Zoom imaging optical system

Abstract

To provide a compact and lightweight zoom imaging optical system with excellent optical performance across the entire zoom range, which has focusing that suppresses lateral chromatic aberration during zooming, and suppresses acceleration and performance degradation during focusing.SOLUTION: The zoom imaging optical system includes in order from the object side, 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, an intermediate group GM consisting of one or more lens groups and including an aperture stop S, a focusing group GF having a positive refractive power, and a subsequent group GR consisting of two or more lens groups. The focusing group GF has one or more concave lenses that satisfy a certain conditional formula. The lens group closest to the image side among the lens groups consisting of the subsequent group GR includes at least one or more concave lenses that satisfy the certain conditional formula. A distance between the adjacent lens groups is varied during zooming or focusing. The focusing group GF is moved along an optical axi when focusing from an object at an infinite distance to an object at a short distance.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 3 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] Patent Publication No. 2013-167749 [Patent Document 2] Patent Publication No. 2016-080825 [Patent Document 3] Patent Publication No. 2019-020450 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] 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 attempts to increase the zoom ratio while maintaining imaging performance with a type of lens with a fixed overall length like this, the optical system would become significantly larger, which is not desirable.

[0010] 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.

[0011] 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.

[0012] 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 when zooming, has high-speed focusing with reduced performance degradation, and has good optical performance over the entire zoom range. [Means for solving the problem]

[0013] 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 middle lens group GM consisting of one or more lens groups and including an aperture stop S, a focusing group GF having positive refractive power, and a subsequent group GR consisting of two or more lens groups, wherein the focusing group GF has one or more concave lenses that satisfy conditional expression (7), and the lens group closest to the image side among the lens groups constituting the subsequent group GR includes at least one or more concave lenses that satisfy conditional expression (9) below, a distance between adjacent lens groups changes during magnification or focusing, and the focusing group GF moves along the optical axis during focusing from an object at infinity to an object at a close distance. (7) ΔPgFLf>0.013 ΔPgFLf: Anomalous dispersion of the concave lens constituting the focusing group GF (9) 1.0<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

[0014] A variable magnification image forming optical system embodying the present invention further 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 middle group GM consisting of one or more lens groups and including an aperture stop S, a focusing group GF having positive refractive power, and a subsequent group GR consisting of two or more lens groups, wherein the focusing group GF has one or more concave lenses that satisfy conditional formula (7) and satisfies conditional formula (10), the spacing between adjacent lens groups changes during magnification or focusing, and the focusing group GF moves along the optical axis during focusing from an object at infinity to an object at a close distance. (7) ΔPgFLf>0.013 ΔPgFLf: Anomalous dispersion of the concave lens constituting the focusing group GF (10) ΔPgFprAVE<-0.0035 ΔPgFprAVE: The average value of the anomalous dispersion of the two convex lenses that make up the rear lens group GR, located closest to the image side Effect of the Invention

[0015] According to the present invention, a variable magnification imaging optical system can be obtained that is compact and lightweight, suppresses chromatic aberration of magnification when zooming, has high-speed focusing and suppresses performance degradation when focusing, and has good optical performance over the entire zoom range. [Brief description of the drawings]

[0016] [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] 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 telephoto end. FIG. [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] 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 9] 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 10] 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 11] 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 12] 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 13] 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 14] 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 15] 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 16] 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 17] 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 18] 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. [Figure 19] 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 20]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 21] 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 22] 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 23] 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. [Figure 24] 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 25] 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. [Figure 26] 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. [Figure 27] 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 28] 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 29] 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 30] 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 31] 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 32] 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 33] 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. [Diagram 34] 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. [Diagram 35]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. [Diagram 36] 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 37] 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 38] 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 39] 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. [Diagram 40] 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. [Diagram 41] FIG. 13 is a lateral aberration diagram of Example 6 of the variable magnification image forming optical system of the present invention when focusing on an object at infinity at an intermediate focal length. [Diagram 42] 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. [Diagram 43] 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. [Diagram 44] 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. [Diagram 45] 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. [Diagram 46] 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 47] 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 48] 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 optical system is focused on an object at infinity at an intermediate focal length. [Figure 49] 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 50]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 infinity at the wide-angle end. [Figure 51] 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 52] 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. [Diagram 53] 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 54] 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 55] 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 56] 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 57] 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 an object at infinity at the wide-angle end. [Figure 58] 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 59] 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 60] 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 61] 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 62] 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 63] 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 64] 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 65]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 66] 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 67] 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 68] 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 69] 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 70] 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 71] 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 72] 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 73] 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 74] 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 75] 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. [Figure 76] 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 77] 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 78] 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 79] 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 80]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. [Figure 81] 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 82] 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. [Figure 83] 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 84] 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. [Figure 85] FIG. 23 is a lens configuration diagram of a variable magnification image forming optical system according to a thirteenth embodiment of the present invention when focusing on an object at infinity at the wide-angle end. [Figure 86] 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 87] 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 88] 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. [Figure 89] 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. [Figure 90] 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 91] 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 92] FIG. 23 is a lens configuration diagram of a variable magnification image forming optical system according to a fourteenth embodiment of the present invention when focusing 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 14 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 94] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 14 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 95]FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 14 of the present invention when focused on an object at infinity at the telephoto end. [Figure 96] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 14 of the present invention when focused on an object at infinity at the wide-angle end. [Figure 97] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 14 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 98] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 14 of the present invention when focused on an object at infinity at the telephoto end. [Figure 99] FIG. 23 is a lens configuration diagram of a variable magnification image forming optical system according to a fifteenth embodiment of the present invention when focusing on an object at infinity at the wide-angle end. [Figure 100] FIG. 23 is a longitudinal aberration diagram of the fifteenth embodiment 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 101] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 15 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 102] FIG. 23 is a longitudinal aberration diagram of the variable magnification image forming optical system according to Example 15 of the present invention when focused on an object at infinity at the telephoto end. [Figure 103] FIG. 23 is a lateral aberration diagram of the fifteenth embodiment 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 104] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 15 of the present invention when the intermediate focal length is focused on an object at infinity. [Figure 105] FIG. 23 is a lateral aberration diagram of the variable magnification image forming optical system according to Example 15 of the present invention when focused on an object at infinity at the telephoto end. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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.

[0018] 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 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:

[0019] 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.

[0020] 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:

[0021] 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: Axial ray height hb: Off-axis chief ray height φ: Refractive power ν: Abbe number The chief ray is defined as a ray that passes through the point where the diaphragm surface and the optical axis intersect.

[0022] 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 as the magnification changes from the wide-angle end to the telephoto end, widening the distance between the first lens group G1 and the aperture stop S, lateral chromatic aberration 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, in order to reduce lateral chromatic aberration across all wavelengths, a method is often used in which the g-line and C-line are collected, and in such a case, if there is a large difference in the imaging magnification between the g-line and C-line and other wavelengths, undesirable color bleeding such as reddish purple appears on the contours of the subject as a secondary spectrum.

[0023] 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.

[0024] 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.

[0025] As can be seen from the numerical examples and the configuration diagrams of the examples, the variable magnification imaging optical system of the present invention is composed of, in order from the object side, 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, an intermediate group GM consisting of one or more lens groups and including an aperture stop S, a focusing group GF, and a subsequent group GR consisting of one or more lens groups, and when varying magnification or focusing, the interval 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, the second lens group G2 moves toward the image side, the interval between the first lens group G1 and the second lens group G2 increases, and the interval between the second lens group G2 and the third lens group G3 decreases, thereby obtaining the main variable magnification effect of the variable magnification imaging optical system. When focusing from an object at infinity to an object at a close distance, the focusing group GF moves along the optical axis.

[0026] The second lens group G2, which has positive refractive power, moves toward the image side with respect to the image plane when zooming from the wide-angle end to the telephoto end, changing the off-axis chief ray that passes through a high position at the wide-angle end so that it passes 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.

[0027] Furthermore, if glass with positive anomalous dispersion is used for the concave lens and glass with negative anomalous dispersion is used for the convex lens in the second lens group G2, or both, it will be possible to correct the g-line in the under direction on the wide-angle side, making it easier to correct lateral chromatic aberration.

[0028] The intermediate group GM, which is made up of one or more lens groups and includes an aperture diaphragm S, has the effect of converging the light beam diverged by the third lens group G3 and of controlling the height of the light rays entering the focusing group GF to an appropriate height. This not only contributes to reducing the weight of the focusing group GF, but also plays a role in compensating the image surface during zooming.

[0029] The focusing group GF moves along the optical axis when focusing from an object at infinity to a close object, correcting shifts in the image position when the object distance changes.

[0030] The following group GR, which is made up of one or more lens groups, is responsible for image plane compensation as well as correcting the lateral chromatic aberration that becomes significant at the telephoto end. By using glass with positive anomalous dispersion for the concave lenses in the following group GR and glass 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. Furthermore, in the following group GR, axial rays pass through at a lower ray height than off-axis chief rays, and so the correction effect of lateral chromatic aberration tends to become greater at higher image heights.

[0031] On the other hand, if the lateral chromatic aberration on the telephoto side is corrected by using glass with positive anomalous dispersion for the concave lens and glass with negative anomalous dispersion for the convex lens 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 across the entire range from the wide-angle end to the telephoto end.

[0032] 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

[0033] 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 to the focal length of the first lens group at the infinity telephoto end and indicates a desirable range for shortening the overall length of the optical system and reducing the weight of the lens barrel.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Similarly, in the variable magnification image-forming 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) 0.1 <f2 / fT<0.8 f2: the focal length of the second lens group G2 fT: focal length of the entire system at the infinity telephoto end

[0038] 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.

[0039] 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 refractive power will be insufficient, making it difficult to shorten the overall length of the optical system. Furthermore, if one tries to forcibly shorten the overall length and compensates for the insufficient refractive power 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 achieve high performance.

[0040] 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.

[0041] In addition, it is preferable to set the lower limit of condition (2) to 0.2 and the upper limit to 0.6, so that the above-mentioned effect can be ensured more reliably.

[0042] 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 realize effective correction of lateral chromatic aberration over the entire zoom range. (3)1.3 <DG2Sw / DG2St<3.2 DG2Sw: the distance from the apex of the lens closest to the object in the second lens group G2 to the aperture at the wide-angle end DG2St: the distance from the apex of the lens closest to the object in the second lens group G2 to the aperture at the telephoto end

[0043] Conditional formula (3) that the variable magnification imaging optical system of the present invention must satisfy defines a desirable range for the ratio of the distance from the apex of the surface 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 middle group GM. 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.

[0044] If the lower limit of conditional formula (3) is exceeded and the ratio between the distance from the apex of the surface of the lens in the second lens group G2 closest to the object to the aperture stop S at the wide-angle end and the telephoto end becomes small, the change in the off-axis chief ray passing through the second lens group G2 becomes small, and the change in the correction effect of the lateral chromatic aberration becomes small, which makes it difficult to effectively correct the lateral chromatic aberration over the entire zoom range, which is not preferable.

[0045] If the upper limit of conditional expression (3) is exceeded and the ratio between the distance from the apex of the surface of the lens in the second lens group G2 closest to the object to the aperture at the wide-angle end and the telephoto end becomes large, the amount of movement of the second lens group G2 due to magnification change will become large, and the off-axial light beam at the wide-angle end will pass through a higher spot, which is undesirable as it leads to an increase in the outer diameter of the second lens group G2.

[0046] As for condition (3), it is preferable to set the lower limit to 1.4 and the upper limit to 2.6, so that the above-mentioned effect can be ensured more reliably.

[0047] In the variable magnification imaging optical system of the present invention, the second lens group G2, in which the ray height of the off-axial chief ray changes significantly 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)-0.3>(g2hrW / Wih)-(g2hrT / Tih)>-1.5 (5) ΔPgFLg2>0.013 g2hrW: Height of the off-axis chief ray on the front surface of the second lens group G2 at the infinity wide-angle end g2hrT: Height of the off-axis chief ray on the front surface of the second lens group G2 at the infinity telephoto end The off-axis chief ray is defined as a ray that passes through the point where the aperture position and the optical axis intersect. Width: Ray height on the image plane of the off-axis chief ray at the wide-angle end Tih: ray height on the image plane of the off-axis chief ray at the telephoto end ΔPgFLg2: Anomalous dispersion of the concave lens having the largest anomalous dispersion among the concave lenses included in the second lens group G2

[0048] Conditional formula (4) specifies a desirable range for the difference between the ratio of the height of the off-axial chief ray on the front 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 same wide-angle end, and the ratio of the height of the off-axial chief ray on the front 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 same 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.

[0049] 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 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 wide-angle end, and the ratio of the height of the off-axial chief ray 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 telephoto end, becomes large and 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 becomes small, the correction effect of the lateral chromatic aberration becomes small, and the lateral chromatic aberration cannot be sufficiently corrected either on the wide-angle side or the telephoto side, which is not preferable.

[0050] If the lower limit of conditional expression (4) is exceeded and the difference between the ratio of the height of the off-axial chief ray 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 wide-angle end, and the ratio of the height of the off-axial chief ray 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 telephoto end, decreases away from 0, 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 becomes too large, which is undesirable as it makes it difficult to correct astigmatism and field curvature.

[0051] As for condition (4), it is preferable to set the lower limit to -1.3 and the upper limit to -0.4, so that the above-mentioned effect can be ensured.

[0052] Condition (5) 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.

[0053] 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 greater positive anomalous dispersion are advantageous for correcting the g-line.

[0054] If the anomalous dispersion becomes small beyond the lower limit of condition (5), 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.

[0055] With regard to condition (5), it is preferable to set the upper limit to 0.018, and more preferably 0.020, so that the above-mentioned effect can be ensured.

[0056] In the variable magnification imaging optical system of the present invention, it is desirable to satisfy the following conditional expression (6) in order to achieve both a reduction in the overall length of the optical system and high performance. (6)1.0 <f1 / fW<2.5 f1: focal length of the first lens group G1 fW: focal length of the entire system at the wide-angle end at infinity

[0057] Conditional expression (6) 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.

[0058] If the upper limit of condition (6) 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 power of the first lens group G1 becomes insufficient, making it difficult to shorten the overall length of the optical system, which is undesirable.

[0059] If the lower limit of condition (6) 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 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 thus making it difficult to achieve high performance, which is not preferable.

[0060] As for condition (6), it is preferable to set the upper limit to 1.9 and the lower limit to 1.3, so that the above-mentioned effect can be ensured more reliably.

[0061] In the variable magnification image forming optical system of the present invention, the third lens group G3 is fixed relative to the image plane during magnification change to prevent the mechanism from becoming complicated. This is preferable because in the case where a part of the third lens group G3 is moved in a direction approximately perpendicular to the optical axis to serve as an image stabilization group, the mechanism can be simplified because the drive unit and wiring do not move during magnification change.

[0062] As can be seen from the numerical examples and the configuration diagrams of each example, the variable magnification imaging optical system of the present invention comprises 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, an intermediate group GM consisting of one or more lens groups and including an aperture stop S, a focusing group GF having positive refractive power, and a subsequent group GR consisting of one or more lens groups, and is an optical system characterized in that the spacing between adjacent lens groups changes when varying magnification, and that the focusing group GF moves along the optical axis when focusing from an object at infinity to an object at a close distance.

[0063] In the variable magnification image forming optical system of the present invention, in order to correct lateral chromatic aberration over the entire zoom range and achieve high performance, it is desirable for the focusing group GF to include at least one concave lens that satisfies conditional expression (7). 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. (7) ΔPgFLf>0.013 ΔPgFLf: Anomalous dispersion of the concave lens that constitutes the focusing group GF

[0064] Condition (7) defines the range of anomalous dispersion of the concave lens that is desirably included in the focusing group GF at least one lens. In the variable power optical system of the present invention, the imaging magnification of light rays with short wavelengths, particularly those with wavelengths shorter than the g-line, decreases on the telephoto side, and lateral chromatic aberration in the under-focus direction remains. To effectively correct this, it is desirable to use a lens with large ΔPgF and large positive anomalous dispersion for the concave lens in the group behind the aperture stop S.

[0065] If the lower limit of condition (7) is exceeded and the anomalous dispersion of the concave lenses in the focusing group GF becomes small, the effect of over-correcting the g-line at peripheral image heights on the telephoto side becomes smaller, making it difficult to correct lateral chromatic aberration throughout the entire zoom range.

[0066] With regard to the lower limit of condition (7), it is preferable to set the lower limit at 0.018, and more preferably at 0.020, in order to ensure the above-mentioned effect.

[0067] In a variable magnification image forming optical system of this invention, in order to efficiently correct lateral chromatic aberration with a concave lens in the focusing group GF, it is desirable for the off-axis chief ray to pass through a higher position, and therefore it is best to place a concave lens that has a large ΔPgF and large positive anomalous dispersion and is effective in correcting lateral chromatic aberration, as far away as possible from the aperture stop S.

[0068] In the variable magnification image-forming optical system of the present invention, it is desirable to satisfy the following condition (8). (8) 0.08 <fF / fT<0.25 fF: focal length of the focusing group GF fT: focal length of the entire system at the infinity telephoto end

[0069] A shorter movement distance of the focusing group GF from infinity to the close range has the advantage of improving focusing speed, but it requires strengthening the power of the focusing group GF, which results in a large degradation in performance during focusing, and is not desirable. With this in mind, conditional formula (8) prescribes a preferable range for the ratio of the focal length of the focusing group GF to the focal length of the entire system at the infinity / telephoto end, in order to increase focusing speed and suppress degradation in performance during focusing.

[0070] If the lower limit of condition (8) is exceeded and the ratio of the focal length of the focusing group GF to the focal length of the entire system at the infinity to telephoto end becomes small, the power of the focusing group GF will be insufficient, the moving distance of the focusing group GF from infinity to the close range side will become long, and this will result in a decrease in focusing speed, which is not desirable.

[0071] If the upper limit of condition (8) is exceeded and the ratio of the focal length of the focusing group GF to the focal length of the entire system at the infinity telephoto end becomes large, the power of the focusing group GF will become too strong, causing large fluctuations in performance due to the deterioration of various aberrations during focusing, which is undesirable.

[0072] As for condition (8), it is preferable to set the lower limit to 0.10 and the upper limit to 0.20, so that the above-mentioned effect can be more reliably achieved.

[0073] 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 (9): Note that the concave lens shown here may be either a single lens or a concave lens arranged as part of a cemented lens. (9) 1.0<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

[0074] Conditional formula (9) 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 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 the remaining lateral chromatic aberration in the under direction. To effectively correct this, it is desirable to use a lens with a large ΔPgF and large positive anomalous dispersion for the concave lens in the group behind the aperture stop S.

[0075] If the lower limit of condition (9) 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.

[0076] With regard to the lower limit of condition (9), it is preferable to set the lower limit at 1.3, and more preferably at 1.8, in order to ensure the above-mentioned effect.

[0077] 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 lenses closest to the image side among those constituting the rear group GR satisfy the range of conditional expression (10). Note that the convex lens shown here may be either a single lens or a convex lens arranged as part of a cemented lens. (10) ΔPgFprAVE<-0.0035 ΔPgFprAVE: The average value of the anomalous dispersion of the two convex lenses that make up the rear lens group GR, located closest to the image side

[0078] Conditional formula (10) specifies the average value of the anomalous dispersion of the two convex lenses closest to the image side that make up the subsequent group GR of 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, leaving lateral chromatic aberration in the under-focus direction. To effectively correct this, it is desirable to use lenses with small ΔPgF and large negative anomalous dispersion for the convex lenses in the group behind the aperture stop S.

[0079] If the upper limit of condition (10) 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.

[0080] Incidentally, with regard to condition (10), it is preferable to set the upper limit to −0.0050, so that the above-mentioned effect can be ensured more reliably.

[0081] In the variable magnification image-forming optical system of the present invention, in order to ensure the overcorrection of g-line by the succeeding group GR on the telephoto side, it is necessary to keep the height of the peripheral light flux passing through the second lens group G2, which has the effect of correcting g-line in the undercorrection, low on the telephoto side, and for this purpose, when changing magnification from the wide-angle end to the telephoto end, the second lens group G2 needs to move closer to the lens groups after the third lens group G3. Therefore, when changing magnification from the wide-angle end to the telephoto end, it is desirable that 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 distance between the second lens group G2 and the third lens group G3 decreases.

[0082] 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.

[0083] Next, the lens configuration of an embodiment of the variable magnification imaging optical system of the present invention will be described below. Note that in the following description, the lens configuration will be described in order from the object side to the image side.

[0084] 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].

[0085] 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.

[0086] The (stop) next to the 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).

[0087] [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 4th, 6th, 8th, and 10th order aspheric coefficients are represented by A4, A6, A8, and A10, respectively. TIFF2024177501000002.tif18124

[0088] [Various Data] shows values ​​such as focal length at each shooting distance and focus state.

[0089] [Variable Distance Data] shows the variable distance and BF values ​​at various shooting distances and focusing conditions.

[0090] [Lens Group Data] shows the lens numbers of the lens groups closest to the object and the composite focal length of the entire group.

[0091] 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. 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. EXAMPLES

[0092] 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.

[0093] The variable magnification image-forming 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0094] Starting from the object side, the first lens group G1 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 convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a biconvex aspheric lens, and a cemented lens of a biconvex lens and a biconcave lens. The third lens group G3 is composed of a cemented lens of a biconcave lens and 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 third lens in the third lens group G3 from the object side can be moved as a unit 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, and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and an aperture stop S. The sixth lens group G6 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 seventh lens group is composed of a cemented lens made of a biconvex lens and a biconcave lens, 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 eighth lens group is composed of a cemented lens made of a biconvex lens and a biconcave lens, and a concave meniscus lens with its convex surface facing the image side.

[0095] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0096] 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) 1 343.9661 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 137.2493 9.9850 1.49700 81.61 0.0373 FCD1 3 -1712.2584 0.3000 4 134.6653 8.6790 1.43700 95.10 0.0564 FCD100 5 1410.4900 (d5) 6* 187.9907 3.7612 1.68893 31.16 0.0114 MC-FD80 7 -3501.2938 2.2428 8 412.2384 4.1627 1.80518 25.46 0.0131 FD60-W 9 -181.8095 1.7000 1.86966 20.02 0.0310 FDS20-W 10 931.2470 (d10) 11 -237.4484 1.0000 1.90366 31.31 0.0027 TAFD25 12 64.2329 3.0890 1.86966 20.02 0.0310 FDS20-W 13 204.2995 2.5484 14 -1174.3429 1.0000 1.76385 48.49 -0.0022 S-LAH96 15 78.6333 3.2992 16 -56.8802 1.0000 1.75500 52.32 -0.0069 TAC6 17 91.8683 3.2624 1.85451 25.15 0.0071 NBFD25 18 -439.5060 (d18) 19 165.7709 3.5035 1.78590 43.93 -0.0082 NBFD11 20 -121.0663 0.3000 21 46.7514 6.0992 1.43700 95.10 0.0564 FCD100 22 -55.1688 1.0000 1.91082 35.25 -0.0028 TAFD35 23 566.9565 (d23) 24 81.1462 4.1415 1.78472 25.72 0.0137 FD110 25 -104.1647 0.3000 26 903.9552 1.0000 1.90366 31.31 0.0027 TAFD25 27 30.1527 5.0522 1.43700 95.10 0.0564 FCD100 28 -610.4753 2.8659 29(Aperture) ∞ (d29) 30 64.8093 4.0804 1.74077 27.76 0.0093 E-FD13 31 -64.4844 0.9500 1.94595 17.98 0.0385 FDS18-W 32 -246.9197 (d32) 33 521.8533 3.4017 1.72825 28.32 0.0084 E-FD10 34 -51.8970 1.0000 1.90525 35.04 -0.0005 S-LAH93 35 49.9051 6.9974 36 -317.8132 5.2818 1.61340 44.27 -0.0054 S-NBM51 37 -23.7969 1.0000 1.43700 95.10 0.0564 FCD100 38 -159.4180 (d38) 39 50.0793 8.1181 1.61340 44.27 -0.0054 S-NBM51 40 -29.5410 1.0000 1.55032 75.50 0.0274 FCD705 41 87.0961 5.9221 42 -46.1522 1.0000 1.95375 32.32 -0.0002 TAFD45 43 -248.8162 38.0000 44 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 45∞(BF) Image plane ∞ [Aspheric data] 6 sides K 0.00000 A4 -1.09824E-08 A6 -5.65666E-12 A8 0.00000E+00 A10 0.00000E+00 [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.80 8.64 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 332.70 380.00 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 16.2553 75.5702 138.6392 (d10) 25.9420 19.3242 3.5581 (d18) 33.8449 21.0614 2.0000 (d23) 12.2586 4.8450 2.0000 (d29) 15.9873 28.3904 45.6636 (d32) 14.8156 10.9674 3.3000 (d38) 7.3529 18.9950 31.2956 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 241.5517 G2 6 220.5009 G3 11 -32.8147 G4 19 89.0604 G5 24 264.2149 G6 30 83.0136 G7 33 -100.2002 G8 39 -156.1441 EXAMPLES

[0097] FIG. 8 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.

[0098] The variable magnification imaging optical system in Figure 8 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0099] Starting from the object side, the first lens group G1 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 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 biconcave lens and 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 third lens in the third lens group G3 from the object side can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens G5 is composed of a biconvex lens, a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and an aperture stop S. The sixth lens group G6 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 seventh lens group G7 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 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 eighth lens group G8 is composed of a cemented lens made of a biconvex lens and a convex meniscus lens with its convex surface facing the image side, and a concave meniscus aspheric lens with its convex surface facing the image side.

[0100] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0101] 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) 1 270.2506 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 123.3869 9.9811 1.49700 81.61 0.0373 FCD1 3 3082.3090 0.3000 4 138.0760 9.0305 1.43700 95.10 0.0564 FCD100 5 5793.6278 (d5) 6 168.5968 6.5454 1.71736 29.50 0.0082 E-FD1 7 -115.1765 1.7000 1.92286 20.88 0.0281 E-FDS1-W 8 -372.3141 (d8) 9 -211.1173 1.0000 1.91082 35.25 -0.0028 TAFD35 10 62.5559 3.3013 1.80809 22.76 0.0212 FD225 11 321.8831 2.4251 12 -721.3548 1.0000 1.89190 37.13 -0.0035 S-LAH92 13 84.1266 3.4088 14 -50.5413 1.0000 1.75500 52.32 -0.0069 TAC6 15 92.8170 3.6257 1.85451 25.15 0.0071 NBFD25 16 -171.0854 (d16) 17 180.3625 3.5350 1.76385 48.49 -0.0022 S-LAH96 18 -115.3031 0.3000 19 43.7464 6.3734 1.43700 95.10 0.0564 FCD100 20 -56.1399 1.0000 1.88300 40.80 -0.0094 TAFD30 21 373.6682 (d21) 22 84.7633 4.1207 1.76182 26.61 0.0117 FD140 23 -101.6362 0.3000 24 820.4086 1.0000 1.90366 31.31 0.0027 TAFD25 25 30.5489 4.9442 1.43700 95.10 0.0564 FCD100 26 -1312.8829 2.9375 27(Aperture) ∞ (d27) 28 67.5664 4.1531 1.82115 24.06 0.0186 M-FDS910 29 -57.09521 0.9500 1.98613 16.48 0.0468 FDS16-W 30 -383.7668 (d30) 31 -299.0296 7.1115 1.76182 26.61 0.0117 FD140 32 -60.4236 1.0000 1.90525 35.04 -0.0005 S-LAH93 33 57.0547 5.2631 34 -105.2511 5.5757 1.61340 44.27 -0.0054 S-NBM51 35 -19.5921 1.0000 1.55032 75.50 0.0274 FCD705 36 -51.1477 (d36) 37 83.0515 7.8068 1.61340 44.27 -0.0054 S-NBM51 38 -26.3651 1.0000 1.55032 75.50 0.0274 FCD705 39 -226.0952 8.0994 40* -32.3884 1.0000 1.85135 40.10 -0.0067 MC-TAFD305 41 -160.8643 38.0000 42 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 43∞(BF) Image plane ∞ [Aspheric data] 40 pages K 0.00000 A4 4.11476E-06 A6 2.39346E-09 A8 -3.78970E-12 A10 0.00000E+00 [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.94 8.71 4.22 Image height Y 21.63 21.63 21.63 Lens total length 280.00 330.86 379.94 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 15.4828 72.3067 140.0166 (d8) 27.7714 21.8086 3.1782 (d16) 37.4082 22.8125 2.0000 (d21) 8.8177 3.2052 3.2110 (d27) 15.4792 29.4878 45.3977 (d30) 13.3398 10.0111 3.9730 (d36) 6.4128 15.9410 26.8760 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 236.8984 G2 6 202.7312 G3 9 -33.1563 G4 17 87.3253 G5 22 335.9740 G6 28 84.5267 G7 31 -96.4938 G8 37 -166.3194 EXAMPLES

[0102] FIG. 15 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.

[0103] The variable magnification image-forming optical system in Figure 15 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0104] From the object side, the first lens group G1 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 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 with a convex surface facing the image side. The third lens group G3 is composed of a cemented lens of a biconcave lens and 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 third lens in the third lens group G3 from the object side can be moved as a whole in a direction perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 is composed of a biconvex lens and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens G5 is composed of a biconvex lens, a cemented lens of a biconcave lens and a biconvex lens, and an aperture stop S. 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 biconvex lens and a biconcave lens, and a cemented lens 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 eighth lens group G8 is composed of a cemented lens of a biconvex lens and a biconcave lens, and a concave meniscus aspheric lens with its convex surface facing the image side.

[0105] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0106] 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) 1 319.6686 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 134.3655 10.1334 1.49700 81.61 0.0373 FCD1 3 -1789.9685 0.3000 4 130.8633 8.7672 1.43700 95.10 0.0564 FCD100 5 1193.3560 (d5) 6 163.8229 6.5170 1.72825 28.32 0.0084 E-FD10 7 -117.7637 1.7000 1.92286 20.88 0.0281 E-FDS1-W 8 -428.5711 (d8) 9 -234.1517 1.0000 1.91082 35.25 -0.0028 TAFD35 10 64.5933 3.1869 1.80809 22.76 0.0212 FD225 11 267.3976 2.4704 12 -748.0078 1.0000 1.89190 37.13 -0.0035 S-LAH92 13 77.5542 3.4277 14 -53.6852 1.0000 1.75500 52.32 -0.0069 TAC6 15 94.1904 3.5312 1.85451 25.15 0.0071 NBFD25 16 -181.2814 (d16) 17 223.4266 3.4945 1.76385 48.49 -0.0022 S-LAH96 18 -101.8072 0.3000 19 44.8782 6.1793 1.43700 95.10 0.0564 FCD100 20 -53.8080 1.0000 1.88300 40.80 -0.0094 TAFD30 21 332.7872 (d21) 22 90.3432 4.1161 1.76182 26.61 0.0117 FD140 23 -91.1154 0.3000 24 -2826.2092 1.0000 1.90366 31.31 0.0027 TAFD25 25 32.1548 4.9609 1.43700 95.10 0.0564 FCD100 26 -327.1621 2.7504 27(Aperture) ∞ (d27) 28 68.7489 3.9772 1.78880 28.43 0.0036 S-NBH58 29 -68.4474 0.9500 1.94595 17.98 0.0385 FDS18-W 30 -315.4532 (d30) 31 286.5407 3.5371 1.75520 27.53 0.0102 E-FD4 32 -56.9745 1.1904 1.90525 35.04 -0.0005 S-LAH93 33 50.7830 8.1559 34 -97.2935 4.6269 1.61340 44.27 -0.0054 S-NBM51 35 -24.7315 1.0000 1.43700 95.10 0.0564 FCD100 36 -81.2636 (d36) 37 58.8439 8.1405 1.61340 44.27 -0.0054 S-NBM51 38 -27.3056 1.0000 1.55032 75.50 0.0274 FCD705 39 285.6960 4.8658 40* -40.1382 1.0000 1.85135 40.10 -0.0067 M-TAFD305 41 -603.0123 38.0000 42 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 43∞(BF) Image plane ∞ [Aspheric data] 40 pages K 0.00000 A4 1.28400E-06 A6 1.53819E-09 A8 -4.21710E-12 A10 0.00000E+00 [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.50 Full angle of view 2ω 15.82 8.65 4.18 Image height Y 21.63 21.63 21.63 All lenses 280.00 330.49 377.79 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 17.3595 74.2697 139.1100 (d8) 27.1308 20.7107 3.1668 (d16) 34.6682 21.4987 2.0000 (d21) 12.8071 4.8278 2.0000 (d27) 16.3790 29.6787 47.3433 (d30) 16.5105 11.6500 3.3000 (d36) 5.0663 17.7759 30.7878 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 233.6004 G2 6 202.7419 G3 9 -32.8004 G4 17 93.7925 G5 22 280.3042 G6 28 82.3382 G7 31 -103.1781 G8 37 -148.2351 EXAMPLES

[0107] FIG. 22 is a lens configuration diagram of a variable magnification image forming optical system according to Example 4 when focused on an object at infinity at the wide-angle end.

[0108] 22 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 middle group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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. Of these, the third lens group G3 and the eighth lens group G8 are fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.

[0109] From the object side, the first lens group G1 is composed of a biconvex lens, 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 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 cemented lens of a biconcave lens and 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 third lens in the third lens group G3 from the object side can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and an aperture stop S. The sixth lens group G6 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 seventh lens group G7 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 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 concave meniscus lens with its convex surface facing the image side, and a concave meniscus lens with its convex surface facing the image side.

[0110] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0111] The values ​​of the specifications of the 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) 1 243.1639 6.3150 1.54072 47.20 0.0043 E-FEL2 2 -15831.3271 0.3000 3 831.9466 1.0000 1.61340 44.27 -0.0054 S-NBM51 4 116.5780 9.6560 1.49700 81.61 0.0373 FCD1 5 977.2246 0.3000 6 136.0279 8.1708 1.43700 95.10 0.0564 FCD100 7 974.6286 (d7) 8 144.1143 6.4392 1.71736 29.50 0.0082 E-FD1 9 -136.5050 1.7000 1.92286 20.88 0.0281 E-FDS1-W 10 -602.7382 (d10) 11 -271.3649 1.0000 1.90366 31.31 0.0027 TAFD25 12 44.2291 3.8321 1.80809 22.76 0.0212 FD225 13 199.3949 2.6430 14 -541.2048 1.0000 1.91082 35.25 -0.0028 TAFD35 15 75.3305 3.4267 16 -54.0192 1.0000 1.75500 52.32 -0.0069 TAC6 17 100.4512 3.5770 1.85451 25.15 0.0071 NBFD25 18 -152.8942 (d18) 19 183.0470 3.5418 1.80400 46.53 -0.0070 S-LAH65VS 20 -121.8557 0.3000 21 45.2062 6.4247 1.43700 95.10 0.0564 FCD100 22 -55.5403 1.0000 1.88300 40.80 -0.0094 TAFD30 23 618.1086 (d23) 24 81.1220 5.0872 1.76182 26.61 0.0117 FD140 25 -101.9330 0.3000 26 1369.4296 1.0000 1.90366 31.31 0.0027 TAFD25 27 30.0996 4.9843 1.43700 95.10 0.0564 FCD100 28 -1177.0706 3.0000 29(Aperture) ∞ (d29) 30 63.1326 4.7482 1.72825 28.32 0.0084 E-FD10 31 -59.0534 0.9001 1.94595 17.98 0.0385 FDS18-W 32 -207.6000 (d32) 33 -1244.5251 3.0434 1.85451 25.15 0.0071 NBFD25 34 -65.4568 1.0000 1.90525 35.04 -0.0005 S-LAH93 35 44.5101 5.7246 36 75.3805 6.2532 1.61340 44.27 -0.0054 S-NBM51 37 -28.1481 1.1000 1.43700 95.10 0.0564 FCD100 38 -611.7864 (d38) 39 -45.9879 3.9073 1.61340 44.27 -0.0054 S-NBM51 40 -24.5931 1.0000 1.59282 68.62 0.0192 FCD515 41 -91.9125 11.9722 42 -56.4352 1.0000 1.65100 56.24 -0.0051 S-LAL54Q 43 -136.0129 34.1752 44 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 45∞(BF) Image plane ∞ [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.77 8.63 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 329.76 380.00 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d7) 14.3883 69.8000 138.5981 (d10) 27.3938 21.7418 3.1841 (d18) 36.0165 20.7312 2.0000 (d23) 12.9782 7.2917 2.4829 (d29) 12.2363 28.8202 49.4095 (d32) 15.4578 11.9759 3.3000 (d38) 7.2073 15.0770 26.7037 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 237.4400 G2 8 200.0732 G3 11 -31.4940 G4 19 83.2267 G5 24 358.6032 G6 30 80.8993 G7 33 -224.3909 G8 39 -75.7695 EXAMPLES

[0112] FIG. 29 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.

[0113] The variable magnification imaging optical system in Figure 29 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0114] Starting from the object side, the first lens group G1 is composed of a convex meniscus lens with a convex surface facing the object side, 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 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 biconcave lens and a cemented lens of 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 third lens in the third lens group G3 from the object side can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and an aperture stop S. The sixth lens group G6 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 seventh lens group G7 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 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 concave meniscus lens with its convex surface facing the image side, and a concave meniscus lens with its convex surface facing the image side.

[0115] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0116] 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) 1 233.5565 6.2800 1.54072 47.20 0.0043 E-FEL2 2 10339.3928 0.3000 3 609.6076 1.0000 1.61340 44.27 -0.0054 S-NBM51 4 111.0560 9.5444 1.49700 81.61 0.0373 FCD1 5 645.8147 0.3000 6 136.5214 8.2989 1.43700 95.10 0.0564 FCD100 7 1106.9453 (d7) 8 144.5067 6.4741 1.71736 29.50 0.0082 E-FD1 9 -134.0101 1.7000 1.92286 20.88 0.0281 E-FDS1-W 10 -567.3931 (d10) 11 -284.0253 1.0017 1.90366 31.31 0.0027 TAFD25 12 43.7115 3.8593 1.80809 22.76 0.0212 FD225 13 204.5252 2.6415 14 -491.4971 1.0000 1.91082 35.25 -0.0028 TAFD35 15 75.2496 3.4414 16 -53.1195 1.0000 1.75500 52.32 -0.0069 TAC6 17 101.4228 3.5963 1.85451 25.15 0.0071 NBFD25 18 -144.3749 (d18) 19 171.4282 3.5196 1.80400 46.53 -0.0070 S-LAH65VS 20 -127.1274 0.3000 21 44.8668 6.3948 1.43700 95.10 0.0564 FCD100 22 -55.8114 1.0000 1.88300 40.80 -0.0094 TAFD30 23 627.3771 (d23) 24 82.9230 4.1524 1.76182 26.61 0.0117 FD140 25 -99.5863 0.3000 26 11254.7008 1.0000 1.90366 31.31 0.0027 TAFD25 27 29.9857 5.0217 1.43700 95.10 0.0564 FCD100 28 -820.3525 3.0000 29(Aperture) ∞ (d29) 30 64.3627 6.6908 1.72825 28.32 0.0084 E-FD10 31 -58.3812 0.9001 1.94595 17.98 0.0385 FDS18-W 32 -191.4464 (d32) 33 -267.1342 4.1367 1.85451 25.15 0.0071 NBFD25 34 -56.8303 1.2143 1.90525 35.04 -0.0005 S-LAH93 35 49.0306 2.7931 36 108.5422 6.1149 1.61340 44.27 -0.0054 S-NBM51 37 -25.0637 1.1000 1.43700 95.10 0.0564 FCD100 38 -152.2184 (d38) 39 -43.5479 4.5674 1.61340 44.27 -0.0054 S-NBM51 40 -21.1607 1.0000 1.59282 68.62 0.0192 FCD515 41 -73.8245 12.0314 42* -34.0872 1.0000 1.58913 61.25 -0.0008 M-BACD5N 43 -58.9937 33.3544 44 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 45∞(BF) Image plane ∞ [Aspheric data] 42 sides K 0.00000 A4 1.77321E-06 A6 4.84830E-10 A8 1.81647E-12 A10 0.00000E+00 [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.81 8.65 4.19 Image height Y 21.63 21.63 21.63 Lens total length 280.00 329.48 380.00 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d7) 14.0656 68.9309 137.9505 (d10) 27.0980 21.7154 3.2131 (d18) 36.2114 20.8134 2.0000 (d23) 12.4766 6.6423 2.0000 (d29) 12.8429 29.7621 51.1652 (d32) 14.9642 11.6246 3.3016 (d38) 8.8120 16.4647 26.8403 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 237.1781 G2 8 197.9998 G3 11 -31.6795 G4 19 82.2087 G5 24 444.6270 G6 30 80.2815 G7 33 -185.3355 G8 39 -79.5823 EXAMPLES

[0117] FIG. 36 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.

[0118] The variable magnification imaging optical system in Figure 36 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0119] From the object side, the first lens group G1 is composed of a biconvex lens, 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 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 cemented lens of a biconcave lens and 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 third lens in the third lens group G3 from the object side can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, 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 an aperture stop S. 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, and 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, and a cemented lens 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 eighth lens group G8 is composed 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.

[0120] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0121] 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) 1 187.2499 10.5731 1.51742 52.15 0.0044 E-CF6 2 -6980.7851 0.5001 3 587.5167 2.5000 1.61340 44.27 -0.0054 S-NBM51 4 114.1289 13.9789 1.43700 95.10 0.0564 FCD100 5 1670.4940 0.5000 6 142.8729 7.9442 1.43700 95.10 0.0564 FCD100 7 349.1077 (d7) 8 230.8807 7.3383 1.85451 25.15 0.0071 NBFD25 9 -125.3374 1.7000 1.92286 20.88 0.0281 E-FDS1-W 10 -2754.6838 (d10) 11 -236.4346 1.0001 1.91082 35.25 -0.0028 TAFD35 12 63.1574 3.4085 1.80809 22.76 0.0212 FD225 13 322.6977 2.5741 14 -340.3017 1.0000 1.89190 37.13 -0.0035 S-LAH92 15 80.7875 3.5943 16 -58.9808 1.0000 1.75500 52.32 -0.0069 TAC6 17 88.0129 3.6236 1.85451 25.15 0.0071 NBFD25 18 -197.5814 (d18) 19 263.7071 3.2084 1.90525 35.04 -0.0005 S-LAH93 20 -143.6140 0.3000 21 47.1486 6.3388 1.43700 95.10 0.0564 FCD100 22 -55.9032 1.0000 1.91082 35.25 -0.0028 TAFD35 23 4229.2812 (d23) 24 92.8855 8.2070 1.78472 25.72 0.0137 FD110 25 -96.8966 0.3000 26 1289.9614 1.0000 1.85883 30.00 0.0035 NBFD30 27 29.4900 4.9864 1.43700 95.10 0.0564 FCD100 28 6158.7194 3.0132 29(Aperture) ∞ (d29) 30 78.4965 4.8339 1.48749 70.44 0.0090 FC5 31 -42.3078 0.9500 1.85150 40.78 -0.0055 S-LAH89 32 -950.1849 3.9620 33 157.3584 3.9404 1.85451 25.15 0.0071 NBFD25 34 -41.8276 0.8999 1.94595 17.98 0.0385 FDS18-W 35 -82.1017 (d35) 36 -148.5129 3.0509 1.85451 25.15 0.0071 NBFD25 37 -50.6274 1.0000 1.90525 35.04 -0.0005 S-LAH93 38 58.7987 3.3985 39 -1890.0496 5.9301 1.61340 44.27 -0.0054 S-NBM51 40 -23.8037 1.1000 1.43700 95.10 0.0564 FCD100 41 -146.9669 (d41) 42 48.5569 12.0000 1.61340 44.27 -0.0054 S-NBM51 43 -27.5588 1.3000 1.59282 68.62 0.0192 FCD515 44 59.3890 8.9693 45 -41.3382 1.8026 1.95375 32.32 -0.0002 TAFD45 46 -93.5305 35.9298 47 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 48∞(BF) Image plane ∞ [Various data] Zoom ratio 4.44 Wide Angle Mid-Telephoto Focal length 153.00 330.00 679.00 F-number 5.17 5.80 6.49 Full angle of view 2ω 15.79 7.33 3.56 Image height Y 21.63 21.63 21.63 Lens length 310.82 380.37 424.11 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d7) 9.2538 90.9763 156.8686 (d10) 38.0425 25.8709 3.7170 (d18) 34.4217 19.0175 2.0000 (d23) 12.9790 5.8139 2.0000 (d29) 15.4267 30.9587 49.2023 (d35) 16.5394 12.9515 3.3000 (d41) 2.0000 12.6253 24.8647 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 259.3687 G2 8 286.2981 G3 11 -33.3382 G4 19 90.9296 G5 24 307.3754 G6 30 76.1462 G7 36 -95.1657 G8 42 -153.7918 EXAMPLES

[0122] FIG. 43 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.

[0123] The variable magnification imaging optical system in Figure 43 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, an intermediate group GM consisting of a fourth lens group G4, a fifth lens group G5 and a sixth lens group G6, a focusing group GF consisting of a seventh lens group G7 that focuses 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.

[0124] Starting from the object side, the first lens group G1 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 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 biconcave lens and a convex meniscus lens with a convex surface facing the object side, a concave meniscus lens with a convex surface facing the object side, and a cemented lens of a biconcave lens and a biconvex lens. In addition, the third lens in the third lens group G3 from the object side can be moved as a unit in a direction perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a cemented lens of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. 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. The sixth lens group G6 consists of a cemented lens made of a biconcave lens and a biconvex lens, and an aperture stop S. The seventh lens group G7 consists 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 consists 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 consists of a cemented lens made of a biconvex lens and a biconcave lens, and a concave meniscus lens with its convex surface facing the image side.

[0125] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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. 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 decreases, the distance between the sixth lens group 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 an object at a close distance, the focusing group GF moves along the optical axis toward the object.

[0126] 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) 1 389.7091 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 139.1338 10.5967 1.49700 81.61 0.0373 FCD1 3 -814.2988 0.3000 4 121.9323 9.0817 1.43700 95.10 0.0564 FCD100 5 863.7195 (d5) 6 196.9932 6.6580 1.68893 31.16 0.0066 E-FD8 7 -110.7640 1.7000 1.92286 20.88 0.0281 E-FDS1-W 8 -292.8899 (d8) 9 -278.5726 1.0000 1.91082 35.25 -0.0028 TAFD35 10 70.3755 3.1627 1.86966 20.02 0.0310 FDS20-W 11 269.3865 2.3593 12 3896.4868 1.0000 1.89190 37.13 -0.0035 S-LAH92 13 66.2813 3.9722 14 -42.8388 1.0000 1.75500 52.32 -0.0069 TAC6 15 89.9067 3.8842 1.85451 25.15 0.0071 NBFD25 16 -131.6183 (d16) 17 183.5860 3.4713 1.77250 49.62 -0.0088 TAF1 18 -146.2853 0.3000 19 54.3354 6.5173 1.43700 95.10 0.0564 FCD100 20 -48.8701 1.0000 1.91082 35.25 -0.0028 TAFD35 21 -529.4148 (d21) 22 98.9291 1.0000 1.91082 35.25 -0.0028 TAFD35 23 50.7153 5.5606 1.78472 25.72 0.0137 FD110 24 -78.4210 (d24) 25 -112.0223 1.0000 1.85451 25.15 0.0071 NBFD25 26 39.1137 5.1447 1.43700 95.10 0.0564 FCD100 27 -85.6726 2.0398 28(Aperture) ∞ (d28) 29 69.3037 4.5713 1.82115 24.06 0.0186 M-FDS910 30 -43.6762 0.9500 1.94595 17.98 0.0385 FDS18-W 31 -285.6609 (d31) 32 -1825.1370 3.5622 1.72825 28.32 0.0101 E-FD10L 33 -42.5162 1.0000 1.90525 35.04 -0.0005 S-LAH93 34 57.5198 3.1686 35 257.4318 5.4256 1.61340 44.27 -0.0054 S-NBM51 36 -24.6427 1.0000 1.43700 95.10 0.0564 FCD100 37 411.6347 (d37) 38 54.4332 7.7620 1.61340 44.27 -0.0054 S-NBM51 39 -25.3337 1.0000 1.59282 68.62 0.0192 FCD515 40 115.0529 10.8351 41 -45.6456 5.4592 1.95375 32.32 -0.0002 TAFD45 42 -179.2772 38.0000 43 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 44∞(BF) Image plane ∞ [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.78 8.64 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 324.85 378.28 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 9.5384 57.7988 133.3604 (d8) 28.6956 25.2860 3.1500 (d16) 30.6964 16.2087 2.0000 (d21) 13.6571 8.5229 2.0000 (d24) 5.5000 5.3147 4.4606 (d28) 16.2169 29.7774 46.3590 (d31) 13.7130 12.6024 3.3000 (d37) 2.0000 9.3573 23.6638 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 226.6295 G2 6 221.3431 G3 9 -32.1034 G4 17 98.6827 G5 22 60.6770 G6 25 -77.5843 G7 29 81.4704 G8 32 -91.3838 G9 38 -165.7131 EXAMPLES

[0127] FIG. 50 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.

[0128] The variable magnification imaging optical system in Figure 50 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0129] Starting from the object side, the first lens group G1 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 convex meniscus lens with a convex surface facing the object side. The second lens group G2 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 convex meniscus lens with a convex surface facing the object side. The third lens group G3 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 biconcave 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 lens in the third lens group G3 and subsequent lenses from the object side can be moved as a unit in a direction perpendicular to the optical axis to function as an image stabilizing group. The fourth lens group G4 is composed of a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, a biconvex lens, and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of an aperture stop S, a cemented lens consisting of a biconvex lens and a biconcave lens, and a convex meniscus aspheric lens with its convex surface facing the image side. The sixth lens group G6 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with its convex surface facing the image side. The seventh lens group G7 consists of a biconcave lens, and a cemented lens consisting of a biconvex lens and a biconcave lens. The eighth lens group G8 consists of a convex meniscus lens with its convex surface facing the image side, a cemented lens consisting of a concave meniscus lens with its convex surface facing the image side, and a convex meniscus lens with its convex surface facing the object side.

[0130] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0131] 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) 1 579.9071 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 152.2143 10.4479 1.49700 81.61 0.0373 FCD1 3 -604.1888 0.3000 4 131.3007 9.0104 1.43700 95.10 0.0564 FCD100 5 922.1037 (d5) 6 44.1697 6.0458 1.59270 35.45 0.0080 FF5 7 78.9523 1.0000 1.94595 17.98 0.0385 FDS18-W 8 48.0363 5.7042 9 103.5342 4.0133 1.85451 25.15 0.0071 NBFD25 10 471.1775 (d10) 11 189.1824 1.0000 1.91082 35.25 -0.0028 TAFD35 12 42.0985 2.7792 13 56.1332 3.3637 1.80809 22.76 0.0212 FD225 14 182.3238 2.9999 15 -216.4711 1.0000 1.76385 48.49 -0.0022 S-LAH96 16 160.5965 3.1479 17 -60.5486 1.0000 1.75500 52.32 -0.0069 TAC6 18 52.1131 3.5247 1.85451 25.15 0.0071 NBFD25 19 337.0663 (d19) 20 113.6608 1.0000 1.91082 35.25 -0.0028 TAFD35 21 36.0530 5.4378 1.43700 95.10 0.0564 FCD100 22 -191.8626 0.3000 23 38.6367 5.9100 1.75520 27.53 0.0102 E-FD4 24 -143.0515 0.3222 25 51.6077 5.2824 1.43700 95.10 0.0564 FCD100 26 -76.1108 1.0000 1.91082 35.25 -0.0028 TAFD35 27 76.7228 (d27) 28(Aperture) ∞ 9.1904 29 63.4636 4.2829 1.43700 95.10 0.0564 FCD100 30 -63.5440 1.2001 1.90043 37.37 -0.0045 TAFD37A 31 63.0932 3.4787 32* -203.2419 3.5033 1.58313 59.46 -0.0009 M-BACD12 33 -41.4656 (d33) 34 50.7927 5.1726 1.64769 33.84 0.0049 E-FD2 35 -46.9644 1.3414 1.92286 20.88 0.0281 E-FDS1-W 36 -140.9238 (d36) 37 -178.8291 1.0000 1.80400 46.53 -0.0070 S-LAH65VS 38 35.8680 2.0569 39 38.8724 6.6228 1.61340 44.27 -0.0054 S-NBM51 40 -30.1232 1.0000 1.43700 95.10 0.0564 FCD100 41 72.7151 (d41) 42 -30.0787 3.4493 1.61340 44.27 -0.0054 S-NBM51 43 -23.4456 1.0000 1.55032 75.50 0.0274 FCD705 44 -179.6018 0.3000 45 85.6352 2.9626 1.65412 39.62 -0.0034 E-ADF50 46 249.2094 30.9434 47 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 48∞(BF) Image plane ∞ [Aspheric data] 32 sides K 0.00000 A4 -4.33342E-08 A6 -2.55803E-09 A8 1.11052E-11 A10 -5.60665E-14 [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.02 5.49 6.47 Full angle of view 2ω 15.98 8.65 4.18 Image height Y 21.63 21.63 21.63 Lens length 277.57 322.64 374.90 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 25.2041 67.0835 133.3063 (d10) 14.2722 17.4642 3.5000 (d19) 32.4108 22.1380 2.0000 (d27) 9.7626 7.4869 4.0959 (d33) 5.9953 15.6263 33.5618 (d36) 25.5122 14.8666 3.3000 (d41) 5.8202 19.3832 36.5434 (BF) 0.9998 0.9998 0.9998 [Lens group data] Group starting plane focal length G1 1 251.9611 G2 6 189.8904 G3 11 -33.2780 G4 20 65.9690 G5 28 -458.0840 G6 34 74.7329 G7 37 -95.6183 G8 42 -110.2315 EXAMPLES

[0132] FIG. 57 is a lens configuration 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.

[0133] The variable magnification imaging optical system in Figure 57 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0134] Starting from the object side, the first lens group G1 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 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 biconcave lens and a convex meniscus lens with a convex surface facing the object side, a concave meniscus lens with a convex surface facing the object side, and a cemented lens of a biconcave lens and a biconvex lens. In addition, the third lens in the third lens group G3 from the object side can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, 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 an aperture stop S. The sixth lens group G6 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 seventh lens group G7 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 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 eighth lens group G8 is composed of a cemented lens made of a biconvex lens and a biconcave lens, and a biconcave lens.

[0135] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0136] 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) 1 306.1368 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 119.4311 11.1758 1.49700 81.61 0.0373 FCD1 3 -1564.9947 0.3000 4 115.8086 9.7306 1.43700 95.10 0.0564 FCD100 5 1272.7922 (d5) 6 198.2576 5.9401 1.74077 27.76 0.0093 E-FD13 7 -112.5000 1.7500 1.92286 20.88 0.0281 E-FDS1-W 8 -365.7622 (d8) 9 -168.2166 1.0000 1.91082 35.25 -0.0028 TAFD35 10 59.2631 3.416 1.80809 22.76 0.0212 FD225 11 345.1624 2.2129 12 1274.0357 1.0000 1.90525 35.04 -0.0005 S-LAH93 13 73.0217 3.4826 14 -47.5794 1.0000 1.75500 52.32 -0.0069 TAC6 15 85.2666 3.6871 1.85451 25.15 0.0071 NBFD25 16 -183.2175 (d16) 17 166.2244 3.2909 1.95375 32.32 -0.0002 TAFD45 18 -172.3070 0.3000 19 45.8965 6.3246 1.43700 95.10 0.0564 FCD100 20 -53.6547 1.0000 1.91082 35.25 -0.0028 TAFD35 21 691.1398 (d21) 22 100.8863 5.1641 1.74077 27.76 0.0093 E-FD13 23 -95.3962 0.3000 24 145.4275 1.0000 1.95150 29.83 0.0008 M-TAFD405 25 29.5130 4.8470 1.43700 95.10 0.0564 FCD100 26 521.3381 3.1572 27(Aperture) ∞ (d27) 28 60.1164 3.9968 1.72825 28.32 0.0101 E-FD10L 29 -69.5593 0.7502 1.94595 17.98 0.0385 FDS18-W 30 -345.0749 (d30) 31 -242.0894 4.8245 1.74077 27.76 0.0093 E-FD13 32 -39.8479 0.9001 1.90525 35.04 -0.0005 S-LAH93 33 56.4880 8.7681 34 -270.7667 6.0094 1.61340 44.27 -0.0054 S-NBM51 35 -23.0230 1.0000 1.43700 95.10 0.0564 FCD100 36 -80.0688 (d36) 37 52.6315 7.7249 1.61340 44.27 -0.0054 S-NBM51 38 -36.8914 1.0000 1.55032 75.50 0.0274 FCD705 39 104.3172 10.4427 40 -56.5120 1.0000 1.95375 32.32 -0.0002 TAFD45 41 2499.3743 36.2377 42 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 43∞(BF) Image plane ∞ [Various data] Zoom ratio 4.66 Wide Angle Mid-Telephoto Focal length 124.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 19.55 8.64 4.18 Image height Y 21.63 21.63 21.63 Lens length 269.94 332.78 369.94 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 2.0000 70.4852 122.8199 (d8) 24.1171 18.4694 3.2972 (d16) 38.6149 22.9105 2.0000 (d21) 11.0957 4.3032 3.3603 (d27) 17.0604 32.1291 45.7537 (d30) 15.8170 10.4066 3.3733 (d36) 2.0000 14.8386 30.1006 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 210.6175 G2 6 216.2398 G3 9 -30.8188 G4 17 86.7315 G5 22 268.0520 G6 28 85.2738 G7 31 -112.5689 G8 37 -158.3739 EXAMPLES

[0137] FIG. 64 is a lens arrangement 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.

[0138] The variable magnification imaging optical system in Figure 64 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, an intermediate group GM consisting of a fourth lens group, a focusing group GF consisting of a fifth lens group G5 that focuses from an object at infinity to a close object, and a subsequent group GR consisting of a sixth lens group G6 and a seventh lens group G7.

[0139] From the object side, the first lens group G1 is composed of a biconvex lens, a cemented lens 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 biconvex lens. The second lens group G2 is composed of a biconvex lens, and 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 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 third lens in the third lens group G3 from the object side can be moved as a whole 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 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 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 biconcave lens, and a cemented lens of a biconvex lens and a biconcave lens. The seventh lens group G7 is composed 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.

[0140] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 and the seventh lens group G7 are 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 fourth lens group G4 to the sixth lens group G6 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 decreases, and the distance between the sixth lens group and the seventh lens group G7 increases, and when focusing from an object at infinity to an object at a close distance, the focusing group GF moves toward the object side along the optical axis.

[0141] 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) 1 295.0061 3.0000 1.74330 49.22 -0.0104 NBF1 2 110.3302 10.5086 1.49700 81.61 0.0373 FCD1 3 1870.9247 0.4000 4 124.5682 10.3748 1.43700 95.10 0.0564 FCD100 5 -2054.1224 (d5) 6 104.8720 5.1223 1.85451 25.15 0.0071 NBFD25 7 -1044.1668 1.7068 8 61.1820 7.8724 1.74077 27.76 0.0093 E-FD13 9 -115.9419 1.0000 1.92286 20.88 0.0281 E-FDS1-W 10 54.2668 (d10) 11 -888.9111 1.0000 1.90525 35.04 -0.0005 S-LAH93 12 42.3623 3.5953 1.86966 20.02 0.0310 FDS20-W 13 105.2786 6.0658 14 -893.2105 1.0000 1.90525 35.04 -0.0005 S-LAH93 15 87.3700 4.9709 16 -47.6247 1.0000 1.75500 52.32 -0.0069 TAC6 17 85.8391 3.7759 1.85451 25.15 0.0071 NBFD25 18 -161.2551 (d18) 19 37.4433 5.9572 1.43700 95.10 0.0564 FCD100 20 -186.9692 0.3000 21 50.7378 6.5269 1.80000 29.84 0.0070 S-NBH55 22 -48.1386 1.0000 1.91082 35.25 -0.0028 TAFD35 23 35.1280 3.4934 24 75.5437 4.9776 1.55032 75.50 0.0274 FCD705 25 -57.9590 0.3000 26 49.5121 5.6674 1.43700 95.10 0.0564 FCD100 27 -46.5082 0.8999 1.88300 40.80 -0.0094 TAFD30 28 156.1854 1.9938 29(Aperture) ∞ (d29) 30 79.7700 4.7256 1.78470 26.29 0.0124 S-TIH23 31 -42.3283 0.9000 1.94595 17.98 0.0385 FDS18-W 32 -130.6060 (d32) 33 299.1828 3.1104 1.67270 32.17 0.0058 E-FD5 34 -73.4981 0.8999 1.90525 35.04 -0.0005 S-LAH93 35 41.4937 9.2853 36 113.9460 6.0430 1.61340 44.27 -0.0054 S-NBM51 37 -26.6550 0.9000 1.43700 95.10 0.0564 FCD100 38 114.1041 (d38) 39 76.6609 7.4751 1.61340 44.27 -0.0054 S-NBM51 40 -31.1781 0.9000 1.55032 75.50 0.0274 FCD705 41 188.1059 12.1506 42 -49.2168 0.9000 1.95375 32.32 -0.0002 TAFD45 43 -169.1533 36.9237 44 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 45∞(BF) Image plane ∞ [Various data] Zoom ratio 3.77 Wide Angle Mid-Telephoto Focal length 154.50 300.00 582.00 F-number 5.15 5.78 6.47 Full angle of view 2ω 15.68 8.07 4.15 Image height Y 21.63 21.63 21.63 Lens total length 287.50 355.67 387.50 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 22.8715 99.9027 132.6797 (d10) 15.7326 6.8694 5.9244 (d18) 38.5762 23.5107 3.0000 (d29) 17.3388 18.8162 24.4622 (d32) 10.1232 8.6458 3.0000 (d38) 2.6320 17.6976 38.2081 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 268.4950 G2 6 216.2574 G3 11 -30.4251 G4 19 65.3559 G5 30 75.9862 G6 33 -79.1825 G7 39 -209.0581 EXAMPLES

[0142] FIG. 71 is a lens arrangement 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.

[0143] The variable magnification image forming optical system of Fig. 71 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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. Of these, the third lens group G3 and the eighth lens group G8 are fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.

[0144] Starting from the object side, the first lens group G1 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 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 biconcave lens and 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 third lens in the third lens group G3 from the object side can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and an aperture stop S. The sixth lens group G6 is composed of a cemented lens consisting 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 consisting of a convex meniscus lens with its convex surface facing the image side and a biconcave lens, and a cemented lens consisting 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 consisting of a biconvex lens and a biconcave lens, and a concave meniscus lens with its convex surface facing the image side.

[0145] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0146] 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) 1 293.4289 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 129.4929 10.2107 1.49700 81.61 0.0373 FCD1 3 -2964.9103 0.3000 4 129.1913 8.9310 1.43700 95.10 0.0564 FCD100 5 1343.7408 (d5) 6 176.3295 6.8508 1.72825 28.32 0.0084 E-FD10 7 -135.0849 1.7000 1.92286 20.88 0.0281 E-FDS1-W 8 -550.4855 (d8) 9 -226.8061 1.0000 1.90366 31.31 0.0027 TAFD25 10 65.0394 3.0778 1.86966 20.02 0.0310 FDS20-W 11 211.5722 2.4594 12 -6513.4567 1.0000 1.85150 40.78 -0.0055 S-LAH89 13 75.6520 3.3960 14 -54.3210 1.0000 1.75500 52.32 -0.0069 TAC6 15 93.3537 3.3744 1.85451 25.15 0.0071 NBFD25 16 -260.4553 (d16) 17 166.3029 3.4704 1.76385 48.49 -0.0022 S-LAH96 18 -123.7194 0.3000 19 46.6844 6.1048 1.43700 95.10 0.0564 FCD100 20 -54.0187 1.0000 1.88300 40.80 -0.0094 TAFD30 21 466.0069 (d21) 22 83.9125 4.1429 1.76182 26.61 0.0117 FD140 23 -97.5227 0.3000 24 2201.3945 1.0000 1.90366 31.31 0.0027 TAFD25 25 31.2693 5.0391 1.43700 95.10 0.0564 FCD100 26 -343.1765 2.7612 27(Aperture) ∞ (d27) 28 66.7519 4.1694 1.74077 27.76 0.0093 E-FD13 29 -58.0846 0.9500 1.94595 17.98 0.0385 FDS18-W 30 -207.1156 (d30) 31 -547.7018 5.7886 1.80518 25.46 0.0131 FD60-W 32 -65.8673 1.0000 1.90525 35.04 -0.0005 S-LAH93 33 50.7044 8.7489 34 906.0646 5.4801 1.61340 44.27 -0.0054 S-NBM51 35 -26.0200 1.0000 1.43700 95.10 0.0564 FCD100 36 -399.4927 (d36) 37 55.3857 12.0000 1.61340 44.27 -0.0054 S-NBM51 38 -26.7381 1.0000 1.59282 68.62 0.0192 FCD515 39 109.9799 8.0091 40 -51.1269 1.0000 1.95375 32.32 -0.0002 TAFD45 41 -264.2231 37.7920 42 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 43∞(BF) Image plane ∞ [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.77 8.63 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 330.13 376.10 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 8.6377 67.1374 133.3159 (d8) 32.7521 24.3825 4.1755 (d16) 36.0919 22.4193 2.0000 (d21) 11.4596 4.6884 2.7741 (d27) 15.0021 27.1314 45.7706 (d30) 13.1999 9.5716 3.3000 (d36) 2.0004 13.9431 23.9092 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 227.8174 G2 6 229.4647 G3 9 -32.5649 G4 17 92.5597 G5 22 253.5860 G6 28 82.7289 G7 31 -97.6335 G8 37 -167.3767 EXAMPLES

[0147] FIG. 78 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.

[0148] The variable magnification imaging optical system in Figure 78 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0149] Starting from the object side, the first lens group G1 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 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 biconcave lens and 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 third and subsequent lenses from the object side in the third lens group G3 can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, 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 an aperture stop S. 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, and a cemented lens 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 of a biconvex lens and a biconcave lens, and a biconcave lens.

[0150] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0151] 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 ΔPgF Applicable glass material 0 (d0) 1 272.0457 3.0000 1.61310 44.36 -0.0081 E-ADF10 2 125.1732 10.2405 1.49700 81.61 0.0373 FCD1 3 -13553.5354 0.3000 4 130.0457 8.9911 1.43700 95.10 0.0564 FCD100 5 1630.9345 (d5) 6 206.9202 6.6711 1.84666 23.78 0.0149 S-TIH53W 7 -163.6109 1.7000 2.10420 17.02 0.0452 E-FDS3 8 -771.1508 (d8) 9 -225.6368 1.0000 1.85883 30.00 0.0035 NBFD30 10 41.6810 4.1398 1.80809 22.76 0.0212 FD225 11 306.5175 2.3629 12 -1737.0131 1.0000 1.90525 35.04 -0.0005 S-LAH93 13 77.4178 3.4603 14 -53.1292 1.0000 1.75500 52.32 -0.0069 TAC6 15 87.3948 3.6022 1.85451 25.15 0.0071 NBFD25 16 -191.2700 (d16) 17 297.0950 3.3431 1.74951 35.33 -0.0030 S-NBH51 18 -107.2797 0.3000 19 43.7870 6.2836 1.43700 95.10 0.0564 FCD100 20 -55.6235 1.0000 1.91082 35.25 -0.0028 TAFD35 21 446.6786 (d21) 22 80.0518 4.1365 1.80518 25.46 0.0131 FD60-W 23 -109.9320 0.3000 24 442.9234 1.0000 1.85883 30.00 0.0035 NBFD30 25 28.7632 5.0016 1.43700 95.10 0.0564 FCD100 26 910.3483 3.0900 27(Aperture) ∞ (d27) 28 65.8270 4.0898 1.72825 28.32 0.0101 E-FD10L 29 -62.3711 0.9500 1.94595 17.98 0.0385 FDS18-W 30 -219.2853 (d30) 31 -852.3860 3.0115 1.76182 26.61 0.0117 FD140 32 -59.5257 1.0000 1.90525 35.04 -0.0005 S-LAH93 33 49.1404 11.4117 34 1389.1992 5.7754 1.61340 44.27 -0.0054 S-NBM51 35 -25.8609 1.0000 1.43700 95.10 0.0564 FCD100 36 -204.0546 (d36) 37 54.4861 8.8965 1.61340 44.27 -0.0054 S-NBM51 38 -29.7135 1.0000 1.59282 68.62 0.0192 FCD515 39 149.3057 10.1058 40 -66.9926 1.0000 1.95375 32.32 -0.0002 TAFD45 41 363.5077 36.3723 42 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 43∞(BF) Image plane ∞ [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.75 8.63 4.78 Image height Y 21.63 21.63 21.63 Lens total length 280.00 330.89 377.31 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 21.0029 97.4866 161.2949 (d8) 27.6204 20.4903 3.1500 (d16) 35.1791 19.8671 2.0000 (d21) 15.1425 6.7001 2.6007 (d27) 18.3266 34.9186 56.5180 (d30) 16.5817 12.1923 3.3000 (d36) 2.0000 13.5519 22.8112 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 226.0348 G2 6 253.2497 G3 9 -33.9507 G4 17 101.9398 G5 22 220.0894 G6 28 84.3965 G7 31 -107.3394 G8 37 -164.4582 EXAMPLES

[0152] FIG. 85 is a lens arrangement diagram of a variable magnification image forming optical system according to Example 13 when focusing on an object at infinity at the wide-angle end.

[0153] The variable magnification imaging optical system in Figure 85 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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.

[0154] Starting from the object side, the first lens group G1 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 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, 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 cemented lens of a biconcave lens and 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 third lens in the third lens group G3 from the object side can be moved as a unit 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, and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, a cemented lens of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, and an aperture stop S. The sixth lens group G6 is composed of a cemented lens consisting 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 consisting of a convex meniscus lens with its convex surface facing the image side and a biconcave lens, and a cemented lens consisting 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 consisting of a biconvex lens and a biconcave lens, and a concave meniscus lens with its convex surface facing the image side.

[0155] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0156] 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) 1 306.6628 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 130.5805 9.9238 1.49700 81.61 0.0373 FCD1 3 -6951.8122 0.3000 4 137.3108 8.7688 1.43700 95.10 0.0564 FCD100 5 2338.3867 (d5) 6 167.7547 4.0390 1.58144 40.89 0.0019 E-FL5 7 -1954.6188 1.7000 1.49700 81.61 0.0373 FCD1 8 175.1337 1.5000 9 169.6310 6.1788 1.56732 42.84 0.0030 E-FL6 10 -105.8607 1.7000 1.72825 28.32 0.0084 E-FD10 11 -300.4857 (d11) 12 -224.8135 1.0000 1.91082 35.25 -0.0028 TAFD35 13 71.3341 3.0727 1.80809 22.76 0.0212 FD225 14 300.5576 2.3807 15 -1379.2002 1.0000 1.85150 40.78 -0.0055 S-LAH89 16 77.8516 3.3938 17 -53.5740 1.0000 1.75500 52.32 -0.0069 TAC6 18 90.0171 3.4158 1.85451 25.15 0.0071 NBFD25 19 -265.6314 (d19) 20 169.2468 3.4371 1.80440 39.59 -0.0042 S-LAH63 21 -126.4235 0.3000 22 49.0555 6.0091 1.43700 95.10 0.0564 FCD100 23 -53.4331 1.0000 1.91082 35.25 -0.0028 TAFD35 24 696.5137 (d24) 25 87.0510 4.1085 1.78472 25.72 0.0137 FD110 26 -98.7653 0.3000 27 1188.0144 1.0000 1.85883 30.00 0.0035 NBFD30 28 30.3381 4.9991 1.43700 95.10 0.0564 FCD100 29 -928.7335 2.9118 30(Aperture) ∞ (d30) 31 66.3030 4.0954 1.72825 28.32 0.0101 E-FD10L 32 -62.1744 0.9500 1.94595 17.98 0.0385 FDS18-W 33 -215.6741 (d33) 34 -301.1576 3.3432 1.85451 25.15 0.0071 NBFD25 35 -52.7203 1.0000 1.90525 35.04 -0.0005 S-LAH93 36 50.2694 6.8152 37 367.0535 5.4487 1.61340 44.27 -0.0054 S-NBM51 38 -25.2869 1.0000 1.43700 95.10 0.0564 FCD100 39 -533.7736 (d39) 40 50.7306 8.0631 1.61340 44.27 -0.0054 S-NBM51 41 -30.2850 1.0000 1.55032 75.50 0.0274 FCD705 42 117.9700 6.5728 43 -50.2478 1.0000 1.95375 32.32 -0.0002 TAFD45 44 -965.2571 38.0000 45 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 46∞(BF) Image plane ∞ [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.79 8.64 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 332.47 380.00 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 15.8228 74.2981 136.9794 (d11) 24.3066 18.2963 3.1500 (d19) 32.2015 20.3514 2.0000 (d24) 13.8205 5.3424 2.0000 (d30) 15.0291 27.0358 43.3110 (d33) 16.7118 11.9404 3.3000 (d39) 4.8802 17.9732 32.0322 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 241.0118 G2 6 205.0896 G3 12 -32.5983 G4 20 93.8120 G5 25 220.6743 G6 31 84.5376 G7 34 -95.6088 G8 40 -169.9590 EXAMPLES

[0157] FIG. 92 is a lens arrangement diagram of a variable magnification image forming optical system according to Example 14 when focusing on an object at infinity at the wide-angle end.

[0158] The variable magnification image forming optical system of Fig. 92 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 that focuses 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. Of these, the third lens group G3 and the eighth lens group G8 are fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.

[0159] Starting from the object side, the first lens group G1 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 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 biconcave lens and 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 third and subsequent lenses from the object side in the third lens group G3 can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. The fifth lens group G5 is composed of a biconvex lens, 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 an aperture stop S. The sixth lens group G6 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 seventh lens group G7 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 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 eighth lens group G8 is composed of a cemented lens made of a biconvex lens and a biconcave lens, and a concave meniscus aspheric lens with its convex surface facing the image side.

[0160] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0161] The values ​​of the specifications of the variable magnification imaging optical system according to the fourteenth embodiment are shown below. Numerical Example 14 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 253.2848 3.0000 1.61310 44.36 -0.0081 E-ADF10 2 118.9430 10.1341 1.49700 81.61 0.0373 FCD1 3 1887.0877 0.3000 4 137.6441 9.1404 1.43700 95.10 0.0564 FCD100 5 10228.1489 (d5) 6 170.8762 6.7225 1.71736 29.50 0.0082 E-FD1 7 -114.2974 1.7000 1.92286 20.88 0.0281 E-FDS1-W 8 -373.6553 (d8) 9 -224.3483 1.0000 1.91082 35.25 -0.0028 TAFD35 10 69.0925 3.1078 1.80809 22.76 0.0212 FD225 11 297.1757 2.5176 12 -454.3624 1.0000 1.90525 35.04 -0.0005 S-LAH93 13 83.6079 3.4436 14 -48.0498 1.0000 1.75500 52.32 -0.0069 TAC6 15 92.8465 3.7715 1.85451 25.15 0.0071 NBFD25 16 -135.0433 (d16) 17 237.3368 3.2071 1.80100 34.97 0.0009 S-LAM66 18 -141.9121 0.3000 19 43.7737 6.3705 1.43700 95.10 0.0564 FCD100 20 -56.7469 1.0000 1.91082 35.25 -0.0028 TAFD35 21 3805.1912 (d21) 22 80.3256 4.0955 1.80518 25.46 0.0131 FD60-W 23 -117.6519 0.3000 24 457.0641 1.0000 1.85883 30.00 0.0035 NBFD30 25 27.6341 5.1438 1.43700 95.10 0.0564 FCD100 26 875.6430 3.0938 27(Aperture) ∞ (d27) 28 61.0756 4.1833 1.72825 28.32 0.0101 E-FD10L 29 -60.3063 0.9500 1.94595 17.98 0.0385 FDS18-W 30 -256.7137 (d30) 31 -329.2939 9.4378 1.85451 25.15 0.0071 NBFD25 32 -61.3465 1.0004 1.85150 40.78 -0.0055 S-LAH89 33 43.7823 4.2514 34 -160.6308 6.3151 1.61310 44.36 -0.0081 E-ADF10 35 -17.8750 1.0000 1.55032 75.50 0.0274 FCD705 36 -73.8280 (d36) 37 56.2299 9.5046 1.55836 54.01 -0.0094 N-KZFS2 38 -29.7212 1.3818 1.55032 75.50 0.0274 FCD705 39 144.3063 13.2972 40* -53.9871 1.0000 1.95150 29.83 0.0008 M-TAFD405 41 -176.0155 35.5836 42 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 43∞(BF) Image plane ∞ [Aspheric data] 40 pages K 0.00000 A4 6.61650E-07 A6 1.00276E-09 A8 -1.86292E-12 A10 0.00000E+00 [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.79 8.65 4.20 Image height Y 21.63 21.63 21.63 Lens total length 280.00 332.23 379.52 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 12.5169 72.0135 138.0649 (d8) 29.1778 21.9086 3.1511 (d16) 37.3205 23.5560 2.0000 (d21) 8.4583 2.8291 4.1071 (d27) 15.9052 27.9162 45.3968 (d30) 11.8679 8.6091 3.6242 (d36) 2.0000 12.6414 20.4238 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 233.8285 G2 6 206.0302 G3 9 -33.1207 G4 17 90.1902 G5 22 296.1590 G6 28 83.4624 G7 31 -76.3267 G8 37 -275.4088 EXAMPLES

[0162] FIG. 99 is a lens configuration diagram of a variable magnification image forming optical system according to Example 15 when focusing on infinity at the wide-angle end.

[0163] The variable magnification image forming optical system of Fig. 99 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, an intermediate group GM consisting of a fourth lens group G4 and a fifth lens group G5, a focusing group GF consisting of a sixth lens group G6 for 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. Of these, the third lens group G3 and the eighth lens group G8 are fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.

[0164] Starting from the object side, the first lens group G1 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 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 biconcave lens and 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 third and subsequent lenses from the object side in the third lens group G3 can be moved as a unit 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 and a cemented lens of a biconvex lens and a biconcave lens. 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, a cemented lens of a biconcave lens and a biconvex lens, and an aperture stop S. The sixth lens group G6 is composed of a biconvex lens and a cemented lens of a concave meniscus lens with the convex surface facing the image side. The seventh lens group G7 is composed of a cemented lens of a biconvex lens 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 biconcave lens, and a biconcave lens.

[0165] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 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 second lens group G2 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 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 focusing group GF moves toward the object side along the optical axis.

[0166] The values ​​of the specifications of the variable magnification imaging optical system according to the fifteenth embodiment are shown below. Numerical Example 15 Unit: mm [Face data] Surface number rd nd vd ΔPgF Applicable glass material 0 (d0) 1 255.4417 3.0000 1.61340 44.27 -0.0054 S-NBM51 2 118.7656 10.2277 1.49700 81.61 0.0373 FCD1 3 2201.3932 0.3000 4 137.4395 9.0844 1.43700 95.10 0.0564 FCD100 5 5776.5179 (d5) 6 202.7920 6.3594 1.69895 30.05 0.0085 E-FD15 7 -109.0697 1.7000 1.92286 20.88 0.0281 E-FDS1-W 8 -297.2811 (d8) 9 -229.5220 1.0000 1.91082 35.25 -0.0028 TAFD35 10 62.3768 3.3923 1.80809 22.76 0.0212 FD225 11 380.5089 2.3247 12 -1320.8789 1.0000 1.90525 35.04 -0.0005 S-LAH93 13 74.0292 3.7438 14 -45.8825 1.0000 1.74320 49.34 -0.0065 S-LAM60 15 95.0636 3.8828 1.85451 25.15 0.0071 NBFD25 16 -119.4596 (d16) 17 147.0451 3.6466 1.69895 30.05 0.0085 E-FD15 18 -123.6922 0.3000 19 43.9252 6.3644 1.43700 95.10 0.0564 FCD100 20 -57.4734 1.0000 1.91082 35.25 -0.0028 TAFD35 21 241.9864 (d21) 22 86.2653 1.0000 1.66382 27.35 0.0328 J-SFH4 23 46.0728 5.1463 1.84666 23.78 0.0136 FDS90-SG 24 -107.7109 0.3000 25 -1282.7011 1.0000 1.85451 25.15 0.0071 NBFD25 26 27.8616 6.3211 1.43700 95.10 0.0564 FCD100 27 -370.3969 2.7789 28(Aperture) ∞ (d28) 29 63.0118 3.9635 1.75520 27.53 0.0102 E-FD4 30 -73.0385 0.9500 1.94595 17.98 0.0385 FDS18-W 31 -455.7269 (d31) 32 610.5637 2.4049 1.85478 24.80 0.0085 S-NBH56 33 -70.7573 0.9500 1.90525 35.04 -0.0005 S-LAH93 34 41.9984 2.8951 35 124.6585 6.2852 1.61310 44.36 -0.0081 E-ADF10 36 -19.9343 1.0000 1.55032 75.50 0.0274 FCD705 37 204.4563 (d37) 38 51.5589 12.0000 1.61310 44.36 -0.0081 E-ADF10 39 -41.8282 1.0000 1.43700 95.10 0.0564 FCD100 40 247.2013 7.5685 41 -54.6731 1.1000 1.95375 32.32 -0.0002 TAFD45 42 421.5895 38.0000 43 ∞ 2.5000 1.51680 64.20 0.0014 BSC7 44∞(BF) Image plane ∞ [Various data] Zoom ratio 3.78 Wide Angle Mid-Telephoto Focal length 153.00 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.72 8.65 4.20 Image height Y 21.63 21.63 21.63 Lens total length 280.00 331.25 378.65 [Variable interval data] Wide Angle Mid-Telephoto (d0) ∞ ∞ ∞ (d5) 14.8793 72.4427 138.6207 (d8) 28.2375 21.9267 3.1500 (d16) 31.4113 20.9862 2.0000 (d21) 14.0763 5.3735 2.0000 (d28) 16.6573 22.3457 40.3216 (d31) 16.2485 11.2087 3.3000 (d37) 2.0000 20.4793 32.7717 (BF) 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 234.5297 G2 6 223.1843 G3 9 -34.3018 G4 17 106.2491 G5 22 182.5277 G6 29 87.3049 G7 32 -66.1163 G8 38 -665.7355

[0167] The values ​​of the conditional expressions corresponding to the above-mentioned respective embodiments are shown below. [Conditional expression corresponding value] Condition formula / Example EX1 EX2 EX3 EX4 EX5 (1) 0.2 <f1 / fT<1.0 0.4 0.4 0.4 0.4 0.4 (2) 0.1 <f2 / fT<0.8 0.4 0.4 0.4 0.3 0.3 (3)1.3 <DG2Sw / DG2St<3.2 2.1 2.2 2.2 2.2 2.2 (4) ※ -0.8 -0.8 -0.8 -0.8 -0.8 (5) ΔPgFLg2>0.013 0.031 0.028 0.028 0.028 0.028 (6) 1.0 <f1 / fW<2.5 1.6 1.5 1.5 1.6 1.6 (7) ΔPgFLf>0.013 0.039 0.047 0.039 0.039 0.039 (8) 0.08 <fF / fT<0.25 0.14 0.15 0.14 0.14 0.14 (9) 1.0<νdLr×ΔPgfLr 2.1 2.1 2.1 1.3 1.3 (10)ΔPgFprAVE<-0.0035 -0.0054 -0.0054 -0.0054 -0.0054 -0.0054 Condition formula / Example EX6 EX7 EX8 EX9 EX10 (1) 0.2 <f1 / fT<1.0 0.4 0.4 0.4 0.4 0.5 (2) 0.1 <f2 / fT<0.8 0.4 0.4 0.3 0.4 0.4 (3)1.3 <DG2Sw / DG2St<3.2 2.3 2.1 1.7 2.1 1.6 (4) ※ -1.0 -0.8 -0.6 -0.8 -0.7 (5) ΔPgFLg2>0.013 0.028 0.028 0.039 0.028 0.028 (6) 1.0 <f1 / fW<2.5 1.7 1.5 1.6 1.7 1.7 (7) ΔPgFLf>0.013 0.039 0.039 0.028 0.039 0.039 (8) 0.08 <fF / fT<0.25 0.11 0.14 0.13 0.15 0.13 (9) 1.0<νdLr×ΔPgfLr 1.3 1.3 2.1 2.1 2.1 (10)ΔPgFprAVE<-0.0035 -0.0054 -0.0054 -0.0044 -0.0054 -0.0054 Conditional formula / Example EX11 EX12 EX13 EX14 EX15 (1) 0.2 <f1 / fT<1.0 0.4 0.4 0.4 0.4 0.4 (2) 0.1 <f2 / fT<0.8 0.4 0.4 0.4 0.4 0.4 (3)1.3 <DG2Sw / DG2St<3.2 2.3 2.2 2.0 2.1 2.1 (4) * -0.9 -1.0 -0.8 -0.8 -0.8 (5) ΔPgFLg2>0.013 0.028 0.045 0.037 0.028 0.028 (6) 1.0 <f1 / fW<2.5 1.5 1.5 1.6 1.5 1.5 (7) ΔPgFLf>0.013 0.039 0.019 0.039 0.039 0.039 (8) 0.08 <fF / fT<0.25 0.14 0.15 0.15 0.14 0.15 (9) 1.0<νdLr×ΔPgfLr 1.3 1.3 2.1 2.1 5.4 (10)ΔPgFprAVE<-0.0035 -0.0054 -0.0054 -0.0054 -0.0088 -0.0081 * -0.3>(g2hrW / Wih)-(g2hrT / Tih)>-1.5 [Explanation of symbols]

[0168] 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 GM intermediate group GF focusing group GR Successor Group S aperture stop I image plane

Claims

1. 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, an intermediate group GM consisting of one or more lens groups and including an aperture stop S, a focusing group GF having positive refractive power, and a subsequent group GR consisting of two or more lens groups, wherein the focusing group GF has one or more concave lenses that satisfy conditional expression (7), the lens group closest to the image side among the lens groups constituting the subsequent group GR includes at least one concave lens that satisfies conditional expression (9) below, a distance between adjacent lens groups changes during magnification or focusing, and the focusing group GF moves along the optical axis during focusing from an object at infinity to an object at a close distance. (7) ΔPgFLf>0.013 ΔPgFLf: anomalous dispersion of the concave lens constituting the focusing group GF (9) 1.0<νdLr×ΔPgFLr νdLr: Abbe number of the concave lens of the rear group GR ΔPgFLr: Anomalous dispersion of the concave lens of the rear group GR

2. 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, an intermediate group GM consisting of one or more lens groups and including an aperture stop S, a focusing group GF having positive refractive power, and a subsequent group GR consisting of two or more lens groups, wherein the focusing group GF has one or more concave lenses that satisfy conditional expression (7) and satisfies conditional expression (10), a spacing between adjacent lens groups changes during magnification or focusing, and the focusing group GF moves along the optical axis during focusing from an object at infinity to an object at a close distance. (7) ΔPgFLf>0.013 ΔPgFLf: anomalous dispersion of the concave lens constituting the focusing group GF (10)ΔPgFprAVE<-0.0035 ΔPgFprAVE: the average value of the anomalous dispersion of the two convex lenses that are closest to the image side and that constitute the rear group GR

3. 3. The variable magnification image forming optical system according to claim 1, wherein the concave lens arranged closest to the image side among the concave lenses constituting the focusing group GF has the largest positive anomalous dispersion.

4. 3. The variable magnification image forming optical system according to claim 1, wherein the focusing group GF satisfies the following condition (8): (8) 0.08<fF / fT<0.25 fF: focal length of the focusing group GF fT: focal length of the entire system at the infinity telephoto end

5. 2. The variable magnification imaging optical system according to claim 1, wherein the following condition is satisfied: (10)ΔPgFprAVE<-0.0035 ΔPgFprAVE: the average value of the anomalous dispersion of the two convex lenses that are closest to the image side and that constitute the rear group GR

6. 3. A variable magnification image forming optical system according to claim 1, wherein the lens group closest to the image side of said rear group GR is fixed with respect to the image plane during zooming.

7. 3. The variable magnification imaging optical system according to claim 1, wherein the following conditional expression (3) is satisfied: (3) 1.3<DG2Sw / DG2St<3.2 DG2Sw: the distance from the apex 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 lens closest to the object in the second lens group G2 at the telephoto end to the aperture stop S

8. 3. The variable magnification image forming optical system according to claim 1, wherein the second lens group G2 includes a concave lens that satisfies the following conditional expressions (4) and (5): (4) -0.3>(g2hrW / Wih)-(g2hrT / Tih)>-1.5 (5) ΔPgFLg2>0.013 g2hrW: the height of the off-axis chief ray on the front surface of the second lens group G2 at the infinity wide-angle end g2hrT: the height of the off-axis chief ray on the front surface of the second lens group G2 at the infinity telephoto end The off-axis chief ray is defined as a ray that passes through the point where the aperture position and the optical axis intersect. Wih: ray height on the image plane of the off-axis chief ray at the wide-angle end Tih: ray height on the image plane of the off-axis chief ray at the telephoto end ΔPgFLg2: anomalous dispersion of the concave lens having the largest anomalous dispersion among the concave lenses included in the second lens group G2

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