Variable magnification 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 use in imaging devices such as digital cameras and video cameras. [Background technology]

[0002] In recent years, as digital cameras, video cameras, and other devices have become increasingly mirrorless, smartphones and mobile data terminals have begun to be equipped with high-performance cameras. This has led to an increase in demand for ultra-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 also 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] For 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 zoom ratio to improve usability as a zoom lens, compact size to improve portability, and imaging performance.

[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 zooming, thereby increasing the telephoto ratio (the total optical length divided by the focal length) at the telephoto end as much as possible and improving imaging performance at telephoto positions.

[0008] Furthermore, in telephoto lenses, aberrations that occur in the converging lens group located on the object side are magnified by the lens groups behind them. With a prime lens, imaging performance can be improved by simply suppressing aberrations that occur in the converging lens group located on the object side based on this relationship, but with a zoom lens, various aberrations fluctuate due to changes in the power distribution caused by magnification changes, so this cannot be simplified like with a prime lens. Magnification chromatic aberration, which is particularly problematic in ultra-telephoto lenses with narrow angles of view, changes in the direction of occurrence as the magnification changes. Therefore, in order to achieve a compact optical system while suppressing magnification chromatic aberration across the entire zoom range, it is important to select optical materials that correspond to changes in the power distribution caused by magnification changes.

[0009] The optical system described in Patent Document 1 is an example of an ultra-telephoto zoom lens with a fixed overall length, and while it suppresses various aberrations throughout the entire zoom range and provides high imaging performance, attempting to increase the zoom ratio while maintaining imaging performance with a fixed overall length type like this would result in the optical system becoming significantly larger, which is not desirable.

[0010] The optical system described in Patent Document 2 is an example of an ultra-telephoto zoom lens with a variable overall length in which the first lens group extends, but the back focus (the distance from the final lens element to the image plane) is large relative to the overall optical length, and considering the short flange focal distances that have become common with mirrorless cameras in recent years, this is insufficient in terms of compactness of the optical system. Furthermore, there is a large fluctuation in lateral chromatic aberration from the wide-angle end to the telephoto end, and correction of this aberration 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 focal length, but the chromatic aberration of magnification varies significantly from the wide-angle end to the telephoto end, and correction is insufficient, and the overall optical length at the wide-angle end is also insufficiently reduced.

[0012] The present invention has been made in consideration of these problems, and its object is to provide a variable magnification imaging optical system that is compact and lightweight, suppresses chromatic aberration of magnification when zooming, has high-speed focusing with reduced performance degradation, and has good optical performance throughout the entire zoom range. [Means for solving the problem]

[0013] A variable magnification image forming optical system embodying the present invention, which is a means for solving the above-mentioned problems, 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, 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 formula (7), and the lens group of the subsequent group GR that is closest to the image side includes at least one or more concave lenses that satisfy conditional formula (9) below, the spacing between adjacent lens groups changes during magnification variation 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, 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 formula (7) and satisfy conditional formula (10), the spacing between adjacent lens groups changes during magnification variation 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 [Effects 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 with reduced performance degradation, and has good optical performance throughout the entire zoom range. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a lens configuration diagram of a variable magnification imaging optical system according to a first embodiment of the present invention at the wide-angle end when focusing on infinity. [Figure 2] FIG. 2 is a longitudinal aberration diagram of Example 1 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 3] FIG. 2 is a longitudinal aberration diagram of Example 1 of the variable magnification imaging optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 4] FIG. 2 is a longitudinal aberration diagram of Example 1 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 5]1A and 1B are diagrams illustrating lateral aberration when focusing on infinity at the wide-angle end according to Example 1 of the variable magnification image forming optical system of the present invention. [Figure 6] FIG. 2 is a diagram illustrating lateral aberration when the variable magnification imaging optical system according to Example 1 of the present invention is focused at infinity at an intermediate focal length. [Figure 7] FIG. 2 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 1 of the variable magnification image forming optical system of the present invention. [Figure 8] FIG. 10 is a lens configuration diagram of a variable magnification image forming optical system according to a second embodiment of the present invention at the wide-angle end when focusing on infinity. [Figure 9] FIG. 10 is a longitudinal aberration diagram of Example 2 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 10] FIG. 10 is a longitudinal aberration diagram of Example 2 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 11] FIG. 10 is a longitudinal aberration diagram of Example 2 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 12] FIG. 10 is a diagram illustrating lateral aberration at the wide-angle end of Example 2 of the variable magnification image forming optical system of the present invention when focused on infinity. [Figure 13] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 2 of the variable magnification image forming optical system of the present invention. [Figure 14] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 2 of the variable magnification image forming optical system of the present invention. [Figure 15] FIG. 10 is a lens configuration diagram of a variable magnification image forming optical system according to a third embodiment of the present invention when focused on infinity at the wide-angle end. [Figure 16] FIG. 10 is a longitudinal aberration diagram of Example 3 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 17] FIG. 10 is a longitudinal aberration diagram of Example 3 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 18] FIG. 10 is a longitudinal aberration diagram of Example 3 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 19] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the wide-angle end according to Example 3 of the variable magnification image forming optical system of the present invention. [Figure 20]FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 3 of the variable magnification image forming optical system of the present invention. [Figure 21] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 3 of the variable magnification image forming optical system of the present invention. [Figure 22] FIG. 10 is a lens configuration diagram of a variable magnification image forming optical system according to a fourth embodiment of the present invention at the wide-angle end when focusing on infinity. [Figure 23] FIG. 10 is a longitudinal aberration diagram of Example 4 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 24] FIG. 10 is a longitudinal aberration diagram of Example 4 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 25] FIG. 10 is a longitudinal aberration diagram of Example 4 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 26] FIG. 10 is a diagram illustrating lateral aberration at the wide-angle end of Example 4 of the variable magnification image forming optical system of the present invention when focused on infinity. [Figure 27] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 4 of the variable magnification imaging optical system of the present invention. [Figure 28] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 4 of the variable magnification image forming optical system of the present invention. [Figure 29] FIG. 10 is a lens configuration diagram of a variable magnification image forming optical system according to a fifth embodiment of the present invention at the wide-angle end when focusing on infinity. [Figure 30] FIG. 10 is a longitudinal aberration diagram of Example 5 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 31] FIG. 10 is a longitudinal aberration diagram of Example 5 of the variable magnification imaging optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 32] FIG. 10 is a longitudinal aberration diagram of Example 5 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 33] FIG. 10 is a lateral aberration diagram of Example 5 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 34] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 5 of the variable magnification imaging optical system of the present invention. [Figure 35]FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 5 of the variable magnification image forming optical system of the present invention. [Figure 36] FIG. 10 is a lens configuration diagram of a variable magnification imaging optical system according to Example 6 of the present invention when focused on infinity at the wide-angle end. [Figure 37] FIG. 10 is a longitudinal aberration diagram of Example 6 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 38] FIG. 10 is a longitudinal aberration diagram of Example 6 of the variable magnification imaging optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 39] FIG. 10 is a longitudinal aberration diagram of Example 6 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 40] FIG. 10 is a diagram illustrating lateral aberration at the wide-angle end of Example 6 of the variable magnification image forming optical system of the present invention when focused on infinity. [Figure 41] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 6 of the variable magnification imaging optical system of the present invention. [Figure 42] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 6 of the variable magnification image forming optical system of the present invention. [Figure 43] FIG. 10 is a lens configuration diagram of a variable magnification image forming optical system according to Example 7 of the present invention at the wide-angle end when focusing on infinity. [Figure 44] FIG. 10 is a longitudinal aberration diagram of Example 7 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 45] FIG. 10 is a longitudinal aberration diagram of Example 7 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 46] FIG. 10 is a longitudinal aberration diagram of Example 7 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 47] FIG. 10 is a diagram illustrating lateral aberration at the wide-angle end of Example 7 of the variable magnification image forming optical system of the present invention when focused on infinity. [Figure 48] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 7 of the variable magnification imaging optical system of the present invention. [Figure 49] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 7 of the variable magnification image forming optical system of the present invention. [Figure 50]FIG. 10 is a lens configuration diagram of Example 8 of a variable magnification imaging optical system according to the present invention at the wide-angle end when focusing on infinity. [Figure 51] FIG. 10 is a longitudinal aberration diagram of Example 8 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 52] FIG. 10 is a longitudinal aberration diagram of Example 8 of the variable magnification imaging optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 53] FIG. 10 is a longitudinal aberration diagram of Example 8 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 54] FIG. 10 is a diagram illustrating lateral aberration at the wide-angle end when focusing on infinity in Example 8 of the variable magnification image forming optical system of the present invention. [Figure 55] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 8 of the variable magnification imaging optical system of the present invention. [Figure 56] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 8 of the variable magnification image forming optical system of the present invention. [Figure 57] FIG. 10 is a lens configuration diagram of Example 9 of a variable magnification image forming optical system according to the present invention at the wide-angle end when focusing on infinity. [Figure 58] FIG. 13 is a longitudinal aberration diagram of Example 9 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 59] FIG. 10 is a longitudinal aberration diagram of Example 9 of the variable magnification image forming optical system of the present invention at an intermediate focal length when focused on infinity. [Figure 60] FIG. 10 is a longitudinal aberration diagram of Example 9 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 61] FIG. 10 is a diagram illustrating lateral aberration at the wide-angle end of Example 9 of the variable magnification image forming optical system of the present invention when focused on infinity. [Figure 62] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 9 of the variable magnification imaging optical system of the present invention. [Figure 63] FIG. 10 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 9 of the variable magnification image forming optical system of the present invention. [Figure 64] FIG. 16 is a lens configuration diagram of a variable magnification imaging optical system according to Example 10 of the present invention when focused on infinity at the wide-angle end. [Figure 65]FIG. 20 is a longitudinal aberration diagram of Example 10 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 66] FIG. 16 is a longitudinal aberration diagram of Example 10 of the variable magnification imaging optical system of the present invention when focused at infinity at an intermediate focal length. [Figure 67] FIG. 20 is a longitudinal aberration diagram of Example 10 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 68] FIG. 16 is a diagram illustrating lateral aberration at the wide-angle end when focusing on infinity in Example 10 of the variable magnification image forming optical system of the present invention. [Figure 69] FIG. 13 is a diagram illustrating lateral aberration when focusing at infinity at an intermediate focal length according to Example 10 of the variable magnification imaging optical system of the present invention. [Figure 70] FIG. 16 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end according to Example 10 of the variable magnification image forming optical system of the present invention. [Figure 71] FIG. 16 is a lens configuration diagram of an eleventh embodiment of a variable magnification imaging optical system according to the present invention when focused on infinity at the wide-angle end. [Figure 72] FIG. 16 is a longitudinal aberration diagram of Example 11 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 73] FIG. 16 is a longitudinal aberration diagram of Example 11 of the variable magnification imaging optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 74] FIG. 16 is a longitudinal aberration diagram of Example 11 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 75] FIG. 16 is a diagram illustrating lateral aberration at the wide-angle end when focusing on infinity in Example 11 of the variable magnification image forming optical system of the present invention. [Figure 76] FIG. 16 is a diagram illustrating lateral aberration when focusing at infinity at an intermediate focal length according to Example 11 of the variable magnification imaging optical system of the present invention. [Figure 77] FIG. 16 is a diagram illustrating lateral aberration when focusing on infinity at the telephoto end in Example 11 of the variable magnification image forming optical system of the present invention. [Figure 78] FIG. 20 is a lens configuration diagram of Example 12 of a variable magnification imaging optical system according to the present invention when focused on infinity at the wide-angle end. [Figure 79] FIG. 20 is a longitudinal aberration diagram of Example 12 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 80]FIG. 16 is a longitudinal aberration diagram of Example 12 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 81] FIG. 20 is a longitudinal aberration diagram of Example 12 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 82] FIG. 16 is a diagram illustrating lateral aberration at the wide-angle end when focusing on infinity in Example 12 of the variable magnification image forming optical system of the present invention. [Figure 83] FIG. 16 is a diagram illustrating lateral aberration when focusing at infinity at an intermediate focal length according to Example 12 of the variable magnification image forming optical system of the present invention. [Figure 84] FIG. 20 is a lateral aberration diagram of Example 12 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 85] FIG. 20 is a lens configuration diagram of Example 13 of a variable magnification imaging optical system according to the present invention when focused on infinity at the wide-angle end. [Figure 86] FIG. 20 is a longitudinal aberration diagram of Example 13 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 87] FIG. 20 is a longitudinal aberration diagram of Example 13 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 88] FIG. 20 is a longitudinal aberration diagram of Example 13 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 89] FIG. 20 is a lateral aberration diagram of Example 13 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 90] FIG. 13 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 13 of the variable magnification imaging optical system of the present invention. [Figure 91] FIG. 20 is a lateral aberration diagram of Example 13 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 92] FIG. 20 is a lens configuration diagram of Example 14 of a variable magnification imaging optical system according to the present invention when focused on infinity at the wide-angle end. [Figure 93] FIG. 20 is a longitudinal aberration diagram of Example 14 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 94] FIG. 20 is a longitudinal aberration diagram of Example 14 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 95]FIG. 20 is a longitudinal aberration diagram of Example 14 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 96] FIG. 20 is a lateral aberration diagram of Example 14 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 97] FIG. 20 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 14 of the variable magnification image forming optical system of the present invention. [Figure 98] FIG. 20 is a lateral aberration diagram of Example 14 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 99] FIG. 20 is a lens configuration diagram of Example 15 of a variable magnification image forming optical system according to the present invention at the wide-angle end when focusing on infinity. [Figure 100] FIG. 20 is a longitudinal aberration diagram of Example 15 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 101] FIG. 20 is a longitudinal aberration diagram of Example 15 of the variable magnification image forming optical system of the present invention when focused on infinity at an intermediate focal length. [Figure 102] FIG. 20 is a longitudinal aberration diagram of Example 15 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. [Figure 103] FIG. 20 is a lateral aberration diagram of Example 15 of the variable magnification image forming optical system of the present invention when focused on infinity at the wide-angle end. [Figure 104] FIG. 20 is a diagram illustrating lateral aberration when focusing on infinity at an intermediate focal length according to Example 15 of the variable magnification image forming optical system of the present invention. [Figure 105] FIG. 20 is a lateral aberration diagram of Example 15 of the variable magnification image forming optical system of the present invention when focused on infinity at the telephoto end. DETAILED DESCRIPTION OF THE INVENTION

[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 example is an example of the optical system of the present invention, and the present invention is not limited to this example without departing from the gist of the 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 embodiments, 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 defined as Ng, NF, Nd, and NC, respectively. The Abbe number νd, partial dispersion ratio PgF, and anomalous dispersion ΔPgF are defined as follows: νd = (Nd-1) / (NF-NC) PgF = (Ng-NF) / (NF-NC) ΔPgF = PgF-0.64833+0.00180×νd It is expressed as:

[0019] When counting the number of lenses in this application, 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 consisting of a convex lens and a concave lens is counted as two lenses.

[0020] Generally, the lateral chromatic aberration of an optical system composed of thin lenses is given as the sum of the chromatic aberrations 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 closer to the object than the aperture, the peripheral light beam passing through the lens passes through the quadrant opposite the image position, and with general optical glass, due to the dispersion characteristics, the longer the wavelength, the lower the image height at which light is formed, and the C-line is observed as lateral chromatic aberration in the under direction. Similarly, when a lens with negative refractive power is placed closer to the object than the aperture, the opposite phenomenon to the above occurs. Furthermore, when a lens is placed closer to the image than the aperture, the peripheral light beam passing through the lens and the image position pass through the same quadrant, resulting in the opposite phenomenon to when a lens is placed closer to the object than the aperture. (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 intersects with the optical axis.

[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, moves out significantly as the magnification changes from the wide-angle end to the telephoto end, and the distance from the aperture stop S increases, lateral chromatic aberration often occurs with the C-line overshooting at the wide-angle end and the C-line undershooting at the telephoto end, and fluctuates as the magnification changes. 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 imaging magnification between the g-line and C-line and other wavelengths, undesirable color bleeding such as reddish-purple appears at the outlines of the subject as a secondary spectrum.

[0023] This phenomenon occurs when the first lens group G1 extends as the magnification changes from the wide-angle side to the telephoto side, widening the distance from the aperture diaphragm S, and the lens groups from the second lens group G2 onwards move closer to the aperture diaphragm S. This causes a change in the power arrangement, which not only changes the lateral chromatic aberration that occurs in the first lens group G1, but also significantly changes the correction effect of 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-axial chief ray passes through a position higher and further away from the optical axis, and as shown in (Reference Equation 1), a change in ray height causes a change in lateral chromatic aberration.

[0024] Furthermore, in order to correct secondary spectra, it is effective to appropriately arrange glass materials with anomalous dispersion in accordance with changes in the correction effect of lateral chromatic aberration due to magnification change. For example, if the g-line and C-line are collected and secondary spectra become a problem between the d-line and the g-line, attempting to collect the d-line and C-line too much will result in insufficient correction for the g-line. However, by using glass materials with anomalous dispersion, it is possible to make up for the insufficient correction for the g-line, and as a result, it is possible to reduce secondary spectra. Below, an embodiment of the present invention that suppresses secondary spectra and effectively corrects lateral chromatic aberration throughout the entire zoom range will be described, focusing on correction for the g-line.

[0025] As can be seen from the numerical examples and the structural diagrams of each example, the variable magnification imaging optical system of the present invention comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, 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. The spacing between adjacent lens groups changes during magnification or focusing. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side and the second lens group G2 moves toward the image side, increasing the spacing between the first lens group G1 and the second lens group G2 and decreasing the spacing between the second lens group G2 and the third lens group G3, thereby achieving the main variable magnification effect of the variable magnification imaging optical system. The focusing group GF moves along the optical axis during focusing from an object at infinity to a close-up object.

[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, causing the off-axis chief ray that passes through a high position at the wide-angle end to pass through a lower position at the telephoto end, and the correction effect of the second lens group G2 for 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 element and glass with negative anomalous dispersion for the convex lens element, or both, are used in the second lens group G2, it will be possible to correct for the g-line in the under-correction direction at wide-angle positions, 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 stop S, has the effect of converging the light beam diverged by the third lens group G3 and controlling the height of the light rays incident on the focusing group GF to an appropriate height. This not only contributes to a reduction in the weight of the focusing group GF, but also plays a role in compensating for the image plane during zooming.

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

[0030] The trailing group GR, which consists of one or more lens groups, is responsible for image plane compensation and for correcting lateral chromatic aberration, which becomes significant at the telephoto end. By using glass with positive anomalous dispersion for the concave lenses in the trailing group GR and glass with negative anomalous dispersion for the convex lenses, it is possible to correct the g-line in the over-correction direction, making it possible to correct lateral chromatic aberration at the telephoto end. Furthermore, because on-axis rays pass through the trailing group GR at a lower ray height than off-axial chief rays, the correction effect of lateral chromatic aberration tends to increase at higher image heights.

[0031] On the other hand, if lateral chromatic aberration on the telephoto side is corrected by using glass with positive anomalous dispersion for the concave lens elements and glass with negative anomalous dispersion for the convex lens elements in the subsequent lens group GR, the g-line will be over-corrected on the wide-angle side, worsening lateral chromatic aberration. However, by offsetting the worsening lateral chromatic aberration on the wide-angle side with the correction effect of lateral chromatic aberration in the second lens group G2, which has a significant correction effect on the g-line in the under-correction side on the wide-angle side, it becomes possible to effectively correct lateral chromatic aberration 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 telephoto end

[0033] Conditional formula (1) that must be satisfied by the variable magnification imaging optical system of the present invention defines 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 expression (1) is exceeded and the focal length of the first lens group G1 becomes longer than the focal length of the entire system at the infinity telephoto end, the total optical length at the telephoto end becomes too long, increasing the amount of movement of the first lens group G1 during zooming, complicating the movement mechanism and resulting in an increase in the size of the lens barrel.

[0035] If the lower limit of conditional expression (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 becomes too high, making it difficult to correct various aberrations such as axial chromatic aberration at the telephoto end.

[0036] As for conditional expression (1), it is preferable to set the lower limit to 0.3 and the upper limit to 0.7, thereby making it possible to ensure the above-mentioned effect.

[0037] Similarly, in the variable magnification imaging optical system of the present invention, it is desirable to satisfy the following conditional expression (2) in order to achieve both a reduction in the overall length of the optical system and high performance. (2) 0.1 <f2 / fT<0.8 f2: the focal length of the second lens group G2 fT: focal length of the entire system at the telephoto end

[0038] Conditional formula (2) that must be satisfied by the variable magnification imaging optical system of the present invention defines 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 expression (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 an attempt is made to forcibly shorten the overall length by compensating 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 improve performance.

[0040] If the lower limit of conditional expression (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, particularly at the wide-angle end where the off-axis chief ray passes through a high position, and making it difficult to achieve high performance.

[0041] As for conditional expression (2), it is desirable to set the lower limit to 0.2 and the upper limit to 0.6, thereby making it possible to ensure the above-mentioned effect.

[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 chromatic aberration of magnification over the entire zoom range. (3)1.3 <DG2Sw / DG2St<3.2 DG2Sw: the distance from the apex of the surface 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 surface 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 between the apex of the surface of the lens closest to the object in the second lens group G2 and the aperture stop S at the wide-angle end and the telephoto end. As mentioned above, when changing magnification from the wide-angle end to the telephoto end, the second lens group G2 of the variable magnification imaging optical system of the present invention moves toward the image side, reducing the distance between it and the third lens group G3, thereby reducing the distance between it and the aperture stop S included in the middle group GM. It is desirable that the effect of correction of lateral chromatic aberration by the second lens group G2 be greater at the wide-angle end and smaller at the telephoto end. Therefore, it is desirable that the second lens group G2 be closer to the aperture stop S at the telephoto end and that the height of the off-axial chief ray passing through the second lens group G2 be lower.

[0044] If the lower limit of conditional expression (3) is exceeded, and the ratio between the distance from the apex of the surface of the lens closest to the object in second lens group G2 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 second lens group G2 becomes small, and the change in the correction effect of lateral chromatic aberration becomes small, making it difficult to effectively correct lateral chromatic aberration throughout the entire zoom range, which is undesirable.

[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 closest to the object in the second lens group G2 to the diaphragm at the wide-angle end and the telephoto end becomes large, the amount of movement of the second lens group G2 due to magnification change becomes large, causing the off-axial light beam at the wide-angle end to pass through a higher position, which is undesirable as it leads to an increase in the outer diameter of the second lens group G2.

[0046] As for conditional expression (3), it is desirable to set the lower limit to 1.4 and the upper limit to 2.6, thereby making it possible to ensure the above-mentioned effect.

[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 during zooming from the wide-angle end to the telephoto end, plays an important role in effectively correcting the chromatic aberration of magnification 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 at the front surface of the second lens group G2 at the infinity wide-angle end g2hrT: Height of the off-axis chief ray at the front surface of the second lens group G2 at the infinity telephoto end The definition of the off-axis chief ray is 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 with the largest anomalous dispersion among the concave lenses included in the second lens group G2

[0048] Conditional expression (4) defines a desirable range for the difference between the ratio of the height of the off-axial chief ray at the front surface of 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 front surface of second lens group G2 at the infinity telephoto end to the image height formed by the off-axial chief ray at the telephoto end. As this difference increases toward 0, it means that the change in the off-axial chief ray at second lens group G2 when zooming from the infinity wide-angle end to the infinity telephoto end is small. Conversely, as the difference decreases toward 0, it means that the change in the off-axial chief ray at 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 front surface of 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 front surface of second lens group G2 at the infinity telephoto end to the image height formed by the off-axial chief ray at the telephoto end increases and approaches 0, the change in the off-axial chief ray at second lens group G2 when zooming from the infinity wide-angle end to the infinity telephoto end will be small, the correction effect of lateral chromatic aberration will be small, and lateral chromatic aberration will not be sufficiently corrected either on the wide-angle side or the telephoto side, which is undesirable.

[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 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 wide-angle end and the ratio of the height of the off-axial chief ray at 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 telephoto end decreases away from 0, the change in the off-axial chief ray at the second lens group G2 becomes too large when zooming from the infinity wide-angle end to the infinity telephoto end, making it difficult to correct astigmatism and field curvature, which is undesirable.

[0051] As for conditional expression (4), it is preferable to set the lower limit to -1.3 and the upper limit to -0.4, thereby making it possible to ensure the above-mentioned effect.

[0052] Conditional formula (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 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-axial chief ray that passes through the second lens group G2 passes through a higher position at the wide-angle end and a lower position at the telephoto end. In order to suppress lateral chromatic aberration and achieve high performance across the entire zoom range, the second lens group G2 needs to compensate more for the g-line toward under-correction at the wide-angle end. Therefore, a larger ΔPgF and greater positive anomalous dispersion are advantageous for compensating for the g-line.

[0054] If the lower limit of conditional expression (5) is exceeded and anomalous dispersion becomes small, the effect of under-correcting the g-line at wide-angle positions decreases, making it difficult to suppress lateral chromatic aberration and achieve high performance across the entire zoom range.

[0055] As for conditional expression (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 more reliably.

[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) defines 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 conditional expression (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 conditional expression (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 becomes 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 undesirable.

[0060] As for conditional expression (6), it is desirable to set the upper limit to 1.9 and the lower limit to 1.3, thereby making it possible to ensure the above-mentioned effect.

[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 variation, thereby preventing the mechanism from becoming complicated. This is preferable because if a portion 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 variation.

[0062] As can be seen from the numerical examples and the structural diagrams of each example, the variable magnification image forming optical system of the present invention is an optical system that 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 characterized in that the spacing between adjacent lens groups changes when varying magnification, and 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 imaging optical system of the present invention, in order to achieve high performance with correction of lateral chromatic aberration throughout the entire zoom range, it is desirable that the focusing group GF 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 lenses that make up the focusing group GF

[0064] Conditional formula (7) defines the range of anomalous dispersion of the concave lens that is desirably included in at least one focusing group GF. In a variable magnification optical system according to the present invention, the imaging magnification of light rays with short wavelengths, particularly those shorter than the g-line, decreases on the telephoto side, leaving lateral chromatic aberration in the under-focus 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.

[0065] If the lower limit of conditional expression (7) is exceeded and the anomalous dispersion of the concave lens elements constituting the focusing group GF 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.

[0066] It should be noted that the lower limit of conditional expression (7) is preferably set to 0.018, more preferably 0.020, which makes it possible to ensure the above-mentioned effect.

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

[0068] In the variable magnification imaging optical system of the present invention, it is desirable to satisfy the following conditional expression (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 telephoto end

[0069] A shorter movement distance of the focusing group GF from infinity to the close-up position has the advantage of improving focusing speed, but it requires increasing the power of the focusing group GF, which is undesirable as it results in a significant degradation of performance during focusing. With this in mind, conditional expression (8) defines 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-to-telephoto position in order to increase focusing speed and minimize degradation of performance during focusing.

[0070] If the lower limit of conditional expression (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, and the distance that the focusing group GF must move from infinity to the close-up position will become long, resulting in an undesirable decrease in focusing speed.

[0071] If the upper limit of conditional expression (8) is exceeded and the ratio between the focal length of the focusing group GF and the focal length of the entire system at the infinity telephoto end becomes large, the power of the focusing group GF becomes too strong, which undesirably increases performance fluctuations due to the deterioration of various aberrations during focusing.

[0072] As for conditional expression (8), it is preferable to set the lower limit to 0.10 and the upper limit to 0.20, thereby making it possible to more reliably achieve the above-mentioned effect.

[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 that satisfies the following conditional expression (9): 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. (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) defines the relationship between the Abbe number and anomalous dispersion of a concave lens, which is desirably included in at least one of the lens groups constituting the subsequent group GR in the variable magnification imaging optical system of the present invention, closest to the image. In the variable magnification imaging optical system of the present invention, short wavelength light rays, particularly those shorter than the g-line, are undercorrected on the telephoto side, resulting in a decrease in imaging magnification and the remaining lateral chromatic aberration in the under-correction 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 conditional expression (9) is exceeded and the anomalous dispersion of the concave lens element constituting the subsequent lens 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] It should be noted that the lower limit of conditional expression (9) is preferably set to 1.3, more preferably 1.8, so that the above-mentioned effect can be more reliably achieved.

[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 the lenses constituting the subsequent group GR satisfy the range defined by 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) defines the average value of the anomalous dispersion of the two convex lenses closest to the image side that make up the subsequent group GR in the variable magnification image forming optical system of the present invention, and in the variable magnification image forming optical system of the present invention, the imaging magnification of light rays with short wavelengths, particularly light rays from the g-line onwards, 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 conditional expression (10) is exceeded and the anomalous dispersion of the two convex lenses furthest from the image side that make up the subsequent group becomes large, the effect of over-correcting the g-line at the telephoto position decreases, making it difficult to suppress lateral chromatic aberration throughout the entire zoom range.

[0080] As for conditional expression (10), it is preferable to set the upper limit to -0.0050, thereby making it possible to ensure the above-mentioned effect.

[0081] In the variable magnification image forming optical system of the present invention, in order to ensure reliable overcorrection of g-line by the subsequent lens group GR on the telephoto side, it is necessary to keep the height of peripheral light flux passing through the second lens group G2, which has the effect of correcting g-line on the undercorrection side, low on the telephoto side, and to achieve this, it is necessary for the second lens group G2 to move closer to the third lens group G3 and subsequent lens groups when changing magnification from the wide-angle end to the telephoto end. Therefore, it is desirable that, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side and the second lens group G2 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 imaging optical system of the present invention, in order to prevent the mechanical mechanism from becoming complicated, it is desirable that the lens unit closest to the image side among the subsequent lens units GR be fixed relative 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, in which the lens configurations are listed 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 spacing 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. Additionally, 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 aspherical due to its shape. BF indicates the back focus, and the object surface distance indicates 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] [Aspherical Surface Data] shows the values ​​of each coefficient that determines the aspherical shape of lens surfaces marked with an * in [Surface Data]. The shape of an aspherical surface is expressed by the following formula. In the formula below, y represents the displacement from the optical axis in a direction perpendicular to the optical axis, z represents the displacement (amount of deviation) from the intersection of the aspherical surface and the optical axis in the direction of the optical axis, r represents the radius of curvature of the reference sphere, and K represents the Conic coefficient. Additionally, A4, A6, A8, and A10 represent the aspherical coefficients of the 4th, 6th, 8th, and 10th orders, respectively. TIFF0007743116000001.tif18124

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

[0089] [Variable Distance Data] shows the variable distance and BF values ​​for various shooting distance and focus states.

[0090] [Lens Group Data] shows the lens numbers of the lenses that make up each lens group closest to the object and the composite focal length of the entire group.

[0091] In the aberration diagrams corresponding to the respective examples, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image surface and 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, this is not a limitation, as optical systems can achieve similar optical performance with proportional magnification and proportional reduction. [Example]

[0092] FIG. 1 is a lens configuration diagram of a variable magnification imaging optical system according to Example 1 when focused on infinity at the wide-angle end.

[0093] The variable magnification image-forming optical system in FIG. 1 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-up 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 consists of a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and a convex meniscus lens with its convex surface facing the object side. The second lens group G2 consists of a biconvex aspherical lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with its convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and an aperture stop S. 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 consists of a cemented lens consisting of a biconvex lens and a biconcave lens, and a cemented lens consisting 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 consists 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.

[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 specifications of the variable magnification imaging optical system according to Example 1 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 ∞ [Aspherical 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-range 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-range 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 [Example]

[0097] FIG. 8 is a lens configuration diagram of a variable magnification imaging optical system according to Example 2 when focused on infinity at the wide-angle end.

[0098] The variable magnification imaging optical system in Figure 8 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.

[0099] Starting from the object side, the first lens group G1 consists of a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with a convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element from the object side onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting 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 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 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 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 consists of a cemented lens consisting of a biconvex lens and a convex meniscus lens with its convex surface facing the image side, and a concave meniscus aspherical 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 specifications of the variable magnification imaging optical system according to Example 2 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 ∞ [Aspherical 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-range 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-range 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 [Example]

[0102] FIG. 15 is a lens configuration diagram of a variable magnification imaging optical system according to Example 3 when focused on infinity at the wide-angle end.

[0103] The variable magnification imaging 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 an object at a close distance, and a subsequent group GR consisting of a seventh lens group G7 and an eighth lens group G8.

[0104] Starting from the object side, the first lens group G1 consists of a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and a convex meniscus lens with its convex surface facing the object side. The second lens group G2 consists of a cemented lens consisting of a biconvex lens and a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with its convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third and subsequent lenses in the third lens group G3 from the object side can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting of a biconcave lens and a biconvex lens, and an aperture stop S. 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 cemented lens consisting of a biconvex lens and a biconcave lens, and a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a biconcave lens, and a concave meniscus aspherical 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 specifications of the variable magnification imaging optical system according to Example 3 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 ∞ [Aspherical 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-range 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-range 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 [Example]

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

[0108] The variable magnification image forming optical system shown in Figure 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, 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. 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] Starting from the object side, the first lens group G1 consists of a biconvex lens, a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a convex meniscus lens with its convex surface facing the object side, and a convex meniscus lens with its convex surface facing the object side. The second lens group G2 consists of a biconvex lens and a cemented lens consisting of a concave meniscus lens with its convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with its convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element from the object side onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and an aperture stop S. 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 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 consists of a cemented lens consisting 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 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-range 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-range 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 [Example]

[0112] FIG. 29 is a lens configuration diagram of a variable magnification image forming optical system according to Example 5 when focused on 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 consists of a convex meniscus lens with a convex surface facing the object side, a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with a convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element from the object side onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting 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 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 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 consists of a cemented lens consisting 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 specifications of the variable magnification imaging optical system according to Example 5 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 ∞ [Aspherical 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-range 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-range 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 [Example]

[0117] FIG. 36 is a lens configuration diagram of a variable magnification image forming optical system according to Example 6 when focused on infinity at the wide-angle end.

[0118] The variable magnification imaging optical system in Figure 36 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.

[0119] Starting from the object side, the first lens group G1 consists of a biconvex lens, a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a convex meniscus lens with its convex surface facing the object side, and a convex meniscus lens with its convex surface facing the object side. The second lens group G2 consists of a biconvex lens and a cemented lens consisting of a concave meniscus lens with its convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with its convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element from the object side onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a convex meniscus lens with its convex surface facing the object side, and an aperture stop S. 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, and 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 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 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 consists 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.

[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 specifications of the variable magnification imaging optical system according to Example 6 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-range 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 total length 310.82 380.37 424.11 [Variable Interval Data] Wide-angle Mid-range 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 [Example]

[0122] FIG. 43 is a lens configuration diagram of a variable magnification image forming optical system according to Example 7 when focused on 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 close range, 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 consists of a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting 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 consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element from the object side onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a cemented lens consisting of a biconvex lens and a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The fifth lens group G5 consists of a cemented lens consisting 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 consisting of a biconcave lens and a biconvex lens, and an aperture stop S. The seventh lens group G7 consists of 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 consists 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 biconcave lens. The ninth lens group G9 consists 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.

[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, and 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 toward the object along the optical axis.

[0126] The specifications of the variable magnification imaging optical system according to Example 7 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-range 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-range 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 [Example]

[0127] FIG. 50 is a lens configuration diagram of a variable magnification imaging optical system according to Example 8 when focused on infinity at the wide-angle end.

[0128] The variable magnification imaging optical system in Figure 50 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 close range, 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 consists of a cemented lens consisting 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 consists of a cemented lens consisting 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 consists 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 consisting of a biconcave lens and a convex meniscus lens with a convex surface facing the object side. The third and subsequent lenses in the third lens group G3 from the object side can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a cemented lens consisting of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, a biconvex lens, and a cemented lens consisting 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 aspherical 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 cemented lens consisting 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 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 specifications of the variable magnification imaging optical system according to Example 8 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 ∞ [Aspherical 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-range 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 total length 277.57 322.64 374.90 [Variable Interval Data] Wide-angle Mid-range 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 [Example]

[0132] FIG. 57 is a lens configuration diagram of a variable magnification imaging optical system according to Example 9 when focused on infinity at the wide-angle end.

[0133] The variable magnification imaging optical system of Figure 57 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 close range, 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 consists of a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting 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 consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element from the object side onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a cemented lens consisting of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting 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 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 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 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 consists of a cemented lens consisting 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 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-range 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 total length 269.94 332.78 369.94 [Variable Interval Data] Wide-angle Mid-range 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 [Example]

[0137] FIG. 64 is a lens configuration diagram of a variable magnification imaging optical system according to Example 10 when focused on infinity at the wide-angle end.

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

[0139] Starting from the object side, the first lens group G1 consists of a biconvex lens, a cemented lens consisting 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 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The third lens group G3 consists of a biconcave lens and a cemented lens consisting of a convex meniscus lens with a convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens, a cemented lens consisting of a biconvex lens and a biconcave lens, a biconvex lens, a cemented lens consisting of a biconvex lens and a biconcave lens, and an aperture stop S. The fifth lens group G5 consists of a biconvex lens and a cemented lens consisting of a concave meniscus lens with a convex surface facing the image side. The sixth lens group G6 consists of a cemented lens consisting of a biconvex lens and a biconcave lens, and a cemented lens consisting of a biconvex lens and a biconcave lens. The seventh lens group G7 consists 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.

[0140] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 and the seventh lens group G7 remain 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 a close object, the focusing group GF moves toward the object side along the optical axis.

[0141] The specifications of the variable magnification imaging optical system according to Example 10 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-range 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-range 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 [Example]

[0142] FIG. 71 is a lens configuration diagram of a variable magnification image forming optical system according to Example 11 when focused on infinity at the wide-angle end.

[0143] The variable magnification image forming optical system of Figure 71 is composed of, from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, 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. 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 consists of a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and a convex meniscus lens with its convex surface facing the object side. The second lens group G2 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with its convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with its convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element from the object side onwards, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and an aperture stop S. 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 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 consists 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 specifications of the variable magnification imaging optical system according to Example 11 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-range 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-range 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 [Example]

[0147] FIG. 78 is a lens configuration diagram of a variable magnification image forming optical system according to Example 12 when focused on infinity at the wide-angle end.

[0148] The variable magnification imaging optical system of 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 consists of a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with a convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element toward the object side, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting 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 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 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 consists of a cemented lens consisting 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 Example 12 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-range 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-range 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 [Example]

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

[0153] The variable magnification imaging optical system of Figure 85 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 close range, 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 consists of a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and a convex meniscus lens with its convex surface facing the object side. The second lens group G2 consists of a cemented lens consisting of a biconvex lens 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 third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with its convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element toward the object side, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting of a concave meniscus lens with its convex surface facing the object side and a biconvex lens, and an aperture stop S. 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 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 consists 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 specifications of the variable magnification imaging optical system according to Example 13 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-range 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-range 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 [Example]

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

[0158] The variable magnification image forming optical system of Figure 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 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.

[0159] Starting from the object side, the first lens group G1 consists of a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with a convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third lens group G3, from the third lens element toward the object side, can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a biconvex lens, a cemented lens consisting 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 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 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 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 consists of a cemented lens consisting of a biconvex lens and a biconcave lens, and a concave meniscus aspherical 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 specifications of the variable magnification imaging optical system according to Example 14 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 ∞ [Aspherical 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-range 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-range 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 [Example]

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

[0163] The variable magnification image forming optical system of Figure 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 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.

[0164] Starting from the object side, the first lens group G1 consists of a cemented lens consisting 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 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with a convex surface facing the image side. The third lens group G3 consists of a cemented lens consisting of a biconcave lens and a convex meniscus lens with a convex surface facing the object side, a biconcave lens, and a cemented lens consisting of a biconcave lens and a biconvex lens. The third and subsequent lenses in the third lens group G3 from the object side can be moved as a unit perpendicular to the optical axis to function as an image stabilization group. The fourth lens group G4 consists of a biconvex lens and a cemented lens consisting of a biconvex lens and a biconcave lens. The fifth lens group G5 consists of a cemented lens consisting of a concave meniscus lens with a convex surface facing the object side and a biconvex lens, a cemented lens consisting of a biconcave lens and a biconvex lens, and an aperture stop S. The sixth lens group G6 consists of a cemented lens consisting of a biconvex lens and a concave meniscus lens with the convex surface facing the image side. The seventh lens group G7 consists of a cemented lens consisting of a biconvex lens and a biconcave lens, and a cemented lens consisting of a biconvex lens and a biconcave lens. The eighth lens group G8 consists of a cemented lens consisting 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 specifications of the variable magnification imaging optical system according to Example 15 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-range 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-range 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 ​​corresponding to the conditional expressions for each of the above embodiments are shown below. [Conditional expression corresponding value] Conditional 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 Conditional 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 Second lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group G8 8th lens group G9 9th lens group GM intermediate group GF focusing group GR successor group S aperture stop I image plane

Claims

1. a focusing group GF 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 the lens group closest to the image side of the lens groups constituting the subsequent group GR includes at least one or more concave lenses that satisfy conditional expression (9): (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 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 wherein conditional expression (10) is satisfied, wherein 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 are closest to the image side and that constitute the subsequent lens group GR

3. 3. A variable magnification imaging 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. A variable magnification image-forming optical system according to claim 1, wherein the focusing group GF satisfies the following conditional expression (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. A 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 subsequent lens group GR

6. 3. A variable magnification imaging optical system according to claim 1, wherein the lens group closest to the image side in the rear group GR is fixed relative 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 to the aperture stop S at the wide-angle end 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 imaging 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): ##EQU4## where: .times. ... (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 definition of the off-axis chief ray is 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 with the largest anomalous dispersion among the concave lenses included in the second lens group G2

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