wide-angle end to the first telephoto end. ft1: Focal length of the variable magnification optical system in the first telephoto end state. ft2: Focal length of the variable magnification optical system in the second telephoto end state.

2. The aforementioned rear group of at least five lens groups includes at least two focusing lens groups that move along the optical axis when focusing, The variable magnification optical system according to claim 1, wherein at least two focusing lens groups move along the optical axis when changing magnification from a first telephoto end state to a second telephoto end state.

3. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.01<Bft2 / ft2<0.30 However, Bft2: Back focus of the variable magnification optical system in the second telephoto end state

4. The aforementioned rear group includes the final lens group, which is positioned closest to the image plane. The variable magnification optical system according to claim 1, wherein the final lens group is fixed to the image plane when changing magnification from the wide-angle end state to the first telephoto end state and when changing magnification from the first telephoto end state to the second telephoto end state.

5. The variable magnification optical system according to claim 1, wherein the third lens group is fixed with respect to the image plane when changing magnification from a first telephoto end state to a second telephoto end state.

6. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.75<D23 / (-f2)<1.40 However, f2: focal length of the second lens group D23: The amount of change in the distance between the second lens group and the third lens group on the optical axis when changing magnification from the wide-angle end state to the first telephoto end state.

7. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.45<D23 / f3<1.00 However, f3: focal length of the third lens group D23: The amount of change in the distance between the second lens group and the third lens group on the optical axis when changing magnification from the wide-angle end state to the first telephoto end state.

8. The aforementioned rear group of at least five lens groups includes at least two focusing lens groups that move along the optical axis when focusing, A variable magnification optical system according to claim 1 that satisfies the following condition. 0<MF1w / MF1t<1.00 However, MF1w: The amount of movement of the first focusing lens group, which is positioned closest to the object among the at least two focusing lens groups, when changing magnification from the wide-angle end state to the first telephoto end state. MF1t: Amount of movement of the first focusing lens group when changing magnification from the first telephoto end state to the second telephoto end state.

9. The aforementioned rear group of at least five lens groups includes at least two focusing lens groups that move along the optical axis when focusing, A variable magnification optical system according to claim 1 that satisfies the following condition. 0.05<MF2w / MF2t<10.00 However, MF2w: The amount of movement of the second focusing lens group, which is the second from the object side among the at least two focusing lens groups, when changing magnification from the wide-angle end state to the first telephoto end state. MF2t: Amount of movement of the second focusing lens group when changing magnification from the first telephoto end state to the second telephoto end state.

10. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.01<MC / MB<2.00 However, MB: The amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state. MC: The amount of movement of the lens group with the smallest movement when changing magnification from the first telephoto end state to the second telephoto end state.

11. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.10<Bft2 / MB<5.00 However, MB: The amount of movement of the lens group with the largest movement when changing magnification from the first telephoto end state to the second telephoto end state. Bft2: Back focus of the variable magnification optical system in the second telephoto end state.

12. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.05<(-f2) / f1<1.050 However, f1: focal length of the first lens group f2: Focal length of the second lens group

13. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.01<Bfw / fw<0.50 However, fw: focal length of the variable magnification optical system at the wide-angle end. Bfw: Back focus of the variable magnification optical system at the wide-angle end.

14. A variable magnification optical system according to claim 1 that satisfies the following condition. 2.00<TLw / fw<6.00 However, fw: focal length of the variable magnification optical system at the wide-angle end. TLw: Total length of the variable magnification optical system at the wide-angle end.

15. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.01<(-f2) / f3<2.00 However, f2: focal length of the second lens group f3: Focal length of the third lens group

16. A variable magnification optical system according to claim 1 that satisfies the following condition. 1.80<f1 / f3<2.50 However, f1: focal length of the first lens group f3: Focal length of the third lens group

17. The aforementioned rear group includes the final lens group, which is positioned closest to the image plane. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.01<|fr1 / fr|<5.00 However, fr: focal length of the final lens group fr1: The focal length of the lens group arranged in the rear group, adjacent to the object side of the final lens group.

18. The aforementioned rear group includes the final lens group, which is positioned closest to the image plane. A variable magnification optical system according to claim 1 that satisfies the following condition. 0.10<f2 / fr1<0.75 However, f2: focal length of the second lens group fr1: The focal length of the lens group arranged in the rear group, adjacent to the object side of the final lens group.

19. An optical instrument comprising the variable magnification optical system described in claim 1.

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