Zoom imaging optical system

Abstract

To provide a zoom imaging optical system which is reduced in size and weight, and yet suppresses magnification chromatic aberration and axial chromatic aberration while zooming, features high-speed focusing with minimized performance deterioration in a short distance range, and offers good optical performance over an entire zoom range from infinity to a short distance.SOLUTION: A zoom imaging optical system disclosed herein consists of a positive first lens group G1, a positive second lens group G2, a negative third lens group G3, a first intermediate group GM1 consisting of one or more lens groups and an aperture stop, a second intermediate group GM2, and a succeeding group GR consisting of one or more lens groups, arranged in order from the object side, and is configured to change inter-lens group distances while zooming or focusing. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side while the second lens group G2 is stationary, increasing the distance between the first lens group G1 and the second lens group G2 and reducing the distance between the second lens group G2 and the third lens group G3. At least the second intermediate group GM2 moves while focusing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a variable magnification imaging optical system suitable for an imaging optical system used in an imaging device such as a digital camera or a video camera. [Background technology]

[0002] In recent years, as digital cameras, video cameras, and other devices have become more mirrorless, high-performance cameras have begun to be installed in smartphones and mobile data terminals. As a result, there is a growing demand for super-telephoto zoom lenses for digital cameras and video cameras in order to differentiate them from these mobile devices.

[0003] Furthermore, in recent digital cameras and video cameras, the number of pixels in the image pickup elements has increased, and the demand for higher performance in the image pickup optical system has increased.

[0004] Patent Documents 1 to 4 describe examples of variable magnification imaging optical systems in which the half angle of view at the telephoto end is approximately 3 degrees or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-167749 A [Patent Document 2] JP 2016-080825 A [Patent Document 3] JP 2019-020450 A [Patent Document 4] JP 2020-052338 A Summary of the Invention [Problem to be solved by the invention]

[0006] In an ultra-telephoto zoom lens with a narrow angle of view at the telephoto end, it is necessary to achieve three things at the same time: a large magnification ratio is required to improve usability as a zoom lens, compactness is required to improve portability, and imaging performance is required.

[0007] In order to achieve a large zoom ratio, it is common to position the lens group with positive refractive power closest to the object and then move it toward the object by varying the magnification to maximize the telephoto ratio at the telephoto end (the total optical length divided by the focal length) and improve imaging performance when using telephoto lenses.

[0008] Furthermore, in telephoto lenses, aberrations occurring in the lens group of the converging system arranged on the object side are magnified by the lens group behind it. With a prime lens, imaging performance can be improved by simply suppressing the aberrations occurring in the converging system on the object side based on this relationship, but with a zoom lens, various aberrations fluctuate due to changes in the power arrangement caused by magnification change, so this cannot be simplified like with a prime lens. Magnification chromatic aberration, which is particularly problematic with super telephoto lenses with a narrow angle of view, changes in the direction in which it occurs as the magnification changes, so in order to reduce the size of the optical system while suppressing the occurrence of magnification chromatic aberration over the entire zoom range, it is important to select optical materials that correspond to the change in power arrangement caused by magnification change.

[0009] Furthermore, when attempting to increase the magnification in the telephoto range, close-up imaging performance deteriorates with a single focus group, so a method of improving close-up imaging performance by using multiple focus groups is known.

[0010] The optical system described in Patent Document 1 is an example of an ultra-telephoto zoom lens with a fixed overall length, in which various aberrations are suppressed throughout the entire zoom range and imaging performance is high; however, if one were to attempt to increase the zoom ratio while maintaining imaging performance with such a fixed-length type optical system, the optical system would become significantly larger, which is not desirable.

[0011] The optical system described in Patent Document 2 is an example of a super telephoto zoom lens with a variable length type in which the first group extends, but the back focus (the distance from the final lens to the image plane) is large relative to the total optical length, and considering the short flange back caused by the recent trend toward mirrorless cameras, it is insufficient in terms of compactness of the optical system. In addition, there is a large fluctuation in lateral chromatic aberration from the wide-angle end to the telephoto end, and correction is insufficient.

[0012] The optical system described in Patent Document 3 is an example of an ultra-telephoto zoom lens that supports a short flange back, but there is a large variation in lateral chromatic aberration from the wide-angle end to the telephoto end, and correction of this aberration is insufficient, and suppression of the overall optical length at the wide-angle end is also insufficient.

[0013] Patent Document 4 includes an example of an ultra-telephoto zoom lens with multiple focus groups, which maintains good performance even at a magnification exceeding 0.2x at the telephoto end. However, the zoom ratio is small at around 2x, and the optical system is not sufficiently compact.

[0014] The present invention has been made in consideration of these problems, and has an object to provide a variable magnification imaging optical system that is compact and lightweight, suppresses lateral chromatic aberration and axial chromatic aberration during magnification change, has high-speed focusing and focusing that suppresses performance degradation at close distances, and has good optical performance from infinity to close ranges over the entire zoom range. [Means for solving the problem]

[0015] In order to achieve the above object, a variable magnification imaging optical system includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of one or more lens groups and including an aperture stop S, a second intermediate group GM2, and a subsequent group GR consisting of one or more lens groups, wherein a distance between adjacent lens groups changes during magnification or focusing, and when magnifying from a wide-angle end to a telephoto end, the first lens group G1 moves toward the object side and the second lens group G2 is fixed with respect to an image plane, a distance between the first lens group G1 and the second lens group G2 increases and a distance between the second lens group G2 and the third lens group G3 decreases, and when focusing from an object at infinity to an object at a close distance, at least the second intermediate group GM2 moves along the optical axis.

[0016] In order to achieve the above object, a variable magnification imaging optical system includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of one or more lens groups and including an aperture stop S, a second intermediate group GM2, and a subsequent group GR consisting of one or more lens groups, wherein a distance between adjacent lens groups changes during magnification or focusing, and when varying magnification from a wide-angle end to a telephoto end, the first lens group G1 moves toward the object side and the second lens group G2 moves toward the image side, the distance between the first lens group G1 and the second lens group G2 increases, and the third lens group G3 moves so that the distance between it and the second lens group G2 decreases, and when focusing from an object at infinity to an object at a close distance, at least the second intermediate group GM2 moves along the optical axis. Effect of the Invention

[0017] According to the present invention, a variable magnification imaging optical system is provided which is compact and lightweight, suppresses lateral chromatic aberration and axial chromatic aberration during magnification change, has high speed focusing and focusing with reduced performance degradation at close distances, and has good optical performance from infinity to close ranges over the entire zoom range. [Brief description of the drawings]

[0018] [Figure 1] 1 is a lens configuration diagram of a variable magnification image forming optical system according to a first embodiment of the present invention when focusing on an object at infinity at a wide-angle end. [Diagram 2] 2 is a longitudinal aberration diagram of the variable magnification image forming optical system according to the first embodiment of the present invention when focused on an object at infinity at the wide-angle end. FIG. [Diagram 3] 1 is a longitudinal aberration diagram of a variable magnification image forming optical system according to Example 1 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 4] 1 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 1 of the present invention when focused on an object at infinity at the telephoto end. [Diagram 5] 4A to 4C are lateral aberration diagrams illustrating the variable magnification image forming optical system according to the first embodiment of the present invention when focused on an object at infinity at the wide-angle end. [Figure 6] 1 is a lateral aberration diagram of a variable magnification image forming optical system according to Example 1 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 7] 3A to 3C are lateral aberration diagrams illustrating the variable magnification image forming optical system according to the first embodiment of the present invention when focused on an object at infinity at the telephoto end. [Figure 8] 4A to 4C are lateral aberration diagrams of the variable magnification image forming optical system according to the first embodiment of the present invention when focused on an object distance of 2.8 m at the wide-angle end. [Figure 9] FIG. 2 is a lateral aberration diagram of the variable magnification image forming optical system according to the first embodiment of the present invention when the object distance is 2.8 m and the intermediate focal length is focused. [Figure 10] 4A to 4C are lateral aberration diagrams of the variable magnification image forming optical system according to the first embodiment of the present invention when focused on an object distance of 2.8 m at the telephoto end. [Figure 11] FIG. 11 is a lens configuration diagram of a variable magnification image forming optical system according to a second embodiment of the present invention when focused on infinity at a wide-angle end. [Figure 12] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 2 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 13] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 2 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 14] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 2 of the present invention when focused on an object at infinity at the telephoto end. [Figure 15] 10A to 10C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 2 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 16] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 2 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 17] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 2 of the present invention when focused on an object at infinity at the telephoto end. [Figure 18] 10A to 10C are lateral aberration diagrams of the variable magnification image forming optical system according to Example 2 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 19] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 2 of the present invention when the optical system has an intermediate focal length and is focused on an object distance of 2.5 m. [Figure 20] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 2 of the present invention when focused on an object distance of 2.5 m at the telephoto end. [Figure 21] FIG. 11 is a lens configuration diagram of a variable magnification image forming optical system according to a third embodiment of the present invention when focusing on an object at infinity at a wide-angle end. [Figure 22] 11 is a longitudinal aberration diagram of a variable magnification image forming optical system according to Example 3 of the present invention when focused on an object at infinity at the wide-angle end. FIG. [Figure 23] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 3 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 24] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 3 of the present invention when focused on an object at infinity at the telephoto end. [Diagram 25] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 3 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 26] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 3 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 27] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 3 of the present invention when focused on an object at infinity at the telephoto end. [Figure 28] 11A to 11C are lateral aberration diagrams of the variable magnification image forming optical system according to Example 3 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 29] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 3 of the present invention when the object distance is 2.5 m and the intermediate focal length is focused. [Diagram 30] 11A to 11C are lateral aberration diagrams of the variable magnification image forming optical system according to Example 3 of the present invention when focused on an object distance of 2.4 m at the telephoto end. [Diagram 31] FIG. 11 is a lens configuration diagram of a variable magnification image forming optical system according to Example 4 of the present invention when focusing on an object at infinity at the wide-angle end. [Diagram 32] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 4 of the present invention when focused on an object at infinity at the wide-angle end. [Diagram 33] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 4 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Diagram 34] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 4 of the present invention when focused on an object at infinity at the telephoto end. [Diagram 35] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 4 of the present invention when focused on an object at infinity at the wide-angle end. [Diagram 36] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 4 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 37] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 4 of the present invention when focused on an object at infinity at the telephoto end. [Figure 38] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 4 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 39] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 4 of the present invention, when the object distance is 2.5 m and the intermediate focal length is focused. [Diagram 40] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 4 of the present invention when focused on an object distance of 2.4 m at the telephoto end. [Diagram 41] FIG. 11 is a lens configuration diagram of a variable magnification image forming optical system according to a fifth embodiment of the present invention when focusing on an object at infinity at the wide-angle end. [Diagram 42] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 5 of the present invention when focused on an object at infinity at the wide-angle end. [Diagram 43] FIG. 11 is a longitudinal aberration diagram of a variable magnification image forming optical system according to Example 5 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Diagram 44] FIG. 11 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 5 of the present invention when focused on an object at infinity at the telephoto end. [Diagram 45] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 5 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 46] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 5 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 47] 11A to 11C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 5 of the present invention when focused on an object at infinity at the telephoto end. [Figure 48] 11A to 11C are lateral aberration diagrams illustrating the variable magnification image forming optical system according to Example 5 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 49] FIG. 11 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 5 of the present invention, when the object distance is 2.5 m and the intermediate focal length is focused. [Figure 50] 11A to 11C are lateral aberration diagrams of the variable magnification image forming optical system according to Example 5 of the present invention when focused on an object distance of 2.4 m at the telephoto end. [Figure 51] FIG. 13 is a lens configuration diagram of a variable magnification image forming optical system according to Example 6 of the present invention when focusing on an object at infinity at the wide-angle end. [Figure 52] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 6 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 53] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 6 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 54] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 6 of the present invention when focused on an object at infinity at the telephoto end. [Figure 55] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 6 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 56] FIG. 13 is a lateral aberration diagram of Example 6 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 57] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 6 of the present invention when focused on an object at infinity at the telephoto end. [Figure 58] 13A to 13C are lateral aberration diagrams of the variable magnification image forming optical system according to Example 6 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 59] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 6 of the present invention when the object distance is 2.5 m and the intermediate focal length is focused. [Figure 60] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 6 of the present invention when focused on an object distance of 2.5 m at the telephoto end. [Figure 61] FIG. 13 is a lens configuration diagram of a variable magnification image forming optical system according to Example 7 of the present invention when focusing on infinity at the wide-angle end. [Figure 62] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 63] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 64] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when focused on an object at infinity at the telephoto end. [Figure 65] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 66] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 67] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when focused on an object at infinity at the telephoto end. [Figure 68] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when focused on an object distance of 3.2 m at the wide-angle end. [Figure 69] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when the object distance is 3.2 m and the intermediate focal length is focused. [Figure 70] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 7 of the present invention when focused on an object distance of 3.2 m at the telephoto end. [Figure 71] FIG. 13 is a lens configuration diagram of a variable magnification image forming optical system according to Example 8 of the present invention when focusing on an object at infinity at the wide-angle end. [Figure 72] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 73] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention when the optical system is focused on an object at infinity at an intermediate focal length. [Figure 74] FIG. 13 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention when focused on an object at infinity at the telephoto end. [Figure 75] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 76] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 77] FIG. 13 is a lateral aberration diagram of Example 8 of the variable magnification image forming optical system of the present invention when focused on an object at infinity at the telephoto end. [Figure 78] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 79] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention, when the object distance is 2.5 m and the intermediate focal length is focused. [Figure 80] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 8 of the present invention when focused on an object distance of 2.5 m at the telephoto end. [Figure 81] FIG. 13 is a lens configuration diagram of a variable magnification image forming optical system according to Example 9 of the present invention when focusing on infinity at the wide-angle end. [Figure 82] 13 is a longitudinal aberration diagram of Example 9 of the variable magnification image forming optical system of the present invention when focused on an object at infinity at the wide-angle end. [Figure 83] FIG. 13 is a longitudinal aberration diagram of Example 9 of the variable magnification image forming optical system of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 84] 13 is a longitudinal aberration diagram of Example 9 of the variable magnification image forming optical system of the present invention when focused on an object at infinity at the telephoto end. [Figure 85] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 9 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 86] FIG. 13 is a lateral aberration diagram of Example 9 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 87] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 9 of the present invention when focused on an object at infinity at the telephoto end. [Figure 88] 13A to 13C are lateral aberration diagrams for Example 9 of the variable magnification image forming optical system of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 89] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 9 of the present invention, when the object distance is 2.5 m and the intermediate focal length is focused. [Figure 90] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 9 of the present invention when focused on an object distance of 2.5 m at a telephoto end. [Figure 91] FIG. 13 is a lens configuration diagram of a variable magnification image forming optical system according to a tenth embodiment of the present invention when focusing on an object at infinity at the wide-angle end. [Figure 92] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 10 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 93] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 10 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 94] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 10 of the present invention when focused on an object at infinity at the telephoto end. [Figure 95] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to a tenth embodiment of the present invention when focused on an object at infinity at the wide-angle end. [Figure 96] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 10 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 97] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 10 of the present invention when focused on an object at infinity at the telephoto end. [Figure 98] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 10 of the present invention when focused on an object distance of 3.2 m at the wide-angle end. [Figure 99] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 10 of the present invention, when the intermediate focal length is focused on an object distance of 3.2 m. [Figure 100] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 10 of the present invention when focused on an object distance of 3.2 m at the telephoto end. [Figure 101] FIG. 13 is a lens configuration diagram of an eleventh embodiment of a variable magnification image forming optical system according to the present invention when focusing on an object at infinity at the wide-angle end. [Figure 102] FIG. 15 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 103] FIG. 16 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 104] FIG. 15 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention when focused on an object at infinity at the telephoto end. [Figure 105]13A to 13C are lateral aberration diagrams illustrating the variable magnification image forming optical system according to Example 11 of the present invention when focused on an object at infinity at the wide-angle end. [Fig. 106] FIG. 13 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 107] FIG. 15 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention when focused on an object at infinity at the telephoto end. [Figure 108] FIG. 15 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Fig. 109] FIG. 16 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention, when the object distance is 2.5 m and the intermediate focal length is focused. [Figure 100] FIG. 15 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 11 of the present invention when focused on an object distance of 2.5 m at the telephoto end. [Figure 111] FIG. 23 is a lens configuration diagram of a variable magnification image forming optical system according to Example 12 of the present invention when focusing on an object at infinity at the wide-angle end. [Figure 112] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 113] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when the intermediate focal length is focused on an object at infinity. [Fig. 114] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when focused on an object at infinity at the telephoto end. [Figure 115] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when focused on an object at infinity at the wide-angle end. [Fig. 116] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 117] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when focused on an object at infinity at the telephoto end. [Fig. 118] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when focused on an object distance of 3.2 m at the wide-angle end. [Figure 119] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when the intermediate focal length is focused on an object distance of 3.2 m. [Figure 120] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 12 of the present invention when focused on an object distance of 3.2 m at the telephoto end. [Figure 121] FIG. 23 is a lens configuration diagram of a variable magnification image forming optical system according to Example 13 of the present invention when focusing on an object at infinity at the wide-angle end. [Figure 122] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 123] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 124] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention when focused on an object at infinity at the telephoto end. [Fig. 125] 13A to 13C are lateral aberration diagrams illustrating a variable magnification image forming optical system according to Example 13 of the present invention when focused on an object at infinity at the wide-angle end. [Fig. 126] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 127] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention when focused on an object at infinity at the telephoto end. [Figure 128] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention when focused on an object distance of 2.5 m at the wide-angle end. [Figure 129] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention, when the object distance is 2.5 m and the intermediate focal length is focused. [Fig. 130] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 13 of the present invention when focused on an object distance of 2.5 m at the telephoto end. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A variable magnification imaging optical system according to an embodiment of the present invention will be described below. Note that the following description of the embodiment is an example of the optical system of the present invention, and the present invention is not limited to this embodiment without departing from the gist of the present invention. In addition, the object side will be described as the front and the image side as the rear.

[0020] In the following description of the embodiment, the refractive indices of the materials for the g-line (wavelength 435.8 nm), F-line (486.1 nm), d-line (587.6 nm), and C-line (656.3 nm) are Ng, NF, Nd, and NC, respectively. The Abbe number νd, partial dispersion ratio PgF, and anomalous partial dispersion ΔPgF are expressed as follows: νd = (Nd-1) / (NF-NC) PgF = (Ng-NF) / (NF-NC) ΔPgF = PgF-0.64833+0.00180×νd It is expressed as:

[0021] In this application, when counting the number of lenses, unless otherwise specified, a single lens is counted as one lens, and in the case of a cemented lens, each of the single lenses constituting the cemented lens is counted as one lens. For example, a cemented lens of a convex lens and a concave lens is counted as two lenses.

[0022] In this application, the lens groups are defined as surfaces whose distance on the optical axis changes due to magnification or focusing. Therefore, in cases where the aperture diaphragm S moves independently due to magnification or focusing, the aperture diaphragm S is treated as one lens group.

[0023] In this application, there are descriptions of ray heights, such as axial marginal ray height and off-axial chief ray height, but since these basically mean the distance from the optical axis, there is no concept of positive or negative, and the optical axis is treated as 0 and the direction away from it is treated as positive. However, with regard to the off-axial chief ray in conditional expressions (4) and (5), a positive or negative relationship arises since it deals with the relationship between the image height of the off-axial chief ray and the height of the off-axial chief ray passing through the second lens group G2.

[0024] In an ultra-telephoto zoom lens like the one in the present invention, suppressing chromatic aberration is an essential element for improving performance. There are two types of chromatic aberration: axial chromatic aberration and lateral chromatic aberration, and in order to suppress both of these across the entire zoom range, it is important to select an appropriate glass material in accordance with changes in the power distribution.

[0025] In general, the lateral chromatic aberration of an optical system composed of thin lenses is given as the sum of each lens by the following (Reference Formula 1), and can be thought of as follows:

[0026] When a lens with positive refractive power is placed on the object side of the aperture, the peripheral light flux passing through the lens passes through the quadrant opposite the image formation position, and in the case of general optical glass, due to the dispersion characteristics, the longer the wavelength, the lower the image height will be, and the C-line will be observed as lateral chromatic aberration in the under direction. Similarly, when a lens with negative refractive power is placed on the object side of the aperture, the opposite phenomenon to the above occurs. Furthermore, when a lens is placed on the image side of the aperture, the peripheral light flux passing through the lens and the image formation position pass through the same quadrant, so the opposite phenomenon to when a lens is placed on the object side of the aperture occurs. (Reference formula 1)Σ(h·hb·φ / ν) h: Height of the marginal ray on the axis hb: Off-axis chief ray height φ: Refractive power ν: Abbe number An axial marginal ray is defined as a ray included in an axial light beam that passes through the aperture at the maximum height from the optical axis, and a principal ray is defined as a ray that passes through the point where the aperture surface and the optical axis intersect.

[0027] Similarly, the axial chromatic aberration of an optical system composed of thin lenses is given as the sum of each lens by the following (Reference Formula 2), and can be thought of as follows: (Reference formula 2)Σ(h·h·φ / ν) h: Height of the marginal ray on the axis φ: Refractive power ν: Abbe number The axial marginal ray is defined as a ray that passes through the aperture at the maximum height from the optical axis among the rays contained in the axial light beam. Regarding Reference Formula 2, when attention is paid to the axial marginal ray height, the amount of axial chromatic aberration generated is greater for lenses through which axial marginal rays pass at a higher position relative to the effective diameter, and the amount of axial chromatic aberration generated is smaller for lenses through which axial marginal rays pass at a lower position. Therefore, in order to suppress axial chromatic aberration and lateral chromatic aberration over the entire zoom range, it is necessary to select glass materials appropriately in accordance with changes in the ray height of axial marginal rays and off-axial chief rays during zooming.

[0028] In a variable magnification imaging optical system such as that of the present invention in which the first lens group G1 has positive refractive power, and which extends significantly when changing magnification from the wide-angle end to the telephoto end, widening the distance from the aperture stop S, chromatic aberration of magnification often occurs with the C-line over at the wide-angle end and the C-line under at the telephoto end, and fluctuates with magnification. For this reason, if the g-line and C-line are collected together and there is a large difference in imaging magnification with other wavelengths, undesirable color bleeding such as reddish purple appears on the subject's outline as a secondary spectrum.

[0029] This phenomenon occurs because, when the magnification is changed from the wide-angle side to the telephoto side, the first lens group G1 moves out, widening the distance from the aperture diaphragm S, and the lens groups from the second lens group G2 onwards change in power arrangement as they move closer to the aperture diaphragm S, causing not only a change in the lateral chromatic aberration that occurs in the first lens group G1 but also a significant change in the correction effect of the lateral chromatic aberration in the lens groups from the second lens group G2 onwards. The greater the distance from the aperture diaphragm S, the more the off-axis chief ray passes through a higher position further from the optical axis, and as shown in (Reference Equation 1), the change in ray height causes a change in lateral chromatic aberration.

[0030] In addition, it is effective to appropriately arrange glass materials having anomalous dispersion in accordance with the change in the correction effect of lateral chromatic aberration caused by magnification change in order to correct the secondary spectrum. For example, in a case where g-line and C-line are collected and secondary spectrum between the d-line becomes a problem, if the d-line and C-line are collected forcibly, the g-line will be undercorrected, but if a glass material having anomalous dispersion is used, it is possible to make up for the undercorrection of the g-line, and as a result, it is possible to reduce the secondary spectrum. Hereinafter, an embodiment of the present invention in which secondary spectrum is suppressed and lateral chromatic aberration is effectively corrected over the entire zoom range will be described with a focus on the correction of the g-line.

[0031] As can be seen from the numerical examples and the configuration diagrams of each example, the variable magnification image-forming optical system of the present invention comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of one or more lens groups and including an aperture stop S, a second intermediate group GM2, and a subsequent group GR consisting of one or more lens groups. During variable magnification or focusing, the distance between adjacent lens groups changes, and when varying magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side and the second lens group G2 is fixed with respect to the image plane or moves toward the image side, the distance between the first lens group G1 and the second lens group G2 increases and the distance between the second lens group G2 and the third lens group G3 decreases. During focusing from an object at infinity to an object at a close distance, the second intermediate group GM2 moves along the optical axis.

[0032] The first lens group G1 has positive refractive power, the second lens group G2 has positive refractive power, and the third lens group G3 has negative refractive power. When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 remains fixed with respect to the image plane or moves toward the image side, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases, thereby achieving the main magnification effect of the variable magnification imaging optical system.

[0033] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2, which has positive refractive power, is fixed relative to the image plane or moves toward the image side, and the lens group including the aperture stop S moves toward the object side. As a result, the distance to the aperture stop S becomes smaller when changing magnification from the wide-angle end to the telephoto end, and the off-axis chief ray that passes through a high position at the wide-angle end changes to pass through a lower position at the telephoto end, and the correction effect of the second lens group G2 for the lateral chromatic aberration is greater at the wide-angle end and smaller at the telephoto end.

[0034] On the other hand, as the first lens group G1 moves toward the object side on the telephoto side and the distance between it and the second lens group G2 increases, the height of the axial marginal ray when focusing at infinity is lower for the second lens group G2 than for the first lens group G1, and in the second lens group G2, the height of the axial marginal ray at the telephoto end changes to be lower than the height of the off-axial chief ray at the maximum angle of view at the wide-angle end.

[0035] Furthermore, if a glass material with positive anomalous dispersion is used for the concave lens and a glass material with negative anomalous dispersion for the convex lens in the second lens group G2, it becomes possible to correct for the g-line in the under direction on the wide-angle side, making it easier to correct lateral chromatic aberration.

[0036] The first intermediate group GM1, which is made up of one or more lens groups and includes an aperture stop S, has the effect of converging the light beam diverged by the third lens group G3 and has the effect of controlling the height of the light rays entering the second intermediate group GM2 to an appropriate height. This contributes to reducing the weight of the second intermediate group GM2 and also plays a role in compensating the image surface during zooming.

[0037] The second intermediate group GM2 moves along the optical axis during focusing from an object at infinity to a close object, and corrects deviations in the image position when the object distance changes.

[0038] The trailing group GR, which is made up of one or more lens groups, is responsible for image plane compensation as well as for correcting the lateral chromatic aberration that becomes significant at the telephoto end. By using glass material with positive anomalous dispersion for the concave lenses in the trailing group GR and glass material with negative anomalous dispersion for the convex lenses, the effect of correcting the g-line in the over direction is generated, making it possible to correct the lateral chromatic aberration at the telephoto end. In addition, in the trailing group GR, on-axis marginal rays pass through at a lower ray height than off-axis chief rays, so the correction effect of lateral chromatic aberration becomes greater at higher image heights while minimizing the deterioration of on-axis chromatic aberration.

[0039] On the other hand, if the lateral chromatic aberration on the telephoto side is corrected by using a glass material with positive anomalous dispersion for the concave lenses and a glass material with negative anomalous dispersion for the convex lenses in the subsequent lens group GR, the g-line will be over-corrected on the wide-angle side, causing the lateral chromatic aberration to worsen. However, by offsetting the lateral chromatic aberration that worsens on the wide-angle side with the correction effect of the lateral chromatic aberration of the second lens group G2, which has a large correction effect in the under-correction of the g-line on the wide-angle side, it becomes possible to correct the lateral chromatic aberration well over the entire range from the wide-angle end to the telephoto end.

[0040] In the variable magnification imaging optical system of the present invention, it is desirable to satisfy the following conditional expression (1) in order to achieve both a reduction in the overall length of the optical system and high performance. (1) 0.2 <f1 / fT<1.0 f1: focal length of the first lens group G1 fT: focal length of the entire system at the infinity telephoto end

[0041] Conditional formula (1) that must be satisfied by the variable magnification imaging optical system of the present invention prescribes the ratio of the focal length of the entire system at the infinity telephoto end to the focal length of the first lens group G1, and indicates a desirable range for shortening the overall length of the optical system and reducing the weight of the lens barrel.

[0042] If the upper limit of conditional formula (1) is exceeded and the focal length of the first lens group G1 becomes long relative to the focal length of the entire system at the infinity telephoto end, the total optical length at the telephoto end will be too long, increasing the amount of movement of the first lens group G1 due to zooming, complicating the movement mechanism, and increasing the size of the lens barrel.

[0043] If the lower limit of conditional formula (1) is exceeded and the focal length of the first lens group G1 becomes shorter than the focal length of the entire system at the infinity telephoto end, the imaging magnification of the composite system from the second lens group G2 onwards at the telephoto end will be too high, making it difficult to correct various aberrations such as axial chromatic aberration at the telephoto end.

[0044] In addition, it is preferable to set the lower limit of condition (1) to 0.3 and the upper limit to 0.7, so that the above-mentioned effect can be ensured more reliably.

[0045] In the variable magnification imaging optical system of the present invention, it is desirable to satisfy the following conditional expression (2) in order to achieve both a reduction in the overall length of the optical system and high performance. (2) 0.10 <f2 / fT<1.40 f2: the focal length of the second lens group G2 fT: focal length of the entire system at the infinity telephoto end

[0046] Conditional formula (2) that must be satisfied by the variable magnification imaging optical system of the present invention prescribes the ratio of the focal length of the entire system at the infinity telephoto end to the focal length of the second lens group G2, and indicates a desirable range for shortening the overall length of the optical system and reducing the weight of the lens barrel.

[0047] If the upper limit of conditional formula (2) is exceeded and the focal length of the second lens group G2 becomes longer than the focal length of the entire system at the infinity telephoto end, the positive refractive power combined by the first lens group G1 and the second lens group G2 will become smaller, making it difficult to shorten the overall length of the optical system. Also, if the insufficient combined refractive power of the first lens group G1 and the second lens group G2 is compensated for by strengthening the power of the first lens group G1, it will become difficult to use low-refractive-index, low-dispersion glass such as fluorite for the convex lens in the first lens group G1, which plays an important role in correcting axial chromatic aberration, making it difficult to improve performance.

[0048] If the lower limit of conditional formula (2) is exceeded and the focal length of the second lens group G2 becomes small relative to the focal length of the entire system at the infinity to telephoto end, the power of the second lens group G2 will be strong, making it difficult to suppress astigmatism and achieve high performance, particularly at the wide-angle end where the off-axis chief ray passes through a high position.

[0049] Incidentally, with regard to conditional expression (2), it is preferable to set the lower limit at 0.20 and the upper limit at 1.10, so that the above-mentioned effect can be ensured more reliably.

[0050] In the variable magnification image-forming optical system of the present invention, it is desirable to satisfy the following conditional expression (3) in order to effectively correct axial chromatic aberration and lateral chromatic aberration over the entire zoom range. (3) 0.2 <g2AXhW / g2AXhT<1.5 g2AXhW: Height of the axial marginal ray at the front surface of the second lens group G2 at the infinity wide-angle end with the aperture fully open g2AXhT: Height of the axial marginal ray at the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open An axial marginal ray is defined as a ray that passes through the aperture at the maximum height from the optical axis among the rays contained in the axial light beam.

[0051] Conditional formula (3) that the variable magnification imaging optical system of the present invention must satisfy defines the ratio between the height of an axial marginal ray at the front surface of the second lens group G2 at the infinity wide-angle end with the aperture fully open, and the height of an axial marginal ray at the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open.

[0052] As mentioned above, in the second lens group G2, in order to correct the g-line toward the under side at the wide-angle side and suppress lateral chromatic aberration, it is desirable to use a glass material with positive anomalous dispersion for the concave lens. On the other hand, if a glass material with strong positive anomalous dispersion and large ΔPgF is used for the concave lens of the second lens group G2, the imaging position of the g-line and C-line in the axial light beam will move toward the image side, which will act in the direction of increasing the secondary spectrum and work against the correction of axial chromatic aberration. Furthermore, since axial chromatic aberration becomes more noticeable as the angle of view becomes narrower on the telephoto side, the deterioration of axial chromatic aberration must also be suppressed in order to achieve high image quality. Therefore, in order to prevent the deterioration of axial chromatic aberration while using a glass material with strong positive anomalous dispersion, which is advantageous for correcting lateral chromatic aberration on the wide-angle side, it is necessary to control the height of the axial marginal ray to be small relative to the effective diameter of the second lens group G2 (in the case of the second lens group G2, the effective diameter is determined by the height of the off-axial ray flux at the maximum angle of view at the wide-angle end), and control of the height of the axial marginal ray is particularly important on the telephoto side.

[0053] If the upper limit of conditional expression (3) is exceeded and the ratio between the height of the axial marginal ray at the front surface of the second lens group G2 at the infinity wide-angle end at full aperture and the height of the axial marginal ray at the front surface of the second lens group G2 at the infinity wide-angle end at full aperture becomes large, the height of the axial marginal ray at the front surface of the second lens group G2 at the infinity wide-angle end at full aperture becomes too large, making it difficult to correct axial chromatic aberration on the wide-angle side and making it necessary to strengthen the power of the first lens group G1 in order to lower the height of the axial marginal ray at the telephoto side, resulting in a deterioration of various aberrations and making it difficult to achieve high performance.

[0054] If the lower limit of conditional formula (3) is exceeded and the ratio between the height of the axial marginal ray at the first surface of second lens group G2 at the infinity wide-angle end with the aperture fully open and the height of the axial marginal ray at the first surface of second lens group G2 at the infinity telephoto end with the aperture fully open becomes small, the height of the axial marginal ray at the first surface of second lens group G2 at the infinity telephoto end with the aperture fully open becomes large, making it difficult to correct axial chromatic aberration and achieve high performance.

[0055] As for condition (3), it is preferable to set the lower limit to 0.3 and the upper limit to 1.3, so that the above-mentioned effect can be ensured more reliably.

[0056] Furthermore, in the variable magnification image forming optical system of the present invention, the second lens group G2, in which the change in ray height of the off-axial chief ray is large when zooming from the wide-angle end to the telephoto end, plays an important role in effectively correcting the lateral chromatic aberration that varies with zooming, and in order to achieve high performance in the optical system, it is desirable to satisfy the following conditional expressions (4) and (5). (4)-1.8<(g2OAhW / Wih)-(g2hrT / Tih)<-0.3 (5) 0.6<|g2OAhW / g2AXhT|<2.5 Wih: Image height of the off-axis chief ray at the maximum angle of view at the wide-angle end at infinity Tih: Image height of the off-axis chief ray at the maximum angle of view at the telephoto end at infinity g2OAhW: Height of the off-axis chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity wide-angle end g2OAhT: Height of the off-axis chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity telephoto end g2AXhT: Height of the axial marginal ray at the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open Note that the g2OAhW ray corresponds to Wih, and the g2OAhT ray corresponds to Tih. Since the second lens group G2 is located on the object side of the aperture stop S and the quadrant through which the light rays pass is reversed, g2OAhW and g2OAhT have opposite signs for Wih and Tih. Moreover, the axial marginal ray is defined as a ray that passes through the stop at the maximum height from the optical axis among the rays contained in the axial light beam.

[0057] Conditional formula (4) specifies a desirable range for the difference between the ratio of the height of the off-axial chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity wide-angle end to the image height of the off-axial chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity telephoto end to the image height of the off-axial chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity telephoto end. As this difference increases toward 0, it means that the change in the off-axial chief ray in the second lens group G2 when zooming from the infinity wide-angle end to the infinity telephoto end is small, and conversely, as it decreases in the direction away from 0, it means that the change in the off-axial chief ray in the second lens group G2 when zooming from the infinity wide-angle end to the infinity telephoto end is large.

[0058] If the upper limit of conditional expression (4) is exceeded and the difference between the ratio of the height of the off-axial chief ray at the maximum angle of view at the first surface of the second lens group G2 at the infinity wide-angle end to the image height formed by the off-axial chief ray at the maximum angle of view at the same wide-angle end, and the ratio of the height of the off-axial chief ray at the maximum angle of view at the first surface of the second lens group G2 at the infinity telephoto end to the image height formed by the off-axial chief ray at the maximum angle of view at the same telephoto end, approaches 0, the change in the off-axial chief ray at the second lens group G2 when zooming from the infinity wide-angle end to the infinity telephoto end will be small, reducing the effect of correcting lateral chromatic aberration, and the lateral chromatic aberration cannot be sufficiently corrected on either the wide-angle side or the telephoto side or both, which is not preferable.

[0059] If the lower limit of conditional formula (4) is exceeded and the difference between the ratio of the height of the off-axial chief ray at the maximum angle of view at the first surface of the second lens group G2 at the infinity wide-angle end to the image height formed by the off-axial chief ray at the maximum angle of view at the wide-angle end, and the ratio of the height of the off-axial chief ray at the maximum angle of view at the first surface of the second lens group G2 at the infinity telephoto end to the image height formed by the off-axial chief ray at the maximum angle of view at the telephoto end, decreases away from 0, then the change in the off-axial chief ray at the second lens group G2 when zooming from the infinity wide-angle end to the infinity telephoto end becomes too large, making it difficult to correct astigmatism and field curvature, which is not preferable.

[0060] As for condition (4), it is preferable to set the lower limit to -1.5 and the upper limit to -0.4, so that the above-mentioned effect can be ensured more reliably.

[0061] Conditional formula (5) specifies the absolute value of the ratio between the height of the off-axial chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity wide-angle end and the height of the on-axis marginal ray on the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open. The off-axial chief ray specified in conditional formula (5) means the off-axial chief ray at the maximum angle of view on the infinity wide-angle end specified in conditional formula (4).

[0062] When the upper limit of conditional formula (5) is exceeded and the absolute value of the ratio between the height of the off-axial chief ray at the maximum angle of view at the front surface of the second lens group G2 at the infinite wide-angle end and the height of the on-axis marginal ray at the front surface of the second lens group G2 at the infinite telephoto end at maximum aperture becomes large, it becomes necessary to strengthen the power of the first lens group G1 in order to lower the height of the on-axis marginal ray on the telephoto side, which causes various aberrations to worsen and makes it difficult to achieve high performance.

[0063] If the lower limit of conditional formula (5) is exceeded and the absolute value of the ratio between the height of the off-axial chief ray at the maximum angle of view at the front surface of the second lens group G2 at the infinity wide-angle end and the height of the on-axis marginal ray at the front surface of the second lens group G2 at the infinity telephoto end at the maximum aperture decreases, the height of the on-axis marginal ray does not decrease sufficiently on the telephoto side, and the on-axis chromatic aberration generated in the second lens group G2 increases, making it difficult to achieve high performance. Also, the absolute value of the height of the off-axial chief ray at the maximum angle of view at the infinity wide-angle end decreases (simply equivalent to the height of the off-axial chief ray from the optical axis decreasing without considering the concept of sign), making it difficult to correct chromatic aberration of magnification on the wide-angle side and making it difficult to achieve high performance.

[0064] As for condition (5), it is preferable to set the lower limit at 0.8 and the upper limit at 1.9, so that the above-mentioned effect can be ensured more reliably.

[0065] In addition, in the variable magnification image-forming optical system of the present invention, conditional expressions (6) to (9) specify the relationship between the second lens group G2 and the lens groups before and after it, which is necessary for the second lens group G2 to effectively correct the lateral chromatic aberration that varies when zooming from the wide-angle end to the telephoto end.

[0066] In the variable magnification image forming optical system of the present invention, it is desirable for the second lens group G2 to satisfy the following conditional expression (6) in order to effectively correct lateral chromatic aberration that varies with zooming from the wide-angle end to the telephoto end. (6) 0.005 <DG1G2W / DG1G2T<0.400 DG1G2W: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity wide-angle end DG1G2T: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity telephoto end

[0067] Conditional formula (6) specifies the ratio of the on-optical-axis spacing between the first lens group G1 and the second lens group G2 at the infinity wide-angle end and the infinity telephoto end. It is desirable for the second lens group G2 to have a correction effect for lateral chromatic aberration that corrects the g-line in the under-focus direction on the wide-angle side, and in order to enhance this effect, it is desirable for the off-axis chief ray to pass through a position where the height of the chief ray is higher on the wide-angle side, and on the telephoto side, as mentioned above, it is desirable for the on-axis marginal ray to pass through a position where the height of the chief ray is lower. Therefore, it is desirable for the spacing between the first lens group G1 and the second lens group G2 to be small at the wide-angle end and large at the telephoto end.

[0068] If the upper limit of conditional expression (6) is exceeded and the ratio of the on-axis distance between the first lens group G1 and the second lens group G2 at the infinity wide-angle end and the infinity telephoto end becomes large, the distance between the first lens group G1 and the second lens group G2 at the telephoto end becomes small, and the on-axis marginal ray height at the telephoto side does not decrease sufficiently, which leads to deterioration of on-axis chromatic aberration, which is undesirable. Also, if the distance between the first lens group G1 and the second lens group G2 at the wide-angle end becomes large, this acts in the direction of increasing the overall length of the product, which is also undesirable.

[0069] If the lower limit of conditional expression (6) is exceeded and the ratio of the on-optical-axis spacing between the first lens group G1 and the second lens group G2 at the infinity wide-angle end and the infinity telephoto end becomes small, the change in the off-axial chief ray in the second lens group G2 becomes too large when zooming from the infinity wide-angle end to the infinity telephoto end, making it difficult to correct astigmatism and field curvature, which is not preferable.

[0070] Regarding condition (6), it is preferable to set the lower limit to 0.009 and the upper limit to 0.200, so that the above-mentioned effect can be ensured more reliably.

[0071] In the variable magnification image forming optical system of the present invention, it is desirable for the second lens group G2 to satisfy the following conditional expression (7) in order to effectively correct lateral chromatic aberration that varies with zooming from the wide-angle end to the telephoto end. (7) 1.00 <DG2G3W / DG2G3T<80.00 DG2G3W: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end DG2G3T: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity telephoto end

[0072] Conditional formula (7) specifies the ratio of the on-optical-axis spacing between the second lens group G2 and the third lens group G3 at the infinity wide-angle end and the infinity telephoto end. It is desirable for the second lens group G2 to have a correction effect for lateral chromatic aberration that corrects the g-line in the under-focus direction on the wide-angle side, and in order to enhance this effect, it is desirable for the off-axis chief ray to pass through a position where the height of the chief ray is higher on the wide-angle side, and it is desirable for the on-axis marginal ray to pass through a position where the height of the chief ray is lower on the telephoto side, as described above. Therefore, it is desirable for the spacing between the second lens group G2 and the third lens group G3 to be large at the wide-angle end and small at the telephoto end.

[0073] If the upper limit of conditional expression (7) is exceeded and the ratio of the on-optical-axis spacing between the second lens group G2 and the third lens group G3 at the infinity wide-angle end and the infinity telephoto end becomes large, the change in the off-axial chief ray in the second lens group G2 becomes too large when zooming from the infinity wide-angle end to the infinity telephoto end, making it difficult to correct astigmatism and field curvature, which is undesirable.

[0074] If the lower limit of conditional expression (7) is exceeded and the ratio of the axial spacing between the second lens group G2 and the third lens group G3 at the infinity wide-angle end and the infinity telephoto end becomes small, the axial spacing between the second lens group G2 and the third lens group G3 at the wide-angle end becomes small, the off-axis chief ray cannot pass through a position with a sufficiently high height on the wide-angle side, and the effect of correcting the lateral chromatic aberration to correct the g-line in the under direction is reduced, which is undesirable. Also, if the axial spacing between the second lens group G2 and the third lens group G3 at the telephoto end becomes large, the height of the axial marginal ray passing through the second lens group G2 on the telephoto side does not decrease sufficiently, which is undesirable as it leads to deterioration of the axial chromatic aberration.

[0075] Incidentally, with regard to condition (7), it is preferable to set the lower limit to 1.10 and the upper limit to 40.00, so that the above-mentioned effect can be ensured more reliably.

[0076] In the variable magnification image forming optical system of the present invention, it is desirable for the second lens group G2 to satisfy the following conditional expression (8) in order to effectively correct lateral chromatic aberration that varies with zooming from the wide-angle end to the telephoto end. (8) 0.01 <DG1G2W / DG2G3W<2.00 DG1G2W: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity wide-angle end DG2G3W: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end

[0077] Conditional formula (8) specifies the ratio of the axial distance between the first lens group G1 and the second lens group G2 at the infinity wide-angle end to the axial distance between the second lens group G2 and the third lens group G3. It is desirable for the second lens group G2 to have a correction effect of lateral chromatic aberration that corrects the g-line in the under-focus direction at the wide-angle end, and in order to enhance this effect, it is desirable for the second lens group G2 to pass through a position where the height of the off-axis chief ray is higher at the wide-angle end, and it is desirable for the second lens group G2 to pass through a position where the height of the on-axis marginal ray is low at the telephoto end, as described above. Therefore, at the infinity wide-angle end, when the second lens group G2 is closer to the first lens group G1, the distance between the first lens group G1 is shortened, and the distance between the second lens group G2 and the third lens group G3 is widened, the height of the off-axis chief ray passing through the second lens group G2 is higher, and lateral chromatic aberration is effectively corrected.

[0078] If the upper limit of conditional expression (8) is exceeded and the ratio of the axial distance between the first lens group G1 and the second lens group G2 at the infinity wide-angle end to the axial distance between the second lens group G2 and the third lens group G3 becomes large, the second lens group G2 will be too close to the third lens group G3 at the infinity wide-angle end, and the off-axial chief ray passing through the second lens group G2 will pass through a low position, which will make it difficult to effectively correct lateral chromatic aberration, and this is not preferable.

[0079] If the lower limit of conditional formula (8) is exceeded and the ratio of the axial distance between the first lens group G1 and the second lens group G2 at the infinity wide-angle end to the axial distance between the second lens group G2 and the third lens group G3 becomes small, the second lens group G2 will be too close to the first lens group G1 at the infinity wide-angle end, and the off-axial chief ray passing through the second lens group G2 will pass through a high position, increasing the effective diameter of the second lens group G2 and the weight of the optical system, which is undesirable.

[0080] As for condition (8), it is preferable to set the lower limit to 0.02 and the upper limit to 1.50, so that the above-mentioned effect can be ensured more reliably.

[0081] In the variable magnification image forming optical system of the present invention, it is desirable for the second lens group G2 to satisfy the following conditional expression (9) in order to effectively correct lateral chromatic aberration that varies with zooming from the wide-angle end to the telephoto end. (9)2.0 <DG1G2T / DG2G3T<200.0 DG1G2T: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity telephoto end DG2G3T: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity telephoto end

[0082] Conditional formula (9) specifies the ratio of the axial distance between the first lens group G1 and the second lens group G2 at the infinity telephoto end to the axial distance between the second lens group G2 and the third lens group G3. It is desirable for the second lens group G2 to have an effect of correcting lateral chromatic aberration by correcting the g-line in the under-focus direction at the wide-angle end, and in order to enhance this effect, it is desirable for the off-axis chief ray to pass through a position where the height is higher at the wide-angle end, and it is desirable for the axial marginal ray to pass through a position where the height is lower at the telephoto end, as described above. Therefore, at the infinity telephoto end, if the second lens group G2 is closer to the third lens group G3, the distance between the first lens group G1 and the third lens group G3 is wider, and the distance between the second lens group G2 and the third lens group G3 is narrower, the axial marginal ray passes through a lower position, and it is possible to suppress the deterioration of the axial chromatic aberration.

[0083] If the upper limit value of conditional expression (9) is exceeded and the ratio of the axial distance between the first lens group G1 and the second lens group G2 at the infinity telephoto end to the axial distance between the second lens group G2 and the third lens group G3 becomes large, the axial distance between the first lens group G1 and the second lens group G2 at the infinity telephoto end becomes too large, which undesirably enlarges the optical system.

[0084] If the lower limit of conditional expression (9) is exceeded and the ratio of the axial distance between the first lens group G1 and the second lens group G2 at the infinity telephoto end to the axial distance between the second lens group G2 and the third lens group G3 becomes small, the axial distance between the second lens group G2 and the third lens group G3 at the infinity telephoto end does not become small, and the axial marginal rays will pass through a high point, which will undesirably worsen axial chromatic aberration.

[0085] Regarding condition (9), it is preferable to set the lower limit to 3.0 and the upper limit to 150.0, and more preferably to set the lower limit to 4.0 and the upper limit to 120.0, thereby making it possible to ensure the above-mentioned effect.

[0086] In the variable magnification image forming optical system of the present invention, the second lens group G2, in which the ray height of the off-axis chief ray changes greatly during zooming from the wide-angle end to the telephoto end, plays an important role in effectively correcting the lateral chromatic aberration that varies with zooming, and it is desirable for the second lens group G2 to include at least one concave lens. Note that the concave lens shown here may be either a single lens or a concave lens that is arranged as part of a cemented lens.

[0087] For the second lens group G2, it is important to use a glass material that has the effect of correcting the g-line in the under direction on the wide-angle side in order to effectively correct lateral chromatic aberration on the wide-angle side. For convex lenses, it is desirable to select a glass material with negative anomalous dispersion, and for concave lenses, a glass material with positive anomalous dispersion. Glass materials with negative anomalous dispersion include high-refractive index, low-dispersion glass materials such as TAFD30 from HOYA, and Kruz-flint glass materials such as E-ADF10. Glass materials with positive anomalous dispersion include low-refractive index, low-dispersion glass materials such as FCD1 from HOYA, high-refractive index, high-dispersion glass materials such as E-FDS1-W from HOYA, and high-dispersion glass materials such as J-SFH4 from Hikari Glass. Comparing the two, glass materials with positive anomalous dispersion have a greater number of glass types, greater freedom in glass material selection, and also have greater anomalous dispersion, so it is desirable to include at least one concave lens in second lens group G2, and it is desirable to use a glass material with large positive anomalous dispersion for that concave lens.

[0088] Furthermore, in the variable magnification image forming optical system of the present invention, the second lens group G2, in which the change in height of the off-axial chief ray is large when zooming from the wide-angle end to the telephoto end, plays an important role in effectively correcting the lateral chromatic aberration that varies with zooming, and for this purpose it is desirable for the second lens group G2 to include at least one concave lens that satisfies the following conditional expression (10): (10)ΔPgFLg2>0.0090 ΔPgFLg2: Anomalous dispersion of the concave lens having the largest anomalous dispersion among the concave lenses included in the second lens group G2

[0089] Condition (10) defines the desirable range of anomalous dispersion for one or more concave lenses included in the second lens group G2. Note that the concave lens referred to here may be either a single lens or a concave lens that is arranged as part of a cemented lens.

[0090] As mentioned above, when zooming from the wide-angle end to the telephoto end, the second lens group G2 moves toward the image side with respect to the image plane, and the off-axis chief ray that passes through the second lens group G2 passes through a higher position on the wide-angle side and a lower position on the telephoto side. In order to suppress lateral chromatic aberration across the entire zoom range and achieve high performance, the second lens group G2 needs to correct more toward the under side for the g-line on the wide-angle side. Therefore, a larger ΔPgF and stronger positive anomalous dispersion are advantageous for correcting the g-line.

[0091] If the anomalous dispersion becomes small beyond the lower limit of condition (10), the effect of under-correcting the g-line at the wide-angle side decreases, making it difficult to suppress lateral chromatic aberration and achieve high performance over the entire zoom range.

[0092] Incidentally, by setting the lower limit of condition (10) to preferably 0.0095, more preferably 0.0100, and even more preferably 0.0150, it becomes possible to ensure the above-mentioned effect.

[0093] In the variable magnification imaging optical system of the present invention, it is desirable to satisfy the following conditional expression (11) in order to achieve both a reduction in the overall length of the optical system and high performance. (11)1.0 <f1 / fW<5.0 f1: focal length of the first lens group G1 fW: focal length of the entire system at the wide-angle end at infinity

[0094] Conditional expression (11) prescribes the ratio of the focal length of the entire system at the infinity wide-angle end to the focal length of the first lens group G1, and indicates a desirable range for achieving both a reduction in the overall length of the optical system and high performance.

[0095] If the upper limit of condition (11) is exceeded and the focal length of the first lens group G1 becomes large relative to the focal length of the entire system at the infinity wide-angle end, the refractive power of the first lens group G1 becomes insufficient, making it difficult to shorten the overall length of the optical system, which is not preferable.

[0096] If the lower limit of condition (11) is exceeded and the focal length of the first lens group G1 becomes small relative to the focal length of the entire system at the infinity wide-angle end, the refractive power of the first lens group G1 will be too strong, making it difficult to correct various aberrations such as spherical aberration and astigmatism, and therefore difficult to achieve high performance, which is not preferable.

[0097] As for condition (11), it is preferable to set the lower limit to 1.3 and the upper limit to 4.0, so that the above-mentioned effect can be ensured more reliably.

[0098] In the variable magnification image-forming optical system of the present invention, it is desirable to satisfy the following condition (12) in order to achieve both a reduction in the overall length of the optical system and high performance. (12)0.5 <f2 / fW<8.5 f2: the focal length of the second lens group G2 fW: focal length of the entire system at the wide-angle end at infinity

[0099] Conditional expression (12) prescribes the ratio of the focal length of the entire system at the infinity wide-angle end to the focal length of the second lens group G2, and indicates a desirable range for achieving both a reduction in the overall length of the optical system and high performance.

[0100] If the upper limit of conditional expression (12) is exceeded and the focal length of the second lens group G1 becomes large relative to the focal length of the entire system at the infinity wide-angle end, the refractive power of the second lens group G2 will be insufficient, making it difficult to shorten the overall length of the optical system. At the same time, it will be necessary to compensate for the insufficient refractive power by strengthening the refractive power of the first lens group G1, which will increase the aberration generated in the first lens group G1 and make it difficult to improve performance, which is undesirable.

[0101] If the lower limit of condition (12) is exceeded and the focal length of the second lens group G2 becomes small relative to the focal length of the entire system at the infinity wide-angle end, the refractive power of the second lens group G2 will become too strong, causing large coma and astigmatism to occur in the second lens group, making it difficult to improve performance, which is not preferable.

[0102] As for condition (12), it is preferable to set the lower limit to 0.7 and the upper limit to 7.5, so that the above-mentioned effect can be ensured more reliably.

[0103] In the variable magnification image-forming optical system of the present invention, it is desirable to satisfy the following condition (13) in order to realize effective correction of lateral chromatic aberration over the entire zoom range. (13)1.2 <DG2Sw / DG2St<5.0 DG2Sw: the distance from the apex of the object side of the lens closest to the object in the second lens group G2 at the wide-angle end to the aperture DG2St: the distance from the apex of the object side of the lens closest to the object in the second lens group G2 at the telephoto end to the aperture

[0104] Conditional formula (13) that the variable magnification imaging optical system of the present invention should satisfy defines a desirable range for the ratio of the distance from the apex of the object side of the lens closest to the object in the second lens group G2 to the aperture stop S at the wide-angle end and the telephoto end. As described above, when the second lens group G2 of the variable magnification imaging optical system of the present invention is changed from the wide-angle end to the telephoto end, the second lens group G2 moves toward the image side and the distance between the second lens group G2 and the third lens group G3 decreases, thereby shortening the distance between the second lens group G2 and the aperture stop S included in the first intermediate group GM1. It is desirable that the effect of the correction of lateral chromatic aberration of the second lens group G2 is large on the wide-angle side and small on the telephoto side, so that the second lens group G2 moves closer to the aperture stop S on the telephoto side and the height of the off-axis chief ray passing through the second lens group G2 decreases.

[0105] When the lower limit of conditional expression (13) is exceeded and the ratio between the distance from the apex of the object-side surface of the lens in the second lens group G2 closest to the object to the diaphragm at the wide-angle end and the telephoto end becomes small, the amount of change in the distance between the second lens group G2 and the aperture diaphragm S caused by magnification change becomes small, and the change in the off-axis chief ray passing through the second lens group G2 caused by magnification change becomes small, which reduces the change in the correction effect of the lateral chromatic aberration and makes it difficult to effectively correct the lateral chromatic aberration over the entire zoom range, which is not preferable.

[0106] If the upper limit of conditional expression (13) is exceeded and the ratio between the distance from the apex of the object-side surface of the lens closest to the object in the second lens group G2 to the diaphragm at the wide-angle end and the telephoto end becomes large, the amount of change in the distance between the second lens group G2 and the aperture diaphragm S due to magnification becomes large, and the off-axial light beam at the wide-angle end needs to pass through a higher point, which undesirably leads to an increase in the outer diameter of the second lens group G2.

[0107] Incidentally, by setting the lower limit of condition (13) to 1.4 and the upper limit to 3.5, it is possible to ensure the above-mentioned effect.

[0108] In the variable magnification image-forming optical system of the present invention, the second intermediate group GM2 is the group that moves the greatest amount of movement from infinity at the telephoto end to the close range end among the groups that move in the optical axis direction during focusing from an object at infinity to an object at a close range, and it is desirable for the second intermediate group GM2 to satisfy the following conditional expression (14): (14) 0.05<|fGM2 / fT|<0.40 fGM2: focal length of the second intermediate group GM2 fT: focal length of the entire system at the infinity telephoto end

[0109] Condition (14) prescribes the absolute value of the ratio between the focal length of the second intermediate group GM2 and the focal length of the entire system at the infinity to telephoto limit.

[0110] The second intermediate group GM2 is the group that moves the largest amount of movement from infinity at the telephoto end to the closest end among the groups that move in the optical axis direction during focusing from an object at infinity to an object at a close distance, and is the group that plays a major role in the effect of image plane correction that corrects the shift in the image point that occurs when the object distance changes. Increasing the power of the second intermediate group GM2 makes it possible to shorten the amount of movement during focusing, but this is not preferable as it results in a large deterioration in performance during focusing. Satisfying conditional expression (14) makes it possible to achieve both an increase in focusing speed and suppression of deterioration in performance during focusing.

[0111] If the lower limit of conditional formula (14) is exceeded and the ratio of the focal length of the second intermediate group GM2 to the focal length of the entire system at the infinity to telephoto end becomes small, the power of the second intermediate group GM2 will be insufficient, the moving distance of the second intermediate group GM2 from infinity to the close range side will be long, and this will result in a decrease in focusing speed, which is not desirable.

[0112] If the upper limit of condition (14) is exceeded and the ratio of the focal length of the second intermediate group GM2 to the focal length of the entire system at the infinity telephoto end becomes large, the power of the second intermediate group GM2 will become too strong, causing large fluctuations in performance due to the deterioration of various aberrations during focusing, which is undesirable.

[0113] Incidentally, with regard to condition (14), it is preferable to set the lower limit to 0.07 and the upper limit to 0.30, so that the above-mentioned effect can be more reliably achieved.

[0114] Furthermore, in the variable magnification image-forming optical system of the present invention, it is desirable that the lens group closest to the image side among the lens groups constituting the subsequent group GR includes at least one concave lens satisfying the following conditional expression (15): Note that the concave lens shown here may be either a single lens or a concave lens arranged as part of a cemented lens. (15) ΔPgFnLr>0.009 ΔPgFnLr: Anomalous dispersion of the concave lens in the rear group GR

[0115] Conditional formula (15) specifies the anomalous dispersion of a concave lens, of which at least one is preferably included in the lens group closest to the image among the lens groups constituting the subsequent group GR of the variable magnification imaging optical system of the present invention. In the variable magnification imaging optical system of the present invention, short wavelength light, particularly light rays on the wavelength side shorter than the g-line, is undercorrected on the telephoto side, resulting in a decrease in imaging magnification and leaving lateral chromatic aberration in the under direction. To effectively correct this, it is desirable to use a glass material with a large ΔPgF and strong positive anomalous dispersion for the concave lenses in the group behind the aperture stop S.

[0116] If the lower limit of condition (15) is exceeded and the anomalous dispersion of the concave lens element constituting the subsequent group GR becomes small, the effect of over-correcting the g-line at peripheral image heights on the telephoto side becomes small, making it difficult to correct lateral chromatic aberration throughout the entire zoom range.

[0117] With regard to the lower limit of condition (15), it is preferable to set the lower limit at 0.010, more preferably at 0.011, and even more preferably at 0.013, in order to ensure the above-mentioned effect.

[0118] Furthermore, in the variable magnification image-forming optical system of the present invention, it is desirable that the lens group closest to the image side among the lens groups constituting the subsequent group GR includes at least one concave lens satisfying the following conditional expression (16): Note that the concave lens shown here may be either a single lens or a concave lens arranged as part of a cemented lens. (16) 0.80<νdLr×ΔPgFLr νdLr: Abbe number of the concave lens in the rear lens group GR ΔPgFLr: Anomalous dispersion of the concave lens in the rear group GR

[0119] Conditional formula (16) specifies the relationship between the Abbe number and anomalous dispersion of a concave lens, of which at least one is preferably included in the lens group closest to the image side among the lens groups constituting the rear group GR of the variable magnification imaging optical system of the present invention. In the variable magnification imaging optical system of the present invention, the correction of short wavelengths, particularly light rays shorter than the g-line, is insufficient on the telephoto side, resulting in a decrease in imaging magnification and leaving lateral chromatic aberration in the under direction. To effectively correct this, it is desirable to use a glass material with a large ΔPgF and large positive anomalous dispersion for the concave lens in the group behind the aperture stop S. In addition, glass materials that satisfy conditional formula (16) generally have a relatively low refractive index of about 1.7 or less, and not only have anomalous dispersion that is desirable for correcting lateral chromatic aberration, but also are advantageous for correcting Petzval sum because of their low refractive index.

[0120] If the lower limit of condition (16) is exceeded and the anomalous dispersion of the concave lens element constituting the subsequent group GR becomes small, the effect of over-correcting the g-line at peripheral image heights on the telephoto side becomes small, making it difficult to correct lateral chromatic aberration throughout the entire zoom range.

[0121] As for the lower limit of condition (16), it is preferable to set the lower limit at 0.85, which makes it possible to ensure the above-mentioned effect.

[0122] Furthermore, in the variable magnification image-forming optical system of the present invention, it is desirable that the lens group closest to the image side among the lens groups constituting the subsequent group GR includes at least one convex lens satisfying the following conditional expression (17): The convex lens shown here may be either a single lens or a convex lens arranged as part of a cemented lens. (17)ΔPgFpLr<-0.0010 ΔPgFpLr: Anomalous dispersion of the convex lens in the rear group GR

[0123] Conditional formula (17) specifies the anomalous dispersion of at least one convex lens included in the lens group closest to the image among the lens groups constituting the subsequent group GR in the variable magnification image-forming optical system of the present invention, and in the variable magnification image-forming optical system of the present invention, the imaging magnification of light rays with short wavelengths, particularly light rays from the g-line to the short wavelength side, decreases on the telephoto side, and lateral chromatic aberration in the under direction remains. To effectively correct this, it is desirable to use a glass material with small ΔPgF and strong negative anomalous dispersion for the convex lenses in the group behind the aperture stop S.

[0124] If the upper limit of condition (17) is exceeded and the anomalous dispersion of the two convex lenses furthest from the image side among the succeeding group becomes large, the effect of over-correcting the g-line on the telephoto side decreases, making it difficult to suppress lateral chromatic aberration throughout the entire zoom range.

[0125] Incidentally, with regard to condition (17), by setting the upper limit to preferably −0.0020, more preferably −0.0030, and even more preferably −0.0040, it becomes possible to ensure the above-mentioned effect.

[0126] In the variable magnification image-forming optical system of the present invention, it is desirable that the average value of the anomalous dispersion of the two convex lenses counted closest to the image side satisfy the range of conditional expression (18). Note that the convex lens shown here may be either a single lens or a convex lens arranged as part of a cemented lens. (18)ΔPgFprAVE<-0.0010 ΔPgFprAVE: Average value of anomalous dispersion of the two convex lenses closest to the image side

[0127] Conditional formula (18) specifies the average value of the anomalous dispersion of the two convex lenses counted from the image side in the variable magnification imaging optical system of the present invention, and in the variable magnification imaging optical system of the present invention, the imaging magnification of light rays with short wavelengths, particularly light rays from the g-line to the short wavelength side, decreases on the telephoto side, and lateral chromatic aberration in the under direction remains. To effectively correct this, it is desirable to use a glass material with small ΔPgF and strong negative anomalous dispersion for the convex lenses in the group behind the aperture stop S.

[0128] If the upper limit of condition (18) is exceeded and the anomalous dispersion of the two convex lenses furthest from the image side that make up the subsequent group GR becomes large, the effect of over-correcting the g-line on the telephoto side decreases, making it difficult to suppress lateral chromatic aberration throughout the entire zoom range.

[0129] Incidentally, with regard to condition (18), by setting the upper limit to preferably −0.0020, more preferably −0.0030, and even more preferably −0.0040, it becomes possible to ensure the above-mentioned effect.

[0130] In the variable magnification image-forming optical system of the present invention, in order to prevent the mechanical structure from becoming complicated, it is desirable that the lens unit closest to the image side among the rear lens unit GR be fixed with respect to the image plane during zooming.

[0131] Next, a lens configuration of an embodiment of the imaging optical system of the present invention will be described. In the following description, the lens configuration will be described in order from the object side to the image side.

[0132] In [Surface Data], the surface number is the lens surface or aperture stop S number counted from the object side, r is the radius of curvature of each lens surface, d is the distance between each lens surface, nd is the refractive index for the d-line (wavelength 587.56 nm), vd is the Abbe number for the d-line, and ΔPgF is a value calculated using the formula PgF-0.64833+0.00180×vd. In addition, the names of glass materials from HOYA, OHARA, Hikari Glass, and Schott are listed as examples of glass that meet the refractive index, Abbe number, and ΔPgF listed in [Surface Data].

[0133] The asterisk (*) next to the surface number indicates that the lens surface is aspheric due to its shape. Also, BF is the back focus, and the object distance is the distance from the subject to the first lens surface.

[0134] The (stop) next to a surface number indicates that the aperture stop S is located at that position. The radius of curvature for the plane or aperture stop S is marked as ∞ (infinity).

[0135] [Aspheric Data] shows the values ​​of each coefficient that gives the aspheric shape of lens surfaces marked with an * in [Surface Data]. The shape of an aspheric surface is expressed by the following formula. In the formula below, the displacement from the optical axis in a direction perpendicular to the optical axis is represented by y, the displacement (amount of deviation) from the intersection of the optical axis with the aspheric surface in the direction of the optical axis is represented by z, the radius of curvature of the reference sphere is represented by r, and the Conic coefficient is represented by K. Additionally, the aspheric coefficients of 4th, 6th, 8th, 10th, and 12th orders are represented by A4, A6, A8, A10, and A12, respectively. TIFF2024000053000002.tif26123

[0136] [Various Data] shows values ​​such as focal length at each shooting distance and focus state.

[0137] [Variable Distance Data] shows the variable distance and BF values ​​at various shooting distances and focusing states.

[0138] [Lens group data] shows the surface number of each lens group closest to the object and the composite focal length of the entire group.

[0139] In addition, in the aberration diagrams corresponding to the respective embodiments, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image surface and the meridional image surface, respectively.

[0140] In addition, for all of the values ​​of the following specifications, the focal length f, radius of curvature r, lens surface spacing d, and other length units are given in millimeters (mm) unless otherwise specified; however, since the same optical performance can be obtained with proportional enlargement and proportional reduction in an optical system, this is not limited to this.

[0141] In the lens configuration diagrams of the respective embodiments, the arrow indicates the path of the lens group when changing magnification from the wide-angle end to the telephoto end, I indicates the image plane, F indicates a filter, and the dashed line passing through the center indicates the optical axis.

[0142] Next, a lens configuration of an embodiment of the imaging optical system of the present invention will be described. In the following description, the lens configuration will be described in order from the object side to the image side. EXAMPLES

[0143] FIG. 1 is a lens configuration diagram of a variable magnification image forming optical system according to the first embodiment when focused on infinity at the wide-angle end.

[0144] The variable magnification imaging optical system in Figure 1 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0145] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a cemented lens of a biconvex lens and a biconcave lens, a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the third to fifth lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side, and a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The sixth lens group G6 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a biconcave lens, and a cemented lens of a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and a biconcave lens.

[0146] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the eighth lens group G8 are fixed with respect to the image plane, the first lens group G1 moves toward the object side, the third lens group G3 to the seventh lens group each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0147] The values ​​of the specifications of the variable magnification imaging optical system according to the first embodiment are shown below. Numerical Example 1 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 219.7422 3.0000 1.55298 55.07 -0.0046 J-KZFH4 2 106.9237 0.1000 3 105.2496 12.8568 1.43875 94.66 0.0560 S-FPL55 4 -887.7919 0.3000 5 151.7135 7.3175 1.43875 94.66 0.0560 S-FPL55 6 689.3469 (d6) 7 87.1525 7.0725 1.77047 29.74 0.0002 NBFD29 8 -186.0599 1.7999 1.92286 20.88 0.0281 E-FDS1-W 9 1547.9303 (d9) 10 174.7842 4.0192 1.67270 32.17 0.0058 E-FD5 11 -98.3967 1.0000 1.91082 35.25 -0.0028 TAFD35 12 60.6855 5.8318 13 693.6052 1.0000 1.90525 35.04 -0.0005 S-LAH93 14 78.2972 3.6005 15 -52.4329 1.0000 1.80420 46.50 -0.0075 TAF3D 16 76.3499 3.8350 1.85451 25.15 0.0071 NBFD25 17 -241.0723 4.0000 18 -253.0121 1.0000 1.73037 32.23 -0.0005 NBFD32 19 46.8796 4.4089 1.85451 25.15 0.0071 NBFD25 20 334.9554 (d20) 21 177.7534 5.0873 1.59410 60.47 0.0156 FCD600 22 -62.7130 0.3000 23 73.0028 6.4463 1.43700 95.10 0.0564 FCD100 24 -56.9799 1.0000 1.91082 35.25 -0.0028 TAFD35 25 -296.3370 3.0000 26(Aperture) ∞ (d26) 27 44.0513 4.4496 1.49700 81.61 0.0373 FCD1 28 225.0247 0.9002 1.91082 35.25 -0.0028 TAFD35 29 51.1236 4.1248 30 291.1313 5.4778 1.51742 52.15 0.0044 E-CF6 31 -45.1872 0.9500 1.90043 37.37 -0.0045 TAFD37A 32 -61.1543 (d32) 33 62.9961 6.4690 1.59551 39.24 0.0026 S-TIM8 34 -78.7521 0.9000 1.90525 35.04 -0.0005 S-LAH93 35 -267.8528 (d35) 36 -170.7690 6.7388 1.82166 24.04 0.0186 MC-FDS910-50 37 -67.8981 1.0000 1.76385 48.49 -0.0022 S-LAH96 38 50.4060 2.3336 39 62.6479 6.5417 1.61340 44.27 -0.0054 S-NBM51 40 -45.1541 1.0000 1.43700 95.10 0.0564 FCD100 41 75.6923 (d41) 42 105.0556 6.8481 1.61340 44.27 -0.0054 S-NBM51 43 -40.3980 1.0000 1.59282 68.62 0.0192 FCD515 44 -69.8535 8.1268 45 -58.2019 1.0001 1.95375 32.32 -0.0002 TAFD45 46 196.8911 37.9233 47 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 48∞(BF) [Various data] Zoom ratio 3.74 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 154.50 300.00 577.80 F-number 4.70 5.21 6.46 Full angle of view 2ω 15.56 8.04 4.18 Image height Y 21.63 21.63 21.63 Lens total length 300.00 350.00 420.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.8704∞ (d6) 14.5648 14.5648 64.5649 (d9) 19.2200 19.2200 16.2362 (d20) 21.9127 21.9127 2.0000 (d26) 42.2772 42.2772 35.4570 (d32) 5.2027 2.0000 24.6206 (d35) 17.1492 20.3519 27.4616 (d41) 2.4139 2.4139 2.4002 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2456.2252∞2420.8805 (d6) 64.5649 134.5649 134.5649 (d9) 16.2362 2.0814 2.0814 (d20) 2.0000 2.0000 2.0000 (d26) 35.4570 20.8842 20.8842 (d32) 14.0812 22.8519 2.0000 (d35) 38.0010 3.5000 24.3519 (d41) 2.4002 56.8581 56.8581 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 236.2152 G2 7 133.6947 G3 10 -24.2947 G4 21 72.1099 G5 27 254.9799 G6 33 112.2107 G7 36 -90.5197 G8 42 -283.6465 EXAMPLES

[0148] FIG. 11 is a lens configuration diagram of a variable magnification image forming optical system according to Example 2 when focused on an object at infinity at the wide-angle end.

[0149] The variable magnification imaging optical system in Figure 11 is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0150] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a cemented lens of a biconvex lens and a biconcave lens, a convex meniscus lens with a convex surface facing the object side, a biconcave lens, and a cemented lens of a biconcave lens and a biconvex lens. In addition, the fourth and subsequent lenses from the object side in the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an anti-vibration group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens of a biconvex lens and a biconcave lens, and a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The sixth lens group G6 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with its convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with its convex surface facing the image side and a biconcave lens, and a cemented lens of a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with its convex surface facing the image side, and a biconcave lens.

[0151] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the eighth lens group G8 are fixed with respect to the image plane, the first lens group G1 moves toward the object side, the third lens group G3 to the fifth lens group G5 each move toward the object side, the sixth lens group G6 moves toward the image side, the seventh lens group G7 moves toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases. , the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object along the optical axis.

[0152] The values ​​of the specifications of the variable magnification imaging optical system according to the second embodiment are shown below. Numerical Example 2 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 313.9338 3.0000 1.61310 44.36 -0.0081 E-ADF10 2 127.3297 0.1000 3 125.9137 11.6998 1.43875 94.66 0.0560 S-FPL55 4 -833.5680 0.3000 5 138.0867 9.0391 1.43875 94.66 0.0560 S-FPL55 6 1594.3893 (d6) 7 107.9327 7.0586 1.65100 56.24 -0.0051 S-LAL54Q 8 -231.9455 1.0000 9 -213.8532 1.8000 1.66382 27.35 0.0327 J-SFH4 10 1071.3941 (d10) 11 574.4265 4.4878 1.80518 25.46 0.0131 FD60-W 12 -52.6286 1.0000 1.90525 35.04 -0.0005 S-LAH93 13 37.9856 2.4328 14 44.7912 3.2062 1.76182 26.61 0.0117 FD140 15 87.7005 9.2366 16 -100.1820 0.9000 1.72000 50.23 -0.0059 S-LAL10 17 78.6274 3.7951 18 -42.8383 1.0000 1.77250 49.62 -0.0088 TAF1 19 163.9164 4.2467 1.85451 25.15 0.0071 NBFD25 20 -70.2739 (d20) 21 2035.1510 3.4815 1.59410 60.47 0.0156 FCD600 22 -92.8817 0.3000 23 58.8047 6.7735 1.49700 81.61 0.0373 FCD1 24 -58.6839 1.0000 1.65100 56.24 -0.0051 S-LAL54Q 25 -301.5263 3.0000 26(Aperture) ∞ (d26) 27 37.9545 6.6018 1.43700 95.10 0.0564 FCD100 28 -163.8613 0.8999 1.85883 30.00 0.0035 NBFD30 29 47.4767 3.7133 30 128.5643 9.6559 1.65412 39.68 -0.0033 S-NBH5 31 -23.2865 1.0000 1.63854 55.38 -0.0002 S-BSM18 32 -73.5050 (d32) 33 51.4169 5.6996 1.48749 70.44 0.0090 FC5 34 -65.9030 0.9000 1.91082 35.25 -0.0028 TAFD35 35 -191.4230 (d35) 36 -65.2151 6.3532 1.84666 23.78 0.0136 FDS90-SG 37 -24.7782 0.8999 1.90525 35.04 -0.0005 S-LAH93 38 43.6797 2.0172 39 50.8986 8.8198 1.58144 40.89 0.0019 E-FL5 40 -22.6122 1.0499 1.43700 95.10 0.0564 FCD100 41 288.4604 (d41) 42 69.8285 12.0000 1.61340 44.27 -0.0054 S-NBM51 43 -29.9473 1.0001 1.66382 27.35 0.0327 J-SFH4 44 -50.2469 7.6319 45 -46.6736 1.0003 2.00100 29.13 0.0035 TAFD55-W 46 1278.0408 38.0000 47 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 48∞(BF) [Various data] Zoom ratio 3.74 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 154.50 300.00 577.80 F-number 4.70 5.21 6.46 Full angle of view 2ω 15.58 8.02 4.18 Image height Y 21.63 21.63 21.63 Lens total length 291.24 350.00 416.24 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.0000∞ (d6) 5.3029 5.3029 64.0600 (d10) 29.4531 29.4531 26.5873 (d20) 18.2967 1 8.2967 7.6367 (d26) 18.9828 18.9828 13.1925 (d32) 4.6509 2.0000 27.7941 (d35) 22.9563 25.6072 19.1294 (d41) 2.0000 2.0000 2.0000 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2500.0000∞ 2500.0000 (d6) 64.0600 130.3029 130.3029 (d10) 26.5873 9.9805 9.9805 (d20) 7.6367 2.0000 2.0000 (d26) 13.1925 2.0000 2.0000 (d32) 18.5365 61.3459 35.2387 (d35) 28.3870 3.5000 29.6072 (d41) 2.0000 17.5135 17.5135 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 247.8803 G2 7 193.2477 G3 11 -24.5769 G4 21 68.1910 G5 27 160.1374 G6 33 127.0838 G7 36 -54.8179 G8 42 469.5596 EXAMPLES

[0153] FIG. 21 is a lens configuration diagram of a variable magnification image forming optical system according to Example 3 when focusing on an object at infinity at the wide-angle end.

[0154] The variable magnification imaging optical system in Figure 21 is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to a close object, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0155] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with a convex surface facing the image side. The third lens group G3 is composed of a convex meniscus lens with a convex surface facing the image side, a biconcave lens, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the second to fourth lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a biconvex lens and a cemented lens of a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with a convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a biconcave lens, a concave meniscus lens with a convex surface facing the object side, and a cemented lens of a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and a concave meniscus aspherical lens whose convex surface faces the image side and whose image side surface has a specified aspherical shape.

[0156] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the eighth lens group G8 are fixed with respect to the image plane, the first lens group G1 moves toward the object side, the third lens group G3 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 increases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0157] The values ​​of the specifications of the variable magnification imaging optical system according to the third embodiment are shown below. Numerical Example 3 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 460.1969 2.9999 1.61310 44.36 -0.0081 E-ADF10 2 144.3557 0.1001 3 146.1176 11.4069 1.49700 81.54 0.0358 S-FPL51 4 -383.1217 0.2999 5 129.8536 6.6197 1.43875 94.66 0.0560 S-FPL55 6 293.7912 (d6) 7 372.9594 6.6746 1.64769 33.84 0.0049 E-FD2 8 -108.0460 1.5999 2.00069 25.46 0.0110 TAFD40-W 9 -261.4735 (d9) 10 -166.7703 2.9439 1.84666 23.78 0.0136 FDS90-SG 11 -83.2672 3.0504 12 -12057.0943 1.0000 1.90366 31.31 0.0027 TAFD25 13 95.9526 3.5302 14 -65.3746 1.0000 1.76385 48.49 -0.0022 S-LAH96 15 74.5154 4.4834 1.85451 25.15 0.0071 NBFD25 16 -150.8650 4.4158 17 -42.6539 1.0000 1.76385 48.49 -0.0022 S-LAH96 18 132.3897 2.9598 1.78880 28.43 0.0036 S-NBH58 19 6684.9210 (d19) 20 183.5007 4.1010 1.76385 48.49 -0.0022 S-LAH96 21 -110.8685 0.3000 22 55.3723 7.1568 1.43700 95.10 0.0564 FCD100 23 -60.4223 1.0000 1.77250 49.62 -0.0088 TAF1 24 -2514.0968 9.1908 25(Aperture) ∞ (d25) 26 87.2101 5.0861 1.49700 81.61 0.0373 FCD1 27 -91.0250 0.3000 28 28.7399 5.8998 1.49700 81.61 0.0373 FCD1 29 277.0772 1.0000 1.90043 37.37 -0.0045 TAFD37A 30 27.8069 (d30) 31 46.1337 5.0740 1.66672 48.32 -0.0005 S-BAH11 32 -33.6662 0.8999 1.76385 48.49 -0.0022 S-LAH96 33 -230.9634 (d33) 34 -99.1145 3.2044 1.67270 32.17 0.0058 E-FD5 35 -38.2447 5.4822 1.90525 35.04 -0.0005 S-LAH93 36 60.8790 2.2476 37 84.7442 0.9000 1.92286 20.88 0.0281 E-FDS1-W 38 32.6857 8.7431 1.73037 32.23 -0.0005 NBFD32 39 -22.7609 0.9999 1.49700 81.61 0.0373 FCD1 40 210.7969 (d40) 41 420.1833 7.8310 1.61310 44.36 -0.0081 E-ADF10 42 -22.7815 1.0000 1.53775 74.70 0.0254 S-FPM3 43 -287.9967 11.3260 44 -28.0781 1.1999 1.88202 37.22 -0.0045 MC-TAFD307 *45 -44.9175 34.4699 46 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 47∞(BF) [Aspheric data] 45 sides K 0.00000 A4 -1.55718E-06 A6 -3.01153E-09 A8 2.01865E-11 A10 -9.56512E-14 A12 1.65968E-16 [Various data] Zoom ratio 4.05 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 142.50 285.00 577.80 F-number 4.70 5.21 6.46 Full angle of view 2ω 16.98 8.51 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 342.20 410.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.8704∞ (d6) 10.4783 10.4783 72.6827 (d9) 38.9360 38.9360 35.5312 (d19) 29.0250 29.0250 11.8823 (d25) 2.0000 2.0000 4.5485 (d30) 9.1174 7.4493 27.1241 (d33) 8.7738 10.4419 13.2388 (d40) 6.6722 6.6722 2.1995 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2456.2252∞2420.8805 (d6) 72.6827 140.4784 140.4784 (d9) 35.5312 13.8280 13.8280 (d19) 11.8823 2.0000 2.0000 (d25) 4.5485 2.4555 2.4555 (d30) 20.7123 40.2991 23.9079 (d33) 19.6507 2.3978 18.7889 (d40) 2.1995 33.5441 33.5441 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 271.1762 G2 7 435.3000 G3 10 -35.4692 G4 20 70.9917 G5 26 611.7602 G6 31 67.4052 G7 34 -75.3409 G8 41 -255.8215 EXAMPLES

[0158] FIG. 31 is a lens configuration diagram of a variable magnification image forming optical system according to Example 4 when focusing on an object at infinity at the wide-angle end.

[0159] The variable magnification imaging optical system in Figure 31 is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to a close object, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0160] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with a convex surface facing the image side. The third lens group G3 is composed of a convex meniscus lens with a convex surface facing the image side, a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the second to fourth lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and an aperture stop S. The fifth lens group G5 is composed of a biconvex lens, and a cemented lens of a biconvex lens and a biconcave lens. The sixth lens group G6 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with its convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with its convex surface facing the image side and a biconcave lens, a concave meniscus lens with its convex surface facing the object side, and a cemented lens of a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a biconcave lens, and a concave meniscus aspherical lens with its convex surface facing the image side and whose surface on the image side has a specified aspherical shape.

[0161] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the eighth lens group G8 are fixed with respect to the image plane, the first lens group G1 moves toward the object side, the third lens group G3 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0162] The values ​​of the specifications of the variable magnification imaging optical system according to the fourth embodiment are shown below. Numerical Example 4 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 564.7048 3.0000 1.61336 44.49 -0.0094 N-KZFS4HT 2 168.6119 0.1000 3 169.5152 9.5011 1.49700 81.54 0.0358 S-FPL51 4 -593.6297 0.3000 5 142.5243 7.7748 1.43875 94.66 0.0560 S-FPL55 6 540.7236 (d6) 7 179.5996 6.1309 1.67270 32.17 0.0058 E-FD5 8 -177.9787 1.6000 1.92286 20.88 0.0281 E-FDS1-W 9 -572.0899 (d9) 10 -394.5217 2.4345 1.84666 23.78 0.0136 FDS90-SG 11 -188.5246 4.2219 12 2857.7287 1.0307 1.90525 35.04 -0.0005 S-LAH93 13 86.5725 3.5770 14 -69.2223 1.0000 1.76385 48.49 -0.0022 S-LAH96 15 69.2201 4.3621 1.85451 25.15 0.0071 NBFD25 16 -268.9390 4.3334 17 -59.0003 2.8124 1.77250 49.62 -0.0088 TAF1 18 172.5992 3.5327 1.90525 35.04 -0.0005 S-LAH93 19 2929.2995 (d19) 20 148.5159 5.7273 1.59282 68.62 0.0192 FCD515 21 -70.1853 0.3000 22 47.6224 9.1480 1.43700 95.10 0.0564 FCD100 23 -42.4210 1.0000 1.85135 40.10 -0.0067 MC-TAFD305 24 463.8381 3.2424 25(Aperture) ∞ (d25) 26 416.8343 5.3513 1.64769 33.84 0.0049 E-FD2 27 -52.1138 0.3000 28 39.4632 8.7845 1.43700 95.10 0.0564 FCD100 29 -86.4104 1.2700 1.87071 40.73 -0.0069 TAFD32 30 39.4015 (d30) 31 51.4786 4.6293 1.65412 39.68 -0.0033 S-NBH5 32 -40.5971 0.8999 1.90525 35.04 -0.0005 S-LAH93 33 -110.4973 (d33) 34 -94.0501 2.4659 1.85451 25.15 0.0071 NBFD25 35 -58.8174 1.0000 1.90525 35.04 -0.0005 S-LAH93 36 54.9816 3.6316 37 67.8676 0.9000 1.92286 20.88 0.0281 E-FDS1-W 38 34.5405 7.9312 1.73037 32.23 -0.0005 NBFD32 39 -27.2772 0.9999 1.49700 81.61 0.0373 FCD1 40 132.5925 (d40) 41 210.0613 7.8013 1.55836 54.01 -0.0094 N-KZFS2 42 -23.0240 0.9999 1.49700 81.61 0.0373 FCD1 43 1285.7572 12.8578 44 -27.5271 1.1999 1.88202 37.22 -0.0045 MC-TAFD307 *45 -42.7168 30.5000 46 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 47∞(BF) [Aspheric data] 45 sides K 0.00000 A4 -1.58639E-06 A6 -3.76873E-09 A8 1.65667E-11 A10 -4.44955E-14 A12 4.39343E-17 [Various data] Zoom ratio 4.05 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 142.50 285.00 577.80 F-number 4.70 5.21 6.46 Full angle of view 2ω 16.96 8.50 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 341.50 410.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.8704∞ (d6) 13.8517 13.8517 75.3488 (d9) 30.3567 30.3567 30.2087 (d19) 34.1319 34.1319 15.5301 (d25) 10.5193 10.5193 7.5385 (d30) 4.8460 2.9468 24.8768 (d33) 13.9437 15.8429 15.1764 (d40) 2.1989 2.1989 2.6659 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2456.2252∞2420.8805 (d6) 75.3488 143.8517 143.8517 (d9) 30.2087 15.4140 15.4140 (d19) 15.5301 3.8418 3.8418 (d25) 7.5385 2.2029 2.2029 (d30) 17.9019 31.7645 14.4748 (d33) 22.1513 2.1872 19.4768 (d40) 2.6659 40.5862 40.5862 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 286.3959 G2 7 253.3497 G3 10 -35.1007 G4 20 86.7866 G5 26 406.4777 G6 31 68.4201 G7 34 -83.0562 G8 41 -190.4140 EXAMPLES

[0163] FIG. 41 is a lens configuration diagram of a variable magnification image forming optical system according to Example 5 when focusing on an object at infinity at the wide-angle end.

[0164] The variable magnification imaging optical system in Figure 41 is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4, a fifth lens group G5, and a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, a second intermediate group GM2 consisting of a seventh lens group G7 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, and a subsequent group GR consisting of an eighth lens group G8 and a ninth lens group G9.

[0165] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a convex meniscus lens with a convex surface facing the object side, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 is composed of a cemented lens of a biconvex lens and a biconcave lens, a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the third to fifth lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens made of a biconcave lens and a biconvex lens. The sixth lens group G6 is composed of a cemented lens made of a convex meniscus lens with its convex surface facing the image side and a concave meniscus lens with its convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens made of a biconvex lens and a concave meniscus lens with its convex surface facing the image side. The eighth lens group G8 is composed of a cemented lens made of a convex meniscus lens with its convex surface facing the image side and a biconcave lens, and a cemented lens made of a biconvex lens and a biconcave lens. The ninth lens group G9 is composed of a cemented lens made of a biconvex lens and a concave meniscus lens with its convex surface facing the image side, and a concave meniscus lens with its convex surface facing the image side.

[0166] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the ninth lens group G9 are fixed with respect to the image plane, the first lens group G1 moves toward the object side, the third lens group G3 to the eighth lens group G8 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, and the distance between the fourth lens group G4 and The distance of the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 decreases, the distance between the sixth lens group G6 and the seventh lens group G7 increases, the distance between the seventh lens group G7 and the eighth lens group G8 decreases, and the distance between the eighth lens group G8 and the ninth lens group G9 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the image side and the seventh lens group G7 moves toward the object side along the optical axis. Also, the amount of movement due to focusing from an object at infinity to the close end at the telephoto end is greater for the seventh lens group G7 than for the sixth lens group G6 (however, a comparison is made as a simple amount of movement without considering whether the movement is positive or negative depending on the direction of movement).

[0167] The values ​​of the specifications of the variable magnification imaging optical system according to the fifth embodiment are shown below. Numerical Example 5 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 269.9273 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 112.6692 0.0999 3 111.5395 10.8116 1.49700 81.54 0.0358 S-FPL51 4 4431.7465 0.3000 5 147.0967 8.6478 1.43875 94.66 0.0560 S-FPL55 6 1789.1499 (d6) 7 93.0903 8.9999 1.72047 34.71 -0.0025 S-NBH8 8 -192.1464 1.7999 1.92286 18.90 0.0351 S-NPH2 9 -2966.3666 (d9) 10 124.9236 5.9007 1.84666 23.78 0.0136 FDS90-SG 11 -63.2375 1.0000 1.90043 37.37 -0.0045 TAFD37A 12 80.8045 5.4503 13 1061.7755 1.0000 1.90525 35.04 -0.0005 S-LAH93 14 77.6033 3.5062 15 -88.9429 1.0000 1.83481 42.74 -0.0066 S-LAH55VS 16 35.8630 5.1380 1.85451 25.15 0.0071 NBFD25 17 1633.7080 4.4725 18 -220.9096 1.0000 1.76182 26.61 0.0117 FD140 19 27.8597 6.1137 1.80610 33.27 -0.0001 NBFD15-W 20 215.5665 (d20) 21 102.4311 5.2026 1.49700 81.54 0.0358 S-FPL51 22 -65.8729 0.3000 23 63.4528 6.1678 1.43875 94.66 0.0560 S-FPL55 24 -54.9579 1.0000 1.88300 40.80 -0.0094 TAFD30 25 -292.0657 3.0000 26(Aperture) ∞ (d26) 27 -78.3364 1.0000 1.91082 35.25 -0.0028 TAFD35 28 90.9975 4.7536 1.43875 94.66 0.0560 S-FPL55 29 -77.8299 (d29) 30 -124.4927 5.3385 1.67270 32.10 0.0082 S-TIM25 31 -31.4622 0.9499 1.76385 48.49 -0.0022 S-LAH96 32 -47.3462 (d32) 33 72.9305 5.7314 1.66672 48.32 -0.0005 S-BAH11 34 -64.2889 0.8999 1.95375 32.32 0.0003 S-LAH98 35 -184.7573 (d35) 36 -163.6179 3.8259 1.77047 29.74 0.0002 NBFD29 37 -43.4046 1.0000 1.74400 44.79 -0.0023 S-LAM2 38 46.5819 2.1548 39 52.6726 6.5589 1.61310 44.36 -0.0081 E-ADF10 40 -46.9173 1.0000 1.43875 94.66 0.0560 S-FPL55 41 80.5430 (d41) 42 2222.8876 5.6807 1.74951 35.33 -0.0030 S-NBH51 43 -39.1070 1.0000 1.66382 27.35 0.0327 J-SFH4 44 -62.6396 11.5075 45 -45.4337 1.0000 1.95375 32.32 0.0003 S-LAH98 46 -635.9184 36.3700 47 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 48 ∞ (BF) [Various data] Zoom ratio 3.74 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 154.50 300.00 577.80 F-number 4.70 5.21 6.46 Full angle of view 2ω 15.56 8.03 4.18 Image height Y 21.63 21.63 21.63 Lens total length 300.00 350.00 420.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.8704∞ (d6) 16.6869 16.6869 66.6870 (d9) 18.0478 18.0478 15.9695 (d20) 38.5525 38.5525 12.0672 (d26) 16.5842 16.5842 3.1178 (d29) 6.4338 7.3076 5.1656 (d32) 6.2156 2.0000 46.1654 (d35) 18.0591 21.4009 17.9697 (d41) 3.2384 3.2384 6.6762 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2456.2252∞2420.8805 (d6) 66.6870 136.6870 136.6870 (d9) 15.9695 2.0000 2.0000 (d20) 12.0672 2.0000 2.0000 (d26) 3.1178 3.1718 3.1718 (d29) 5.7549 2.0000 5.6112 (d32) 34.5901 29.8127 5.0168 (d35) 28.9557 2.0339 23.2186 (d41) 6.6762 66.1129 66.1129 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 257.3766 G2 7 142.3422 G3 10 -30.1478 G4 21 69.0603 G5 27 -92.0724 G6 30 122.9491 G7 33 101.9794 G8 36 -101.3136 G9 42 -293.7021 EXAMPLES

[0168] FIG. 51 is a lens configuration diagram of a variable magnification image forming optical system according to Example 6 when focusing on an object at infinity at the wide-angle end.

[0169] The variable magnification imaging optical system in Figure 51 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, and a subsequent group GR consisting of a seventh lens group G7, an eighth lens group G8, and a ninth lens group G9 that move along the optical axis when focusing from an object at infinity to an object at a close distance.

[0170] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a biconvex lens, a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a biconvex lens. In addition, the second to fourth lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a biconvex lens, and a cemented lens of a biconvex lens and a biconcave lens. The sixth lens group G6 consists of a biconvex lens and a cemented lens of a concave meniscus lens with its convex surface facing the image side. The seventh lens group G7 consists of a convex meniscus lens with its convex surface facing the image side and a cemented lens of a biconcave lens. The eighth lens group G8 consists of a concave meniscus lens with its convex surface facing the object side and a cemented lens of a biconvex lens and a biconcave lens. The ninth lens group G9 consists of a cemented lens of a biconvex lens and a biconcave lens, and a concave meniscus lens with its convex surface facing the image side.

[0171] When changing magnification from the wide-angle end to the telephoto end, the second lens group G2 and the ninth lens group G9 are fixed with respect to the image plane, the first lens group G1 moves toward the object side, the third lens group G3 to the eighth lens group G8 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, and the distance between the fourth lens group G4 and the fifth lens group G5 decreases. The distance between group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, the distance between the seventh lens group G7 and the eighth lens group G8 decreases, and the distance between the eighth lens group G8 and the ninth lens group G9 increases, and when focusing from an object at infinity to an object at a close distance, the sixth lens group G6 moves toward the object side, and the seventh lens group G7 moves toward the image side or the object side along the optical axis. Also, the amount of movement during focusing from an object at infinity to the close distance end at the telephoto end is greater for the sixth lens group G6 than for the seventh lens group G7 (however, a comparison is made as a simple amount of movement without considering whether the movement is positive or negative depending on the direction of movement).

[0172] The values ​​of the specifications of the variable magnification imaging optical system according to the sixth embodiment are shown below. Numerical Example 6 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 404.9734 2.9999 1.55298 55.07 -0.0046 J-KZFH4 2 142.7479 0.0999 3 142.5136 10.8134 1.43875 94.66 0.0560 S-FPL55 4 -516.9418 0.2999 5 132.6564 6.9127 1.49700 81.54 0.0358 S-FPL51 6 315.8743 (d6) 7 246.8499 4.9474 1.85451 25.15 0.0071 NBFD25 8 -376.9692 1.6000 1.92286 18.90 0.0351 S-NPH2 9 852.0964 (d9) 10 345.5389 3.4744 1.53172 48.84 0.0025 S-TIL6 11 -137.4509 3.0000 12 843.9684 1.0000 1.85150 40.78 -0.0055 S-LAH89 13 82.0234 3.1953 14 -75.3119 1.0000 1.85150 40.78 -0.0055 S-LAH89 15 75.4351 3.7872 1.85451 25.15 0.0071 NBFD25 16 -423.6389 4.3443 17 -48.6820 1.0000 1.80400 46.53 -0.0070 S-LAH65VS 18 45.0953 5.2627 1.69895 30.13 0.0087 S-TIM35 19 -318.2078 (d19) 20 143.5763 4.4534 1.76385 48.49 -0.0022 S-LAH96 21 -101.2631 0.3000 22 62.7078 7.2896 1.43875 94.66 0.0560 S-FPL55 23 -51.0199 1.0000 1.77250 49.62 -0.0088 TAF1 24 -2852.4854 3.0000 25(Aperture) ∞ (d25) 26 134.2412 5.4326 1.49700 81.54 0.0358 S-FPL51 27 -61.9367 0.3000 28 38.1336 6.0536 1.43875 94.66 0.0560 S-FPL55 29 -161.4272 1.0000 1.77047 29.74 0.0002 NBFD29 30 40.2204 (d30) 31 59.0241 4.8537 1.69895 30.13 0.0087 S-TIM35 32 -40.2887 0.8999 1.95375 32.32 0.0003 S-LAH98 33 -150.4817 (d33) 34 -90.2327 2.6811 1.76182 26.52 0.0129 S-TIH14 35 -48.4183 1.0000 1.90525 35.04 -0.0005 S-LAH93 36 60.1209 (d36) 37 50.7573 0.8999 1.92286 18.90 0.0351 S-NPH2 38 26.9728 10.9417 1.77047 29.74 0.0002 NBFD29 39 -31.0511 0.9997 1.59522 67.73 0.0177 S-FPM2 40 111.4545 (d40) 41 90.7062 7.2714 1.61310 44.36 -0.0081 E-ADF10 42 -32.1297 0.9999 1.43875 94.66 0.0560 S-FPL55 43 108.4675 7.8763 44 -31.5068 1.1999 1.95375 32.32 0.0003 S-LAH98 45 -58.7369 34.4229 46 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 47∞(BF) [Various data] Zoom ratio 4.05 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 142.50 285.00 577.80 F-number 4.71 5.22 6.48 Full angle of view 2ω 17.15 8.60 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 337.15 410.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.0000∞ (d6) 2.0000 2.0000 59.1503 (d9) 47.0124 47.0124 48.0601 (d19) 23.1953 23.1953 9.2986 (d25) 15.6239 15.6239 9.6661 (d30) 3.2907 2.6539 15.3007 (d33) 15.9987 17.8968 19.1161 (d36) 10.7665 9.5052 14.4459 (d40) 2.0000 2.0000 2.0000 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2500.0000∞ 2500.0000 (d6) 59.1503 132.0000 132.0000 (d9) 48.0601 25.9556 25.9556 (d19) 9.2986 2.0000 2.0000 (d25) 9.6661 2.0000 2.0000 (d30) 6.8584 40.6770 23.9746 (d33) 26.4337 2.2861 22.2353 (d36) 15.5707 9.6785 6.4317 (d40) 2.0000 35.2902 35.2902 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 276.9187 G2 7 452.1000 G3 10 -32.6424 G4 20 70.9354 G5 26 229.7636 G6 31 84.4731 G7 34 -37.3354 G8 37 77.4187 G9 41 -234.3111 EXAMPLES

[0173] FIG. 61 is a lens configuration diagram of a variable magnification image forming optical system according to Example 7 when focusing on an object at infinity at the wide-angle end.

[0174] The variable magnification imaging optical system in Figure 61 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at close range, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0175] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a convex meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the first to third lenses in the third lens group G3 from the object side can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens of a concave meniscus lens with a convex surface facing the object side and a convex meniscus lens with a convex surface facing the object side, a biconvex lens, and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a biconcave lens, a concave meniscus lens with a convex surface facing the object side, and a cemented lens of a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a biconcave lens, and a concave meniscus lens with a convex surface facing the image side.

[0176] When changing magnification from the wide-angle end to the telephoto end, the eighth lens group G8 is fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0177] The values ​​of the specifications of the variable magnification imaging optical system according to the seventh embodiment are shown below. Numerical Example 7 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 468.9940 2.9999 1.61340 44.27 -0.0054 S-NBM51 2 191.8524 0.0999 3 189.2793 11.0838 1.49700 81.54 0.0358 S-FPL51 4 8539.7183 0.2999 5 353.4077 7.7739 1.43875 94.66 0.0560 S-FPL55 6 -3586.7354 0.3000 7 207.2513 7.7999 1.43875 94.66 0.0560 S-FPL55 8 605.3550 (d8) 9 181.5597 9.6314 1.73800 32.33 -0.0002 S-NBH53V 10 -357.1647 1.9999 1.92286 20.88 0.0281 E-FDS1-W 11 1586.4867 (d11) 12 3518.9083 1.0000 1.95375 32.32 -0.0002 TAFD45 13 86.4889 4.3539 14 -94.6327 1.0000 1.76385 48.49 -0.0022 S-LAH96 15 65.3209 4.6702 1.85451 25.15 0.0071 NBFD25 16 -1065.5782 3.7813 17 -149.7539 1.0000 1.77250 49.62 -0.0088 TAF1 18 197.5002 2.7855 1.85451 25.15 0.0071 NBFD25 19 2710.8726 (d19) 20 345.8921 3.4952 1.86966 20.02 0.0310 FDS20-W 21 -180.5725 0.3000 22 42.0493 3.5691 1.43700 95.10 0.0564 FCD100 23 61.3703 1.0000 1.85451 25.15 0.0071 NBFD25 24 32.4590 0.9627 25 32.6384 10.0457 1.43700 95.10 0.0564 FCD100 26 -60.6146 1.0000 1.88300 40.80 -0.0094 TAFD30 27 -447.2285 3.0000 28(Aperture) ∞ (d28) 29 122.4993 1.0000 1.77250 49.62 -0.0088 TAF1 30 47.5746 5.5177 1.43700 95.10 0.0564 FCD100 31 904.5708 0.3000 32 109.8835 5.2299 1.63980 34.47 0.0059 S-TIM27 33 -79.9106 0.3000 34 149.9195 0.8994 1.85451 25.15 0.0071 NBFD25 35 58.1935 (d35) 36 58.2883 5.5965 1.59551 39.24 0.0026 S-TIM8 37 -86.1386 0.8998 1.89190 37.13 -0.0035 S-LAH92 38 -376.8660 (d38) 39 -121.4442 5.7595 1.74077 27.76 0.0093 E-FD13 40 -26.9456 1.0000 1.76385 48.49 -0.0022 S-LAH96 41 45.4111 1.5000 42 37.6247 1.0000 1.86966 20.02 0.0310 FDS20-W 43 25.3857 11.3292 1.61340 44.27 -0.0054 S-NBM51 44 -29.8919 0.9997 1.43700 95.10 0.0564 FCD100 45 127.9456 (d45) 46 357.9797 6.8723 1.61340 44.27 -0.0054 S-NBM51 47 -25.5489 1.0000 1.55032 75.50 0.0274 FCD705 48 148.6520 15.3045 49 -31.3188 0.9001 1.92286 20.88 0.0281 E-FDS1-W 50 -48.5764 33.5405 51 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 52 ∞ (BF) [Various data] Zoom ratio 3.88 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 200.00 480.00 776.00 F-number 4.70 5.21 6.46 Full angle of view 2ω 12.05 5.04 3.12 Image height Y 21.63 21.63 21.63 Lens total length 360.00 410.00 470.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞3200.0000∞ (d8) 2.0000 2.0000 99.9221 (d11) 60.4022 60.4022 40.0782 (d19) 57.5857 57.5857 4.6230 (d28) 20.5394 20.5394 21.0540 (d35) 5.7002 2.6430 29.3075 (d38) 23.0217 26.0789 26.1449 (d45) 4.3492 4.3492 2.4686 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 3200.0000∞ 3200.0000 (d8) 99.9221 183.4961 183.4961 (d11) 40.0782 2.0595 2.0595 (d19) 4.6230 2.0000 2.0000 (d28) 21.0540 2.0000 2.0000 (d35) 13.2507 46.0015 18.7796 (d38) 42.2017 3.5000 30.7219 (d45) 2.4686 44.5413 44.5413 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 292.8770 G2 9 334.1784 G3 12 -43.9386 G4 20 135.4552 G5 29 262.0422 G6 36 109.0143 G7 39 -131.8489 G8 46 -104.9109 EXAMPLES

[0178] FIG. 71 is a lens configuration diagram of a variable magnification image forming optical system according to Example 8 when focusing on an object at infinity at the wide-angle end.

[0179] The variable magnification imaging optical system in Figure 71 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0180] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a concave meniscus lens with a convex surface facing the object side and a convex meniscus lens with a convex surface facing the object side, and a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the first to third lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and a cemented lens of a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a biconcave lens, and a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a biconcave lens, and a concave meniscus lens with a convex surface facing the image side.

[0181] When changing magnification from the wide-angle end to the telephoto end, the eighth lens group G8 is fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0182] The values ​​of the specifications of the variable magnification imaging optical system according to the eighth embodiment are shown below. Numerical Example 8 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 324.6183 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 140.5122 0.1000 3 137.9804 10.2814 1.49700 81.61 0.0373 FCD1 4 -674.2358 0.3000 5 158.0802 6.8363 1.43700 95.10 0.0564 FCD100 6 567.0974 (d6) 7 348.8723 1.0000 1.84666 23.78 0.0136 FDS90-SG 8 66.8665 8.7935 1.61340 44.27 -0.0054 S-NBM51 9 701.4091 0.3000 10 96.8924 8.2978 1.69895 30.05 0.0084 E-FD15L 11 -246.0741 1.6000 1.59282 68.62 0.0192 FCD515 12 1246.7646 (d12) 13 266.3161 1.0000 1.77250 49.62 -0.0088 TAF1 14 67.6365 4.1477 15 -75.3165 1.0000 1.76385 48.49 -0.0022 S-LAH96 16 74.9572 3.8645 1.85451 25.15 0.0071 NBFD25 17 -592.9077 3.6241 18 -122.0328 1.0000 1.88202 37.22 -0.0045 MC-TAFD307 19 81.2206 3.2727 1.86966 20.02 0.0310 FDS20-W 20 445.8328 (d20) 21 79.8940 3.9316 1.51633 64.14 0.0023 S-BSL7 22 -585.6576 0.3000 23 64.6446 5.3019 1.43700 95.10 0.0564 FCD100 24 -113.8727 1.0000 1.77250 49.62 -0.0088 TAF1 25 413.9537 3.2601 26(Aperture) ∞ (d26) 27 49.4701 1.0000 1.70300 52.38 -0.0035 S-LAL21 28 32.9142 6.7453 1.43700 95.10 0.0564 FCD100 29 -155.1860 0.3000 30 25.8177 3.3529 1.49700 81.61 0.0373 FCD1 31 38.6903 0.8999 1.91082 35.25 -0.0028 TAFD35 32 25.0006 (d32) 33 45.3948 4.5497 1.54072 47.20 0.0043 E-FEL2 34 -49.8166 0.9000 1.91082 35.25 -0.0028 TAFD35 35 -130.2481 (d35) 36 -76.5812 2.6342 1.60342 38.01 0.0028 E-F5 37 -43.1027 1.0000 1.80420 46.50 -0.0075 TAF3D 38 49.0719 2.8399 39 155.7562 0.9998 1.43700 95.10 0.0564 FCD100 40 50.0876 7.1251 1.61340 44.27 -0.0054 S-NBM51 41 -22.2197 0.9998 1.43700 95.10 0.0564 FCD100 42 117.9144 (d42) 43 76.9150 7.6093 1.61340 44.27 -0.0054 S-NBM51 44 -27.7159 0.9998 1.55032 75.50 0.0274 FCD705 45 271.0147 4.9215 46 -42.4664 0.9000 1.92286 20.88 0.0281 E-FDS1-W 47 -79.9616 36.2848 48 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 49∞(BF) [Various data] Zoom ratio 3.74 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 154.50 300.00 577.80 F-number 4.71 5.23 6.48 Full angle of view 2ω 15.63 8.04 4.18 Image height Y 21.63 21.63 21.63 Lens total length 275.00 334.54 380.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2450.0000∞ (d6) 2.2004 2.2004 80.8523 (d12) 31.9201 31.9201 21.3761 (d20) 43.2384 43.2384 20.7287 (d26) 14.8681 14.8681 15.2510 (d32) 6.1182 3.6782 17.8936 (d35) 14.8814 17.3214 11.4281 (d42) 2.0000 2.0000 7.2378 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2450.0000∞ 2450.0000 (d6) 80.8523 145.7629 145.7629 (d12) 21.3761 2.5402 2.5402 (d20) 20.7287 2.0000 2.0000 (d26) 15.2510 2.0000 2.0000 (d32) 10.0816 34.2305 14.7308 (d35) 19.2401 3.5000 22.9996 (d42) 7.2378 30.1932 30.1932 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 259.9946 G2 7 189.6140 G3 13 -37.1603 G4 21 105.2637 G5 27 204.3106 G6 33 87.1467 G7 36 -58.3507 G8 43 -961.1272 EXAMPLES

[0183] FIG. 81 is a lens arrangement diagram of a variable magnification image forming optical system according to Example 9 when focusing on an object at infinity at the wide-angle end.

[0184] The variable magnification imaging optical system of Figure 81 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0185] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a biconcave lens, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the first to third lenses in the third lens group G3 from the object side can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a biconvex lens, a cemented lens of a convex meniscus lens with a convex surface facing the object side, and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with its convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with its convex surface facing the image side and a biconcave lens, a concave meniscus lens with its convex surface facing the object side, and a cemented lens of a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a biconcave lens, and a concave meniscus aspherical lens with its convex surface facing the image side and whose surface on the image side has a specified aspherical shape.

[0186] When changing magnification from the wide-angle end to the telephoto end, the eighth lens group G8 is fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0187] The values ​​of the specifications of the variable magnification imaging optical system according to Example 9 are shown below. Numerical Example 9 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 390.4639 2.9999 1.61310 44.36 -0.0081 E-ADF10 2 141.0401 0.0999 3 139.6144 10.0607 1.49700 81.54 0.0358 S-FPL51 4 -877.3396 0.3000 5 153.3861 7.8915 1.43875 94.66 0.0560 S-FPL55 6 1156.8675 (d6) 7 170.2119 5.1347 1.75520 27.53 0.0102 E-FD4 8 -306.0893 1.6000 1.92286 20.88 0.0281 E-FDS1-W 9 434.5352 (d9) 10 -1117.3774 1.0000 1.91082 35.25 -0.0028 TAFD35 11 81.2891 3.4920 12 -72.5626 1.0000 1.80420 46.50 -0.0075 TAF3D 13 145.8122 4.0762 1.85451 25.15 0.0071 NBFD25 14 -93.1796 3.1130 15 -79.6029 1.0000 1.76385 48.49 -0.0022 S-LAH96 16 64.8769 3.6561 1.85451 25.15 0.0071 NBFD25 17 438.0363 (d17) 18 243.7252 3.8163 1.76385 48.49 -0.0022 S-LAH96 19 -106.1020 0.3000 20 74.1966 5.9555 1.43700 95.10 0.0564 FCD100 21 -62.5098 1.0000 1.77250 49.62 -0.0088 TAF1 22 -5727.8348 3.0000 23(Aperture) ∞ (d23) 24 75.4152 4.8007 1.43700 95.10 0.0564 FCD100 25 -116.7860 0.3000 26 30.4058 4.8626 1.49700 81.61 0.0373 FCD1 27 98.8187 1.0000 1.90525 35.04 -0.0005 S-LAH93 28 30.2436 (d28) 29 50.5125 5.7402 1.51742 52.15 0.0044 E-CF6 30 -45.4296 0.9001 1.85150 40.78 -0.0055 S-LAH89 31 -85.8852 (d31) 32 -387.8503 3.6425 1.85451 25.15 0.0071 NBFD25 33 -45.0783 1.0000 1.90525 35.04 -0.0005 S-LAH93 34 54.1152 3.1963 35 273.8144 1.0000 1.76385 48.49 -0.0022 S-LAH96 36 25.5281 10.4123 1.74330 49.22 -0.0104 NBF1 37 -23.3055 0.9999 1.59282 68.62 0.0192 FCD515 38 177.2352 (d38) 39 73.9776 7.9266 1.61310 44.36 -0.0081 E-ADF10 40 -26.3024 0.9999 1.59282 68.62 0.0192 FCD515 41 190.4267 6.3085 42 -29.3303 1.1997 1.85135 40.10 -0.0067 M-TAFD305 *43 -44.2911 35.1327 44 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 45∞(BF) [Aspheric data] 43 sides K 0.00000 A4 -1.48248E-06 A6 8.56692E-11 A8 -9.05631E-12 A10 1.52818E-14 A12 0.00000E+00 [Various data] Zoom ratio 7.01 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 82.40 285.00 577.80 F-number 4.71 5.22 6.47 Full angle of view 2ω 30.29 8.53 4.18 Image height Y 21.63 21.63 21.63 Lens total length 290.00 329.01 400.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.0000∞ (d6) 2.0000 2.0000 78.6839 (d9) 23.2786 23.2786 41.2241 (d17) 60.3272 60.3272 15.3287 (d23) 29.2904 29.2904 2.0000 (d28) 12.6251 11.8747 9.4363 (d31) 8.0609 8.8114 14.2761 (d38) 2.0000 2.0000 15.6417 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2500.0000∞ 2500.0000 (d6) 78.6839 162.0425 162.0425 (d9) 41.2241 2.3812 2.3812 (d17) 15.3287 2.0000 2.0000 (d23) 2.0000 2.0000 2.0000 (d28) 3.2835 48.4987 29.3127 (d31) 20.4289 3.5000 22.6860 (d38) 15.6417 27.1599 27.1599 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 261.9536 G2 7 553.4500 G3 10 -40.3177 G4 18 88.6205 G5 24 355.9694 G6 29 78.8055 G7 32 -69.5813 G8 39 -375.7864 EXAMPLES

[0188] FIG. 91 is a lens configuration diagram of a variable magnification image forming optical system according to Example 10 when focusing on an object at infinity at the wide-angle end.

[0189] The variable magnification imaging optical system of Figure 91 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at a close distance, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0190] Starting from the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a convex meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a biconvex lens, a biconcave lens, a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the second to fourth lenses from the object side of the third lens group G3 can be moved together in a direction perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens of a concave meniscus lens with a convex surface facing the object side and a convex meniscus lens with a convex surface facing the object side, a biconvex lens, and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a biconvex lens and a cemented lens of a biconcave lens. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a biconcave lens, a concave meniscus lens with a convex surface facing the object side, and a cemented lens of a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a concave meniscus lens with a convex surface facing the image side, and a concave meniscus aspherical lens whose convex surface faces the image side and whose image-side surface has a predetermined aspherical shape.

[0191] When changing magnification from the wide-angle end to the telephoto end, the eighth lens group G8 is fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0192] The values ​​of the specifications of the variable magnification imaging optical system according to the tenth embodiment are shown below. Numerical Example 10 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 425.1371 2.9999 1.61340 44.27 -0.0054 S-NBM51 2 182.7778 0.0998 3 180.8148 11.0084 1.49700 81.54 0.0358 S-FPL51 4 2162.6461 0.2999 5 363.5799 7.8479 1.43875 94.66 0.0560 S-FPL55 6 -2564.6623 0.3000 7 210.2580 7.8719 1.43875 94.66 0.0560 S-FPL55 8 644.7379 (d8) 9 169.2274 8.3708 1.85026 32.27 0.0026 S-LAH71 10 -833.5870 1.9987 1.92286 20.88 0.0281 E-FDS1-W 11 431.7262 (d11) 12 462.8454 3.5640 1.84666 23.78 0.0136 FDS90-SG 13 -204.0706 2.5657 14 -166.5873 1.0000 1.90525 35.04 -0.0005 S-LAH93 15 70.7633 4.1051 16 -228.4537 1.0000 1.60562 43.71 0.0023 S-BAM4 17 45.8915 5.8856 1.85451 25.15 0.0071 NBFD25 18 2110.6678 4.5031 19 -96.6205 1.0000 1.90525 35.04 -0.0005 S-LAH93 20 101.1779 3.4172 1.74950 35.28 0.0021 S-LAM7 21 702.4532 (d21) 22 126.3975 4.5312 1.85451 25.15 0.0071 NBFD25 23 -152.5754 2.5000 24 70.4290 5.1570 1.49700 81.61 0.0373 FCD1 25 -186.4304 1.0000 1.74951 35.33 -0.0030 S-NBH51 26 53.8046 3.5188 27 54.7492 7.4790 1.43700 95.10 0.0564 FCD100 28 -54.4798 1.0000 1.91082 35.25 -0.0028 TAFD35 29 -521.9889 3.0000 30 (Aperture) (d30) 31 56.2396 1.0000 1.90366 31.31 0.0027 TAFD25 32 38.5480 6.0947 1.43700 95.10 0.0564 FCD100 33 504.5929 10.0617 34 95.6338 4.8381 1.57135 52.95 0.0023 S-BAL3 35 -95.7409 0.5526 36 80.2094 0.8999 1.85150 40.78 -0.0055 S-LAH89 37 40.2550 (d37) 38 51.5327 5.1725 1.64769 33.84 0.0049 E-FD2 39 -104.5697 0.8998 1.90525 35.04 -0.0005 S-LAH93 40 1302.4788 (d40) 41 -145.0875 6.0005 1.73037 32.23 -0.0005 NBFD32 42 -24.4762 1.0000 1.76385 48.49 -0.0022 S-LAH96 43 35.3149 1.5000 44 30.8617 1.0000 1.92286 20.88 0.0281 E-FDS1-W 45 22.2062 11.9993 1.61340 44.27 -0.0054 S-NBM51 46 -26.8076 0.9997 1.43700 95.10 0.0564 FCD100 47 107.9779 (d47) 48 -362.7586 7.0547 1.61310 44.36 -0.0081 E-ADF10 49 -24.0120 0.9998 1.43700 95.10 0.0564 FCD100 50 -66.6605 4.1502 51 -31.9058 0.9000 1.76802 49.24 -0.0082 M-TAF101 *52 -251.0104 37.4794 53 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 54∞(BF) [Aspheric data] 52 pages K 0.00000 A4 -4.54607E-07 A6 2.33485E-09 A8 5.63788E-12 A10 -8.22774E-14 A12 2.45074E-16 [Various data] Zoom ratio 3.88 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 200.00 480.00 776.00 F-number 4.70 5.21 6.46 Full angle of view 2ω 12.07 5.05 3.12 Image height Y 21.63 21.63 21.63 Lens total length 360.00 410.00 470.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞3200.0000∞ (d8) 2.0000 2.0000 93.8698 (d11) 53.5563 53.5563 36.7465 (d21) 53.3750 53.3750 2.0000 (d30) 14.9669 14.9669 16.7107 (d37) 6.0514 2.7368 27.8252 (d40) 23.5806 26.8951 27.5602 (d47) 4.3431 4.3431 3.1608 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 3200.0000∞ 3200.0000 (d8) 93.8698 175.0342 175.0342 (d11) 36.7465 2.0565 2.0565 (d21) 2.0000 2.0000 2.0000 (d30) 16.7107 2.0000 2.0000 (d37) 10.6881 38.3157 10.1837 (d40) 44.6973 3.5000 31.6320 (d47) 3.1608 44.9669 44.9669 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 296.9228 G2 9 349.5032 G3 12 -43.8433 G4 22 144.9743 G5 31 200.0783 G6 38 104.8392 G7 41 -116.2129 G8 48 -129.5249 EXAMPLES

[0193] FIG. 101 is a lens configuration diagram of a variable magnification image forming optical system according to Example 11 when focusing on an object at infinity at the wide-angle end.

[0194] The variable magnification imaging optical system in Figure 101 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at close range, and a subsequent group GR consisting of a seventh lens group G7, an eighth lens group G8, and a ninth lens group G9 that move along the optical axis when focusing from an object at infinity to an object at close range.

[0195] Starting from the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with a convex surface facing the image side. The third lens group G3 is composed of a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the first to third lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a biconvex lens and a cemented lens of a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with a convex surface facing the image side. The seventh lens group G7 is composed of a convex meniscus lens with a convex surface facing the image side and a cemented lens of a biconcave lens. The eighth lens group G8 is composed of a concave meniscus lens with a convex surface facing the object side and a cemented lens of a biconvex lens and a biconcave lens. The ninth lens group G9 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with a convex surface facing the image side and a concave meniscus aspherical lens whose convex surface faces the image side and whose image side surface has a specified aspherical shape.

[0196] When changing magnification from the wide-angle end to the telephoto end, the ninth lens group G9 is fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 to the eighth lens group G8 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the distance between the third lens group G3 and the fourth lens group G4 decreases. However, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, the distance between the seventh lens group G7 and the eighth lens group G8 increases, and the distance between the eighth lens group G8 and the ninth lens group G9 increases, and when focusing from an object at infinity to an object at a close distance, the sixth lens group G6 moves toward the object side and the seventh lens group G7 moves toward the image side along the optical axis. Also, the amount of movement due to focusing from an object at infinity to the close distance end at the telephoto end is greater for the sixth lens group G6 than for the seventh lens group G7 (however, a comparison is made as a simple amount of movement without considering whether the movement is positive or negative depending on the direction of movement).

[0197] The values ​​of the specifications of the variable magnification imaging optical system according to the eleventh embodiment are shown below. Numerical Example 11 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 430.4436 3.0000 1.61310 44.36 -0.0081 E-ADF10 2 153.0257 0.1000 3 153.0275 8.8289 1.49700 81.54 0.0358 S-FPL51 4 -1334.9829 0.3000 5 145.1461 7.9542 1.43875 94.66 0.0560 S-FPL55 6 769.1863 (d6) 7 156.7769 8.4524 1.67300 38.26 -0.0038 S-NBH52V 8 -106.6504 1.6000 2.00069 25.46 0.0110 TAFD40-W 9 -232.2673 (d9) 10 9681.9688 1.0000 1.90525 35.04 -0.0005 S-LAH93 11 83.4849 4.0755 12 -69.6206 1.0000 1.76385 48.49 -0.0022 S-LAH96 13 64.8572 4.4249 1.85451 25.15 0.0071 NBFD25 14 -243.5612 3.4317 15 -103.9254 1.0000 1.77250 49.62 -0.0088 TAF1 16 68.8704 3.1445 1.85451 25.15 0.0071 NBFD25 17 177.8319 (d17) 18 186.5260 3.8381 1.64769 33.79 0.0063 S-TIM22 19 -122.3023 0.3000 20 74.2491 5.7819 1.43700 95.10 0.0564 FCD100 21 -71.9933 1.0000 1.77250 49.62 -0.0088 TAF1 22 -1965.5343 3.0000 23(Aperture) ∞ (d23) 24 52.8950 5.5913 1.43700 95.10 0.0564 FCD100 25 -143.8818 0.3000 26 41.4393 4.6221 1.49700 81.61 0.0373 FCD1 27 324.8839 1.0000 1.85451 25.15 0.0071 NBFD25 28 39.9899 (d28) 29 62.3571 5.0833 1.62004 36.26 0.0048 S-TIM2 30 -37.2181 0.9000 1.90525 35.04 -0.0005 S-LAH93 31 -107.4436 (d31) 32 -155.9203 3.4367 1.76182 26.61 0.0117 FD140 33 -38.9722 1.0000 1.76385 48.49 -0.0022 S-LAH96 34 90.9728 (d34) 35 6516.4207 1.0000 1.91082 35.25 -0.0028 TAFD35 36 29.0208 10.1977 1.74330 49.22 -0.0104 NBF1 37 -23.2861 1.0000 1.59282 68.62 0.0192 FCD515 38 59.5093 (d38) 39 45.7292 9.6411 1.61310 44.36 -0.0081 E-ADF10 40 -25.5828 1.0000 1.53775 74.70 0.0254 S-FPM3 41 -215.0370 8.9358 42 -29.8831 1.1999 1.85135 40.10 -0.0067 M-TAFD305 *43 -61.1541 35.6839 44 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 45∞(BF) [Aspheric data] 43 sides K 0.00000 A4 -8.13524E-07 A6 -3.67046E-09 A8 9.65368E-12 A10 -1.65331E-14 A12 0.00000E+00 [Various data] Zoom ratio 7.01 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 82.40 285.00 577.80 F-number 4.71 5.23 6.48 Full angle of view 2ω 29.82 8.52 4.18 Image height Y 21.63 21.63 21.63 Lens total length 290.00 345.69 400.25 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2500.0000∞ (d6) 2.0000 2.0000 99.0473 (d9) 16.6944 16.6944 21.5139 (d17) 68.1843 68.1843 17.5157 (d23) 16.3786 16.3786 4.4105 (d28) 16.9391 16.2225 18.4492 (d31) 2.6289 3.4454 14.0736 (d34) 8.8508 8.7508 4.2351 (d38) 2.0000 2.0000 10.1181 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2500.0000∞ 2500.0000 (d6) 99.0473 149.1147 149.1147 (d9) 21.5139 14.6944 14.6944 (d17) 17.5157 2.0000 2.0000 (d23) 4.4105 2.0000 2.0000 (d28) 12.3436 34.7722 22.7780 (d31) 21.7902 2.0000 23.8753 (d34) 2.6242 35.5910 25.7098 (d38) 10.1181 3.7511 3.7511 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 286.7602 G2 7 181.9090 G3 10 -33.3910 G4 18 94.5715 G5 24 203.2806 G6 29 93.7054 G7 32 -74.4126 G8 35 -108.2166 G9 39 132.2344 EXAMPLES

[0198] FIG. 111 is a lens configuration diagram of a variable magnification image forming optical system according to Example 12 when focusing on an object at infinity at the wide-angle end.

[0199] The variable magnification imaging optical system in Figure 111 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at close range, and a subsequent group GR consisting of a seventh lens group G7, an eighth lens group G8, and a ninth lens group G9 that move along the optical axis when focusing from an object at infinity to an object at close range.

[0200] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a convex meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a biconvex lens, a biconcave lens, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the second to fourth lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens of a concave meniscus lens with a convex surface facing the object side and a convex meniscus lens with a convex surface facing the object side, a biconvex lens, and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The seventh lens group G7 is composed of a convex meniscus lens with a convex surface facing the image side and a cemented lens of a biconcave lens. The eighth lens group G8 is composed of a concave meniscus lens with a convex surface facing the object side, and a cemented lens of a biconvex lens and a biconcave lens. The ninth lens group G9 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a concave meniscus lens with a convex surface facing the image side, and a concave meniscus aspherical lens whose convex surface faces the image side and whose image side surface has a specified aspherical shape.

[0201] When changing magnification from the wide-angle end to the telephoto end, the ninth lens group G9 is fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 to the eighth lens group G8 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the distance between the third lens group G3 and the fourth lens group G4 decreases. However, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, the distance between the seventh lens group G7 and the eighth lens group G8 increases, and the distance between the eighth lens group G8 and the ninth lens group G9 increases, and when focusing from an object at infinity to an object at a close distance, the sixth lens group G6 moves toward the object side and the seventh lens group G7 moves toward the image side along the optical axis. Also, the amount of movement due to focusing from an object at infinity to the close distance end at the telephoto end is greater for the sixth lens group G6 than for the seventh lens group G7 (however, a comparison is made as a simple amount of movement without considering whether the movement is positive or negative depending on the direction of movement).

[0202] The values ​​of the specifications of the variable magnification imaging optical system according to the twelfth embodiment are shown below. Numerical Example 12 Unit: mm [Face data] Surface number rd nd vd ΔPg Applicable glass material 0 (d0) 1 431.1270 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 181.9466 0.1000 3 180.1850 10.7003 1.49700 81.54 0.0358 S-FPL51 4 1479.9676 0.3000 5 347.7994 7.9768 1.43875 94.66 0.0560 S-FPL55 6 -3075.9801 0.3000 7 218.4111 7.9940 1.43875 94.66 0.0560 S-FPL55 8 762.3353 (d8) 9 187.2661 7.9232 1.90525 35.04 -0.0005 S-LAH93 10 -599.2238 1.9999 1.92286 20.88 0.0281 E-FDS1-W 11 522.7831 (d11) 12 315.1100 3.5012 1.84666 23.78 0.0136 FDS90-SG 13 -265.2081 2.5468 14 -217.7296 1.0000 1.90525 35.04 -0.0005 S-LAH93 15 77.9726 4.5386 16 -118.1366 1.0000 1.61772 49.81 0.0015 S-BSM28 17 56.2581 5.1605 1.85451 25.15 0.0071 NBFD25 18 -1987.3990 4.1802 19 -111.4815 1.0000 1.90525 35.04 -0.0005 S-LAH93 20 82.7212 3.9140 1.73800 32.33 -0.0002 S-NBH53V 21 2638.0233 (d21) 22 108.8250 4.3550 1.84666 23.78 0.0136 FDS90-SG 23 -218.2370 2.5000 24 59.3721 5.1718 1.49700 81.61 0.0373 FCD1 25 -325.6574 1.0000 1.80100 34.97 0.0009 S-LAM66 26 40.0887 0.6910 27 37.4470 8.5525 1.43700 95.10 0.0564 FCD100 28 -54.8675 1.0000 1.88300 40.80 -0.0094 TAFD30 29 -428.1340 3.0000 30(Aperture) ∞ (d30) 31 81.6569 1.0000 1.91082 35.25 -0.0028 TAFD35 32 37.6388 4.6711 1.43700 95.10 0.0564 FCD100 33 99.3214 0.3000 34 52.5577 6.7115 1.56732 42.84 0.0030 E-FL6 35 -80.7339 0.3000 36 96.1165 0.8997 1.85451 25.15 0.0071 NBFD25 37 50.9512 (d37) 38 60.7387 6.0297 1.72047 34.71 -0.0025 S-NBH8 39 -64.2703 0.8998 1.90525 35.04 -0.0005 S-LAH93 40 -1093.4038 (d40) 41 -2443.5531 5.5707 1.69895 30.05 0.0084 E-FD15L 42 -30.1155 1.0000 1.76385 48.49 -0.0022 S-LAH96 43 39.3188 (d43) 44 33.0380 1.0000 1.92286 20.88 0.0281 E-FDS1-W 45 23.1233 10.9939 1.61310 44.36 -0.0081 E-ADF10 46 -33.0619 0.9998 1.43700 95.10 0.0564 FCD100 47 49.1026 (d47) 48 -1271.4825 7.1200 1.61310 44.36 -0.0081 E-ADF10 49 -24.4175 1.0000 1.43700 95.10 0.0564 FCD100 50 -214.2543 5.8377 51 -31.3521 0.9000 1.85135 40.10 -0.0067 MC-TAFD305 *52 -89.1776 34.7439 53 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 54∞(BF) [Aspheric data] 52 pages K 0.00000 A4 -6.27946E-07 A6 1.41635E-09 A8 2.34641E-11 A10 -1.62795E-13 A12 3.65714E-16 [Various data] Zoom ratio 3.88 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 200.00 480.00 776.00 F-number 4.70 5.21 6.46 Full angle of view 2ω 12.05 5.06 3.12 Image height Y 21.63 21.63 21.63 Lens total length 359.00 410.00 470.00 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞3200.0000∞ (d8) 3.5552 3.5552 96.0943 (d11) 50.6835 50.6835 36.7990 (d21) 52.6303 52.6303 2.0000 (d30) 26.9278 26.9278 24.0712 (d37) 3.9763 2.4691 28.6302 (d40) 25.0430 28.0831 22.5285 (d43) 5.3755 3.8427 6.8031 (d47) 3.9249 3.9249 6.1903 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 3200.0000∞ 3200.0000 (d8) 96.0943 180.9445 180.9445 (d11) 36.7990 2.0000 2.0000 (d21) 2.0000 2.0000 2.0000 (d30) 24.0712 2.0000 2.0000 (d37) 13.9401 47.5622 22.9177 (d40) 38.2186 2.0000 29.1446 (d43) 5.8031 6.0000 3.4999 (d47) 6.1903 40.6099 40.6099 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 304.0603 G2 9 324.2267 G3 12 -46.1624 G4 22 152.3249 G5 31 227.1077 G6 38 101.0496 G7 41 -45.6301 G8 44 85.5463 G9 48 -128.171 EXAMPLES

[0203] FIG. 121 is a lens configuration diagram of a variable magnification image forming optical system according to Example 13 when focusing on infinity at the wide-angle end.

[0204] The variable magnification imaging optical system of Figure 121 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a first intermediate group GM1 consisting of a fourth lens group G4 and a fifth lens group G5, a second intermediate group GM2 consisting of a sixth lens group G6 that moves along the optical axis when focusing from an object at infinity to an object at close range, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0205] From the object side, the first lens group G1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconvex lens, and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 is composed of a biconvex lens, a concave meniscus lens with a convex surface facing the object side, a cemented lens of a biconcave lens and a biconvex lens, and a cemented lens of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. In addition, the second to fourth lenses from the object side of the third lens group G3 can be moved as a unit in a direction approximately perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a biconvex lens, a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side, and an aperture stop S. The fifth lens group G5 is composed of a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and a cemented lens of a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side. The sixth lens group G6 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a convex meniscus lens with a convex surface facing the image side and a biconcave lens, and a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens and a biconcave lens. The eighth lens group G8 is composed of a cemented lens of a biconvex lens and a biconcave lens, and a concave meniscus lens with a convex surface facing the image side.

[0206] When changing magnification from the wide-angle end to the telephoto end, the eighth lens group G8 is fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group G6 and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the object side along the optical axis.

[0207] The values ​​of the specifications of the variable magnification imaging optical system according to the thirteenth embodiment are shown below. Numerical Example 13 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 364.0187 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 144.4477 0.1006 3 146.2030 9.0089 1.49700 81.54 0.0358 S-FPL51 4 -1847.3364 0.3000 5 153.5443 8.6410 1.43875 94.66 0.0560 S-FPL55 6 2636.2840 (d6) 7 -126.4260 1.8000 1.84666 23.78 0.0136 FDS90-SG 8 616.6143 6.4528 1.67270 32.17 0.0058 E-FD5 9 -134.7347 0.3000 10 174.6621 6.3652 1.76634 35.83 -0.0046 S-NBH59 11 -245.7716 2.0500 1.59522 67.73 0.0177 S-FPM2 12 -683.3831 (d12) 13 621.2712 3.3627 1.84666 23.78 0.0136 FDS90-SG 14 -143.0480 2.5000 15 1123.6478 1.0000 1.80400 46.53 -0.0070 S-LAH65VS 16 73.5163 3.7404 17 -75.7910 1.0000 1.76385 48.49 -0.0022 S-LAH96 18 74.5979 3.9002 1.85451 25.15 0.0071 NBFD25 19 -383.8478 4.1736 20 -57.9235 1.0000 1.89190 37.13 -0.0035 S-LAH92 21 76.3910 3.2979 1.75520 27.53 0.0109 E-FD4L 22 485.1073 (d22) 23 245.1306 3.7431 1.59522 67.73 0.0177 S-FPM2 24 -105.4206 0.3000 25 82.3750 6.3133 1.43700 95.10 0.0564 FCD100 26 -49.5639 1.0000 1.77250 49.62 -0.0088 TAF1 27 -390.2942 3.0000 28(Aperture) ∞ (d28) 29 56.5846 1.0000 1.65160 58.54 -0.0041 S-LAL7Q 30 39.8104 10.1886 1.43700 95.10 0.0564 FCD100 31 -78.4544 1.5779 32 29.3661 3.0754 1.69930 51.11 -0.0012 S-LAL20 33 40.3977 0.8999 1.90110 27.06 0.0076 NBFD27 34 26.5305 (d34) 35 53.0578 5.1360 1.53172 48.84 0.0025 S-TIL6 36 -47.0988 0.9000 1.76385 48.49 -0.0022 S-LAH96 37 -148.7186 (d37) 38 -221.8563 3.7106 1.64769 33.79 0.0063 S-TIM22 39 -35.3782 1.0000 1.76385 48.49 -0.0022 S-LAH96 40 47.6910 10.6593 41 38.3514 0.9999 1.90525 35.04 -0.0005 S-LAH93 42 25.6168 11.0194 1.55298 55.07 -0.0046 J-KZFH4 43 -24.4628 1.0000 1.43700 95.10 0.0564 FCD100 44 47.3726 (d44) 45 96.4298 6.4202 1.76634 35.83 -0.0046 S-NBH59 46 -36.2920 0.9999 1.53775 74.70 0.0254 S-FPM3 47 177.4445 5.2193 48 -41.8822 0.9000 1.95375 32.32 0.0003 S-LAH98 49 -106.1830 36.7976 50 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 51 ∞ (BF) [Various data] Zoom ratio 3.74 Wide-angle (INF) Intermediate (INF) Telephoto (INF) Focal length 154.50 300.00 577.80 F-number 4.70 5.22 6.47 Full angle of view 2ω 15.66 8.06 4.18 Image height Y 21.63 21.63 21.63 Lens total length 295.00 355.13 397.86 [Variable interval data] Wide angle (INF) Wide angle (close distance) Intermediate (INF) (d0)∞2470.0000∞ (d6) 6.0877 6.0877 97.8049 (d12) 35.0780 35.0780 15.3742 (d22) 31.2854 31.2854 12.1804 (d28) 19.9943 19.9943 15.4517 (d34) 7.9084 5.4623 11.2681 (d37) 10.1812 12.6273 12.8265 (d44) 3.1115 3.1115 8.8668 (BF) 1.0000 1.0000 1.0000 Intermediate (close range) Telephoto (INF) Telephoto (close range) (d0) 2470.0000∞ 2470.0000 (d6) 97.8049 148.7388 148.7388 (d12) 15.3742 2.0000 2.0000 (d22) 12.1804 2.0000 2.0000 (d28) 15.4517 2.8817 2.8817 (d34) 3.8822 28.3467 8.5299 (d37) 20.2124 2.0000 21.8168 (d44) 8.8668 30.5356 30.5356 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 264.4733 G2 7 231.6391 G3 13 -34.4325 G4 23 113.3095 G5 29 110.8375 G6 35 97.9598 G7 38 -62.6019 G8 45 -783.9058

[0208] Below is a list of values ​​corresponding to the conditional expressions in each of the above embodiments. (The following is the corrected version.) Condition formula / Example EX1 EX2 EX3 EX4 EX5 (1) f1 / fT 0.4 0.4 0.5 0.5 0.4 (2) f2 / fT 0.23 0.33 0.75 0.44 0.25 (3) g2AXhW / g2AXhT 0.9 0.8 0.7 0.7 0.8 (4)(g2OAhw / Wih)-(g2OAhT / Tih) -0.6 -0.7 -0.8 -0.7 -0.9 (5) |g2OAhW / g2AXhT| 1.1 1.1 1.2 1.2 1.4 (6) DG1G2W / DG1G2T 0.108 0.041 0.075 0.096 0.122 (7) DG2G3W / DG2G3T 9.23 2.95 2.82 1.97 9.02 (8) DG1G2W / DG2G3W 0.76 0.18 0.27 0.46 0.92 (9) DG1G2T / DG2G3T 64.7 13.1 10.2 9.3 68.3 (10) ΔPgFLg2 0.0281 0.0327 0.0110 0.0281 0.0351 (11) f1 / fW 1.5 1.6 1.9 2.0 1.7 (12) f2 / fW 0.9 1.3 3.1 1.8 0.9 (13) DG2Sw / DG2St 1.6 1.5 1.7 1.6 1.8 (14) |fGM2 / fT| 0.19 0.22 0.12 0.12 0.18 (15) ΔPgFnLr 0.019 0.033 0.025 0.037 0.033 (16) νdnLr×ΔPgFnLr 1.32 0.89 1.90 3.04 0.89 (17) ΔPgFpLr -0.0054 -0.0054 -0.0081 -0.0094 -0.0030 (18) ΔPgFprAVE -0.0054 -0.0018 -0.0043 -0.0050 -0.0056 Horizontal / Dischargeable EX6 EX7 EX8 EX9 (1) f1 / fT 0.5 0.4 0.4 0.5 (2) f2 / fT 0.78 0.43 0.33 0.96 (3) g2AXhW / g2AXhT 0.7 1.0 0.9 0.5 (4)(g2OAhw / With)-(g2OAhT / Do) -0.8 -1.4 -1.1 -1.0 (5) |g2OAhW / g2AXhT| 1.2 1.7 1.6 1.6 (6) DG1G2W / DG1G2T 0.015 0.011 0.015 0.012 (7) DG2G3W / DG2G3T 1.81 29.33 12.57 9.78 (8) DG1G2W / DG2G3W 0.04 0.03 0.07 0.09 (9) DG1G2T / DG2G3T 5.1 89.1 57.4 68.1 (10) ΔPgFLg2 0.0351 0.0281 0.0192 0.0281 (11) f1 / fW 1.9 1.5 1.7 3.2 (12) f2 / fW 3.2 1.7 1.2 6.7 (13) DG2Sw / DG2St 1.6 3.0 2.3 2.9 (14) |fGM2 / fT| 0.15 0.14 0.15 0.14 (15) ΔPgFnLr 0.056 0.027 0.027 0.019 (16) νdnLr×ΔPgFnLr 5.30 2.07 2.07 1.32 (17) ΔPgFpLr -0.0081 -0.0054 -0.0054 -0.0081 (18) ΔPgFprAVE -0.0040 -0.0054 -0.0054 -0.0093 EX10 EX11 EX12 EX13 (1) f1 / fT 0.4 0.5 0.4 0.5 (2) f2 / fT 0.45 0.31 0.42 0.40 (3) g2AXhW / g2AXhT 0.9 0.4 0.9 0.8 (4)(g2OAhw / Wih)-(g2OAhT / Tih) -1.3 -0.9 -1.2 -1 (5) |g2OAhW / g2AXhT| 1.5 1.3 1.5 1.5 (6) DG1G2W / DG1G2T 0.011 0.013 0.020 0.041 (7) DG2G3W / DG2G3T 26.04 1.14 25.34 17.54 (8) DG1G2W / DG2G3W 0.04 0.12 0.07 0.17 (9) DG1G2T / DG2G3T 85.1 10.1 90.5 74.4 (10) ΔPgFLg2 0.0281 0.0110 0.0281 0.0177 (11) f1 / fW 1.5 3.5 1.5 1.7 (12) f2 / fW 1.7 2.2 1.6 1.5 (13) DG2Sw / DG2St 2.5 2.2 2.5 2.1 (14) |fGM2 / fT| 0.14 0.16 0.13 0.17 (15) ΔPgFnLr 0.056 0.025 0.056 0.025 (16) νdnLr×ΔPgFnLr 5.36 1.90 5.36 1.90 (17) ΔPgFpLr -0.0081 -0.0081 -0.0081 -0.0046 (18) ΔPgFprAVE -0.0068 -0.0093 -0.0081 -0.0046

[0209] <Other embodiments> The technology disclosed in this embodiment is not limited to the above-mentioned embodiment and the description of the embodiment, and various modifications are possible. The shapes and values ​​of each part shown in the above numerical examples are examples for implementing the present technology, and the technical scope of the present technology is not to be interpreted as being limited by them.

[0210] Furthermore, in the above-mentioned embodiment and example, a configuration including eight or nine lens groups has been described, but a configuration including lenses that have substantially no refractive power may also be used.

[0211] The present technology can also be configured as follows. [1] a first intermediate group GM1 consisting of one or more lens groups and including an aperture stop S; a second intermediate group GM2; and a subsequent group GR consisting of one or more lens groups, wherein a distance between adjacent lens groups changes during zooming or focusing, and when zooming from a wide-angle end to a telephoto end, the first lens group G1 moves toward the object side and the second lens group G2 is fixed with respect to an image plane, the distance between the first lens group G1 and the second lens group G2 increases and the distance between the second lens group G2 and the third lens group G3 decreases, and when focusing from an object at infinity to an object at a close distance, at least the second intermediate group GM2 moves along the optical axis. [2] In order from the object side, the first lens group G1 has a positive refractive power, the second lens group G2 has a positive refractive power, the third lens group G3 has a negative refractive power, the first intermediate group GM1 is made up of one or more lens groups and includes an aperture stop S, the second intermediate group GM2 is made up of one or more lens groups, a subsequent group GR, wherein a distance between adjacent lens groups changes during zooming or focusing, and during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the distance between the first lens group G1 and the second lens group G2 increases, and the third lens group G3 moves so that the distance between itself and the second lens group G2 decreases, and during focusing from an object at infinity to an object at a close distance, at least the second intermediate group GM2 moves along the optical axis. [3] The variable magnification imaging optical system according to [1] or [2], characterized in that the following conditional expression (1) is satisfied: (1) 0.2 <f1 / fT<1.0 f1: focal length of the first lens group G1 fT: focal length of the entire system at the infinity telephoto end [4] The variable magnification imaging optical system according to any one of [1] to [3], characterized in that the following conditional expression (2) is satisfied: (2) 0.10 <f2 / fT<1.40 f2: the focal length of the second lens group G2 fT: focal length of the entire system at the infinity telephoto end [5] The variable magnification imaging optical system according to any one of [1] to [4], wherein the second lens group G2 satisfies the following conditional expression (3): (3) 0.2 <g2AXhW / g2AXhT<1.5 g2AXhW: Height of the axial marginal ray at the front surface of the second lens group G2 at the infinity wide-angle end with the aperture fully open g2AXhT: Height of the axial marginal ray at the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open [6] The variable magnification imaging optical system according to any one of [1] to [5], wherein the second lens group G2 satisfies the following conditional expressions (4) and (5): (4)-1.8<(g2OAhW / Wih)―(g2OAhT / Tih)<-0.3 (5) 0.6<|g2OAhW / g2AXhT|<2.5 Wih: Maximum image height of the off-axis chief ray at the maximum angle of view at the wide-angle end at infinity Tih: Maximum image height of the off-axis chief ray at the maximum angle of view at the telephoto end at infinity g2OAhW: Height of the off-axis chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity wide-angle end g2OAhT: Height of the off-axis chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity telephoto end g2AXhT: Height of the axial marginal ray at the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open [7] The variable magnification imaging optical system according to any one of [1] to [6], characterized in that the following conditional expression (6) is satisfied: (6) 0.005 <DG1G2W / DG1G2T<0.400 DG1G2W: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity wide-angle end DG1G2T: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity telephoto end [8] The variable magnification imaging optical system according to any one of [1] to [7], characterized in that the following conditional expression (7) is satisfied: (7)1.0 <DG2G3W / DG2G3T<80.0 DG2G3W: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end DG2G3T: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity telephoto end [9] The variable magnification imaging optical system according to any one of [1] to [8], wherein the following conditional expression (8) is satisfied: (8) 0.01 <DG1G2W / DG2G3W<2.00 DG1G2W: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity wide-angle end DG2G3W: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end

[10] The variable magnification imaging optical system according to any one of [1] to [9], wherein the following conditional expression (9) is satisfied: (9)2.0 <DG1G2T / DG2G3T<200.0 DG1G2T: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity telephoto end DG2G3T: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity telephoto end

[11] The variable magnification imaging optical system according to any one of [1] to

[10] , wherein the second lens group G2 includes one or more concave lenses.

[12] The variable magnification imaging optical system according to any one of [1] to

[11] , wherein the second lens group G2 includes at least one concave lens that satisfies the following conditional expression (10): (10)ΔPgFLg2>0.0090 ΔPgFLg2: Anomalous dispersion of the concave lens having the largest anomalous dispersion among the concave lenses included in the second lens group G2

[13] The variable magnification imaging optical system according to any one of [1] to

[12] , wherein the following conditional expression (11) is satisfied: (11)1.0 <f1 / fW<5.0 f1: focal length of the first lens group G1 fW: focal length of the entire system at the wide-angle end at infinity

[14] The variable magnification imaging optical system according to any one of [1] to

[13] , wherein the following conditional expression (12) is satisfied: (12)0.5 <f2 / fW<8.5 f2: the focal length of the second lens group G2 fW: focal length of the entire system at the wide-angle end at infinity

[15] 3. The variable magnification imaging optical system according to claim 1, wherein the following conditional expression (13) is satisfied: (13)1.2 <DG2Sw / DG2St<5.0 DG2Sw: the distance from the apex of the object side of the lens closest to the object in the second lens group G2 at the wide-angle end to the aperture stop S DG2St: the distance from the apex of the object side of the lens closest to the object in the second lens group G2 at the telephoto end to the aperture stop S

[16] The second intermediate group GM2 is a group that moves the largest amount of movement from infinity at the telephoto end to the closest object among groups that move in the optical axis direction during focusing from an object at infinity to an object at a close distance, and is characterized in satisfying the following conditional formula (14). (14) 0.05<|fGM2 / fT|<0.40 fGM2: focal length of the second intermediate group fT: focal length of the entire system at the infinity telephoto end

[17] The variable magnification imaging optical system described in any one of [1] to

[16] , characterized in that the lens group closest to the image side among the lens groups constituting the rear group GR includes at least one concave lens that satisfies the following conditional expression (15): (15) ΔPgFnLr>0.009 ΔPgFnLr: Anomalous dispersion of the concave lens in the subsequent group

[18] The variable magnification imaging optical system described in any one of [1] to

[17] , characterized in that the lens group closest to the image side among the lens groups constituting the rear group GR includes at least one concave lens that satisfies the following conditional expression (16): (16) 0.8 0<νdnLr×ΔPgFnLr νdnLr: Abbe number of the concave lens in the subsequent group ΔPgFnLr: Anomalous dispersion of the concave lens in the subsequent group

[19] The variable magnification imaging optical system described in any one of [1] to

[18] , characterized in that the lens group closest to the image side among the lens groups constituting the rear group GR includes at least one convex lens that satisfies the following conditional expression (17): (17)ΔPgFpLr<-0.0010 ΔPgFpLr: Anomalous dispersion of the convex lens in the rear group GR

[20] The variable magnification imaging optical system according to any one of [1] to

[19] , wherein the two convex lenses counted from the image side satisfy the following conditional expression (18): (18)ΔPgFprAVE<-0.0010 ΔPgFprAVE: Average value of anomalous dispersion of the two convex lenses closest to the image side [twenty one] The variable magnification imaging optical system according to any one of [1] to

[20] , wherein the lens group arranged closest to the image side among the subsequent lens groups GR is fixed with respect to the image plane when changing magnification from the wide-angle end to the telephoto end.

[0212] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur to those skilled in the art depending on design requirements and other factors, and they are intended to be within the scope of the appended claims and their equivalents. [Explanation of symbols]

[0213] G1 First lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group G8 8th lens group G9 9th lens group GM1 1st intermediate group GM2 2nd intermediate group GR Successor Group S aperture stop F Filter I image plane

Claims

1. a first intermediate group GM1 consisting of one or more lens groups and including an aperture stop S, a second intermediate group GM2, and a subsequent group GR consisting of one or more lens groups, wherein a distance between adjacent lens groups changes during zooming or focusing, and when zooming from a wide-angle end to a telephoto end, the first lens group G1 moves toward the object side and the second lens group G2 is fixed with respect to an image plane, the distance between the first lens group G1 and the second lens group G2 increases and the distance between the second lens group G2 and the third lens group G3 decreases, and when focusing from an object at infinity to an object at a close distance, at least the second intermediate group GM2 moves along the optical axis.

2. In order from the object side, there are a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a first intermediate group GM1 consisting of one or more lens groups and including an aperture stop S, a second intermediate group GM2, and a second intermediate group GM3 consisting of one or more lens groups. a first intermediate group GM2 and a second intermediate group GR, the distance between adjacent lens groups changing during zooming or focusing, when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the distance between the first lens group G1 and the second lens group G2 increases, and the third lens group G3 moves so that the distance between itself and the second lens group G2 decreases, and when focusing from an object at infinity to an object at a close distance, at least the second intermediate group GM2 moves along the optical axis.

3. 3. The variable magnification imaging optical system according to claim 1, wherein the following conditional expression (1) is satisfied: (1) 0.2<f1 / fT<1.0 f1: focal length of the first lens group G1 fT: focal length of the entire system at the infinity telephoto end

4. 3. The variable magnification imaging optical system according to claim 1, wherein the following conditional expression (2) is satisfied: (2) 0.10<f2 / fT<1.40 f2: focal length of the second lens group G2 fT: focal length of the entire system at the infinity telephoto end

5. 3. The variable magnification image forming optical system according to claim 1, wherein the second lens group G2 satisfies the following conditional expression (3): (3) 0.2<g2AXhW / g2AXhT<1.5 g2AXhW: Height of the axial marginal ray on the front surface of the second lens group G2 at the infinity wide-angle end with the aperture fully open g2AXhT: Height of the axial marginal ray on the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open

6. 3. The variable magnification image forming optical system according to claim 1, wherein the second lens group G2 satisfies the following conditional expressions (4) and (5): (4) -1.8<(g2OAhW / Wih)-(g2OAhT / Tih)<-0.3 (5) 0.6<|g2OAhW / g2AXhT|<2.5 Wih: maximum image height of the off-axis chief ray at the maximum angle of view at the wide-angle end at infinity Tih: maximum image height of the off-axis chief ray at the maximum angle of view at the telephoto end at infinity g2OAhW: Height of the off-axis chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity wide-angle end g2OAhT: Height of the off-axis chief ray at the maximum angle of view on the front surface of the second lens group G2 at the infinity telephoto end g2AXhT: Height of the axial marginal ray on the front surface of the second lens group G2 at the infinity telephoto end with the aperture fully open

7. 3. The variable magnification imaging optical system according to claim 1, wherein the following condition (6) is satisfied: (6) 0.005<DG1G2W / DG1G2T<0.400 DG1G2W: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity wide-angle end DG1G2T: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity telephoto end

8. 3. The variable magnification imaging optical system according to claim 1, wherein the following condition (7) is satisfied: (7) 1.0<DG2G3W / DG2G3T<80.0 DG2G3W: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end DG2G3T: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity telephoto end

9. 3. The variable magnification imaging optical system according to claim 1, wherein the following condition (8) is satisfied: (8) 0.01<DG1G2W / DG2G3W<2.00 DG1G2W: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity wide-angle end DG2G3W: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end

10. 3. The variable magnification imaging optical system according to claim 1, wherein the following condition (9) is satisfied: (9) 2.0<DG1G2T / DG2G3T<200.0 DG1G2T: the distance on the optical axis between the first lens group G1 and the second lens group G2 at the infinity telephoto end DG2G3T: the distance on the optical axis between the second lens group G2 and the third lens group G3 at the infinity telephoto end

11. 3. The variable magnification imaging optical system according to claim 1, wherein the second lens group G2 includes one or more concave lenses.

12. 3. The variable magnification image forming optical system according to claim 1, wherein the second lens group G2 includes at least one concave lens that satisfies the following conditional expression (10): ##EQU10## (10)ΔPgFLg2>0.0090 ΔPgFLg2: anomalous dispersion of the concave lens having the largest anomalous dispersion among the concave lenses included in the second lens group G2

13. 3. The variable magnification imaging optical system according to claim 1, wherein the following condition (11) is satisfied: (11) 1.0<f1 / fW<5.0 f1: focal length of the first lens group G1 fW: focal length of the entire system at the wide-angle end at infinity

14. 3. The variable magnification imaging optical system according to claim 1, wherein the following condition (12) is satisfied: (12) 0.5<f2 / fW<8.5 f2: focal length of the second lens group G2 fW: focal length of the entire system at the wide-angle end at infinity

15. 3. The variable magnification imaging optical system according to claim 1, wherein the following condition (13) is satisfied: (13) 1.2<DG2Sw / DG2St<5.0 DG2Sw: the distance from the apex of the object side of the lens closest to the object side in the second lens group G2 at the wide-angle end to the aperture stop S DG2St: the distance from the apex of the object side of the lens closest to the object side in the second lens group G2 at the telephoto end to the aperture stop S

16. 3. The variable magnification imaging optical system according to claim 1, wherein the second intermediate group GM2 is a group that moves the largest amount of movement from infinity at the telephoto end to the closest object among groups that move in the optical axis direction during focusing from an object at infinity to an object at a close distance, and satisfies the following conditional expression (14): (14) 0.05<|fGM2 / fT|<0.40 fGM2: the focal length of the second intermediate group fT: focal length of the entire system at the infinity telephoto end

17. 3. The variable magnification imaging optical system according to claim 1, wherein the lens group closest to the image side among the lens groups constituting the rear group GR includes at least one concave lens that satisfies the following condition (15): (15)ΔPgFnLr>0.009 ΔPgFnLr: Anomalous dispersion of the concave lens in the subsequent group

18. 3. The variable magnification imaging optical system according to claim 1, wherein the lens group closest to the image side among the lens groups constituting the rear group GR includes at least one concave lens that satisfies the following condition (16): (16) 0.80<νdnLr×ΔPgFnLr νdnLr: Abbe number of the concave lens in the subsequent group ΔPgFnLr: Anomalous dispersion of the concave lens in the subsequent group

19. 3. The variable magnification imaging optical system according to claim 1, wherein the lens group closest to the image side among the lens groups constituting the rear group GR includes at least one convex lens that satisfies the following condition (17): (17) ΔPgFpLr<-0.0010 ΔPgFpLr: Anomalous dispersion of the convex lens of the rear group GR

20. 3. The variable magnification image forming optical system according to claim 1, wherein the two convex lenses counted from the image side satisfy the following conditional expression (18): (18)ΔPgFprAVE<-0.0010 ΔPgFprAVE: Average value of anomalous dispersion of the two convex lenses closest to the image side

21. 3. The variable magnification imaging optical system according to claim 1, wherein the lens group arranged closest to the image side among said rear group GR is fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.

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