Zooming imaging optical system

Abstract

The invention provides a variable magnification imaging optical system, which realizes miniaturization and light weight, suppresses magnification chromatic aberration and axial chromatic aberration during magnification change, can realize high speed during focusing, and has good optical performance from infinity to extremely near in the whole zoom area. A variable magnification imaging optical system according to the present invention comprises, 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) comprising one or more lens groups and an aperture stop (S), a focusing group (GF), and a subsequent group (GR) comprising one lens group. The distance between adjacent lens groups varies during zooming, and the focusing group (GF) moves along the optical axis when focusing from an object at infinity to an object at a close distance.

Description

Technical Field

[0001] This invention relates to a zoom imaging optical system suitable for use in imaging devices such as digital cameras or camcorders. Background Technology

[0002] In recent years, mirrorless cameras and camcorders have continued to develop, and high-performance cameras have been integrated into smartphones and mobile data terminals. In order to differentiate digital cameras and camcorders from these mobile devices, the demand for super telephoto zoom lenses has been increasing.

[0003] Furthermore, in recent years, the pixel count of image sensors in digital cameras or camcorders has further increased, leading to a greater demand for high-performance image optical systems.

[0004] Patent documents 1 to 3 describe examples of zoom imaging optical systems with a half field of view of approximately 3 degrees or less at the far end.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-167749 Patent Document 2: Japanese Patent Application Publication No. 2016-080825 Patent Document 3: Japanese Patent Application Publication No. 2019-020450

[0006] In super telephoto zoom lenses with narrow field of view at the telephoto end, in order to improve the ease of use as a zoom lens, it is necessary to balance three points: taking the largest possible zoom ratio, miniaturization to improve portability, and imaging performance.

[0007] To achieve a larger zoom ratio, a lens group with positive refractive power is usually placed on the side closest to the object, and then pushed to the object side by zooming, thereby maximizing the zoom ratio (total optical length divided by focal length) at the telephoto end and improving the imaging performance when telephoto.

[0008] Furthermore, in telephoto lenses, aberrations generated in the lens group of the converging system located on the object side are amplified in the lens group behind it. With a single-focus lens, imaging performance can be improved by simply suppressing aberrations generated in the converging system on the object side based on this relationship. However, in zoom lenses, aberrations change due to variations in optical power configuration caused by magnification, making the process less straightforward than with a single-focus lens. In particular, chromatic aberration, a problem in super-telephoto lenses with narrow field of view, changes in direction due to magnification. Therefore, to suppress chromatic aberration throughout the zoom range while miniaturizing the optical system, it is crucial to select optical materials based on the changes in optical power configuration caused by magnification.

[0009] The optical system described in Patent Document 1 is an example of a super telephoto zoom lens with a fixed total length. While it suppresses aberrations and achieves high imaging performance across the entire zoom range, increasing the zoom ratio while maintaining imaging performance with a fixed total length results in a significantly larger optical system, which is therefore not preferred.

[0010] The optical system described in Patent Document 2 is an example of a variable-length super telephoto zoom lens introduced in Group 1. However, its back focal length (distance from the final lens to the image plane) is large relative to the total optical length. Considering the shortening of the flange distance caused by the recent trend towards mirrorless lenses, it is insufficient in terms of miniaturization of the optical system. Furthermore, the variation in chromatic aberration from the wide-angle end to the telephoto end is large, and the correction is insufficient.

[0011] The optical system described in Patent Document 3 is an example of a super telephoto zoom lens corresponding to a short flange distance, but the magnification chromatic aberration varies greatly from the wide-angle end to the telephoto end, the correction is insufficient, and the suppression of the total optical length at the wide-angle end is also insufficient. Summary of the Invention

[0012] The present invention was made in view of this problem, and its purpose is to provide a zoom imaging optical system that, while achieving miniaturization and lightweighting, suppresses magnification chromatic aberration and on-axis chromatic aberration during zooming, enables high-speed focusing, and has good optical performance throughout the zoom range from infinity to near.

[0013] To address the aforementioned issues, in one embodiment of the zoom imaging optical system of the present invention, the system comprises, sequentially arranged from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM including one or more lens groups and an aperture stop S, a focusing group GF, and a subsequent group GR consisting of one lens group. The spacing between adjacent lens groups changes during zooming, and when focusing from an object at infinity to a closer object, the focusing group GF moves along the optical axis. Invention Effects

[0014] According to at least a few embodiments of the present invention, a zoom imaging optical system is provided that, while achieving miniaturization and lightweighting, suppresses magnification chromatic aberration and on-axis chromatic aberration during zooming, enables high-speed focusing, and possesses good optical performance throughout the zoom range from infinity to near. Attached Figure Description

[0015] Figure 1 This is a lens structure diagram of the wide-angle end when focusing at infinity, according to Embodiment 1 of the zoom imaging optical system of the present invention. Figure 2This is a longitudinal aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 1 of the zoom imaging optical system of the present invention. Figure 3 This is a longitudinal aberration diagram of the intermediate focal length at infinity when focusing, according to Embodiment 1 of the zoom imaging optical system of the present invention. Figure 4 This is a longitudinal aberration diagram of the telephoto end when focusing at infinity, according to Embodiment 1 of the zoom imaging optical system of the present invention. Figure 5 This is a lateral aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 1 of the zoom imaging optical system of the present invention. Figure 6 This is a lateral aberration diagram of the intermediate focal length at infinity when focusing, according to Embodiment 1 of the zoom imaging optical system of the present invention. Figure 7 This is a lateral aberration diagram of the telescope at infinity focusing, as described in Embodiment 1 of the zoom imaging optical system of the present invention. Figure 8 This is a lateral aberration diagram of the wide-angle end of the zoom imaging optical system of the present invention when focusing at a distance of 2.5m from the object. Figure 9 This is a lateral aberration diagram of an object at a distance of 2.5m at the intermediate focal length, as described in Embodiment 1 of the zoom imaging optical system of the present invention. Figure 10 This is a lateral aberration diagram of the telescope at a distance of 2.5m when focusing, according to Embodiment 1 of the zoom imaging optical system of the present invention. Figure 11 This is a lens structure diagram of the wide-angle end when focusing at infinity, according to Embodiment 2 of the zoom imaging optical system of the present invention. Figure 12 This is a longitudinal aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 2 of the zoom imaging optical system of the present invention. Figure 13 This is a longitudinal aberration diagram of the intermediate focal length at infinity when focusing, as described in Embodiment 2 of the zoom imaging optical system of the present invention. Figure 14 This is a longitudinal aberration diagram of the telephoto end when focusing at infinity, as described in Embodiment 2 of the zoom imaging optical system of the present invention. Figure 15 This is a lateral aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 2 of the zoom imaging optical system of the present invention. Figure 16 This is a lateral aberration diagram of the intermediate focal length at infinity when focusing, as described in Embodiment 2 of the zoom imaging optical system of the present invention. Figure 17This is a lateral aberration diagram of the telephoto end when focusing at infinity, as described in Embodiment 2 of the zoom imaging optical system of the present invention. Figure 18 This is a lateral aberration diagram of the wide-angle end of the zoom imaging optical system of the present invention when focusing at a distance of 2.5m from the object. Figure 19 This is a lateral aberration diagram of an object at a distance of 2.5m at the intermediate focal length, as described in Embodiment 2 of the zoom imaging optical system of the present invention. Figure 20 This is a lateral aberration diagram of the telescope at a distance of 2.5m when focusing on an object at the telescope end, according to Embodiment 2 of the zoom imaging optical system of the present invention. Figure 21 This is a lens structure diagram of the wide-angle end when focusing at infinity, according to Embodiment 3 of the zoom imaging optical system of the present invention. Figure 22 This is a longitudinal aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 3 of the zoom imaging optical system of the present invention. Figure 23 This is a longitudinal aberration diagram of the intermediate focal length at infinity when focusing, as described in Embodiment 3 of the zoom imaging optical system of the present invention. Figure 24 This is a longitudinal aberration diagram of the telephoto end when focusing at infinity, as described in Embodiment 3 of the zoom imaging optical system of the present invention. Figure 25 This is a lateral aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 3 of the zoom imaging optical system of the present invention. Figure 26 This is a lateral aberration diagram of the intermediate focal length at infinity focusing, as described in Embodiment 3 of the zoom imaging optical system of the present invention. Figure 27 This is a lateral aberration diagram of the telescope at infinity focusing, as described in Embodiment 3 of the zoom imaging optical system of the present invention. Figure 28 This is a lateral aberration diagram of the wide-angle end of the zoom imaging optical system of the present invention when focusing at a distance of 2.5m from the object. Figure 29 This is a lateral aberration diagram of an object at a distance of 2.5m at the intermediate focal length, as described in Embodiment 3 of the zoom imaging optical system of the present invention. Figure 30 This is a lateral aberration diagram of the telescope at a distance of 2.5m when focusing, according to Embodiment 3 of the zoom imaging optical system of the present invention. Figure 31 This is a lens structure diagram of the wide-angle end when focusing at infinity, according to Embodiment 4 of the zoom imaging optical system of the present invention. Figure 32This is a longitudinal aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 4 of the zoom imaging optical system of the present invention. Figure 33 This is a longitudinal aberration diagram of the intermediate focal length at infinity focusing, as described in Embodiment 4 of the zoom imaging optical system of the present invention. Figure 34 This is a longitudinal aberration diagram of the telephoto end when focusing at infinity, according to Embodiment 4 of the zoom imaging optical system of the present invention. Figure 35 This is a lateral aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 4 of the zoom imaging optical system of the present invention. Figure 36 This is a lateral aberration diagram of the intermediate focal length at infinity focusing, as described in Embodiment 4 of the zoom imaging optical system of the present invention. Figure 37 This is a lateral aberration diagram of the telescope at infinity focusing, as described in Embodiment 4 of the zoom imaging optical system of the present invention. Figure 38 This is a lateral aberration diagram of the wide-angle end of the zoom imaging optical system of the present invention at a distance of 1.7m when focusing. Figure 39 This is a lateral aberration diagram of an object at a distance of 1.7m at the intermediate focal length, as described in Embodiment 4 of the zoom imaging optical system of the present invention. Figure 40 This is a lateral aberration diagram of the object at the telescope at a distance of 1.7m, as described in Embodiment 4 of the zoom imaging optical system of the present invention. Figure 41 This is a lens structure diagram of the wide-angle end when focusing at infinity, according to Embodiment 5 of the zoom imaging optical system of the present invention. Figure 42 This is a longitudinal aberration diagram of infinity focusing at the wide-angle end, as described in Embodiment 5 of the zoom imaging optical system of the present invention. Figure 43 This is a longitudinal aberration diagram of the intermediate focal length at infinity focusing, as described in Embodiment 5 of the zoom imaging optical system of the present invention. Figure 44 This is a longitudinal aberration diagram of the telephoto end when focusing at infinity, according to Embodiment 5 of the zoom imaging optical system of the present invention. Figure 45 This is a lateral aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 5 of the zoom imaging optical system of the present invention. Figure 46 This is a lateral aberration diagram of the intermediate focal length at infinity focusing, as described in Embodiment 5 of the zoom imaging optical system of the present invention. Figure 47This is a lateral aberration diagram of the telescope at infinity focusing, as described in Embodiment 5 of the zoom imaging optical system of the present invention. Figure 48 This is a lateral aberration diagram of the wide-angle end of the zoom imaging optical system of the present invention at a distance of 2.5m when focusing. Figure 49 This is a lateral aberration diagram of an object at a distance of 2.5m at the intermediate focal length, as described in Embodiment 5 of the zoom imaging optical system of the present invention. Figure 50 This is a lateral aberration diagram of the telescope at a distance of 2.5m when focusing, according to Embodiment 5 of the zoom imaging optical system of the present invention. Figure 51 This is a lens structure diagram of the wide-angle end when focusing at infinity, according to Embodiment 6 of the zoom imaging optical system of the present invention. Figure 52 This is a longitudinal aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 6 of the zoom imaging optical system of the present invention. Figure 53 This is a longitudinal aberration diagram of infinity focusing at the intermediate focal length, as described in Embodiment 6 of the zoom imaging optical system of the present invention. Figure 54 This is a longitudinal aberration diagram of the telephoto end when focusing at infinity, according to Embodiment 6 of the zoom imaging optical system of the present invention. Figure 55 This is a lateral aberration diagram of the wide-angle end at infinity focusing, as described in Embodiment 6 of the zoom imaging optical system of the present invention. Figure 56 This is a lateral aberration diagram of the intermediate focal length at infinity focusing, as described in Embodiment 6 of the zoom imaging optical system of the present invention. Figure 57 This is a lateral aberration diagram of the telescope at infinity focusing, as described in Embodiment 6 of the zoom imaging optical system of the present invention. Figure 58 This is a lateral aberration diagram of the wide-angle end of the zoom imaging optical system of the present invention at a distance of 2.5m when focusing. Figure 59 This is a lateral aberration diagram of an object at a distance of 2.5m at the intermediate focal length, as described in Embodiment 6 of the zoom imaging optical system of the present invention. Figure 60 This is a lateral aberration diagram of the object at the telescope at a distance of 3.3m, as described in Embodiment 6 of the zoom imaging optical system of the present invention. Detailed Implementation

[0016] The following describes a zoom imaging optical system according to an embodiment of the present invention. Furthermore, the following description of an example illustrates one aspect of the zoom imaging optical system according to the present invention. The present invention is not limited to this embodiment without departing from its spirit, and modifications can be made within that spirit. For example, modifications may include: making the surface formed by a sphere or plane aspherical; using a crystalline material other than optical glass or a plastic, etc., as the optical element material; using diffractive optical elements; and applying an anti-reflective coating to the lens surface, etc. The description will be conducted with the object side as the front side and the image side as the rear side.

[0017] In the description of embodiments of the present invention, when counting the number of lenses, unless otherwise specified, a single lens is counted as one lens, and in the case of a joined lens, each single lens constituting the joined lens is counted as one lens. For example, if it is a joined lens composed of a convex lens and a concave lens, it is counted as two lenses. Regarding lenses that have a shape or structure that has an aberration correction effect in resin or the like on a lens substrate such as a composite aspherical or diffractive optical element, the substrate and the attached shape or structure are considered as one unit and counted as one lens. The bonding resin layer of a joined lens is not counted as a lens. Even if the bonding resin of the joined lens has an aberration correction effect, it is considered as a structure attached to any of the joined lenses, and the resin portion is not counted as one lens. Parallel planar plates such as filters that do not have refractive power are also not counted as lenses.

[0018] Furthermore, in the description of embodiments of the present invention, a meniscus lens shape is defined as a lens whose object-side and image-side surfaces are composed of curved surfaces with radii of curvature having the same sign. For example, a concave meniscus lens with the convex surface facing the object side is a lens in which the radii of curvature of both the object-side and image-side surfaces are positive, and the radius of curvature of the image-side surface is smaller. Additionally, in the case of aspherical lenses, the lens shape is determined based on the paraxial radius of curvature.

[0019] In the description of embodiments of the present invention, a lens group is defined as a surface whose spacing on the optical axis changes due to zooming or focusing, serving as the boundary between each lens group. Therefore, when the aperture stop S moves independently due to zooming or focusing, the aperture stop S is considered as a lens group.

[0020] The refractive indices of the materials relative to the g-line (wavelength 435.8 nm), F-line (486.1 nm), d-line (587.6 nm), and C-line (656.3 nm) in the following embodiments are denoted as Ng, NF, Nd, and NC, respectively. Furthermore, the Abbe number vd, partial dispersion ratio PgF, and anomalous dispersion ΔPgF are expressed as follows: vd = (Nd-1) / (NF-NC) PgF = (Ng - NF) / (NF - NC) ΔPgF=PgF-0.64833+0.00180×vd.

[0021] In the description of the embodiments of the present invention, there are descriptions of the ray heights of the on-axis edge rays and the off-axis principal rays, but these are basically distances from the optical axis, so no positive or negative concept is generated. The optical axis is set to 0, and the direction away from the optical axis is considered positive. However, regarding the off-axis principal rays in conditions (9) and (10), a positive or negative relationship is generated because of the relationship between the imaging height of the off-axis principal rays and the height of the off-axis principal rays passing through the second lens group G2.

[0022] In super telephoto zoom lenses such as the zoom imaging optical system involved in this invention, suppressing chromatic aberration is an indispensable element for achieving high performance. There are two types of chromatic aberration: on-axis chromatic aberration and magnification chromatic aberration. To suppress both of these throughout the zoom range, the selection of appropriate glass materials corresponding to changes in optical power configuration is crucial.

[0023] Typically, the chromatic aberration of an optical system composed of thin-walled lenses is given as the sum of the individual lenses by the following (Ref. 1), and can be considered as follows. (Reference Formula 1)Σ(h·hb·φ / v) h: Height of the ray at the upper edge of the axis hb: Off-axis principal ray height φ: Refractive power v: Abbe number In addition, the on-axis edge ray is defined as the ray that passes through the aperture at the maximum height from the optical axis among the rays included in the on-axis beam, and the principal ray is defined as the ray that passes through the point where the aperture surface intersects the optical axis.

[0024] If a lens with positive refractive power is placed closer to the object than the aperture stop, the peripheral light beam passing through the lens passes through a quadrant opposite to the imaging position. In the case of ordinary optical glass, due to the characteristics of dispersion, the longer the wavelength, the lower the image height, and the C-line is observed as underdirection chromatic aberration. Similarly, if a lens with negative refractive power is placed closer to the object than the aperture stop, the opposite phenomenon occurs. Furthermore, if a lens is placed closer to the image side than the aperture stop, the peripheral light beam passing through the lens and the imaging position pass through the same quadrant, thus exhibiting the opposite phenomenon to the case where the lens is placed closer to the object than the aperture stop.

[0025] Similarly, the on-axis chromatic aberration of an optical system composed of thin-walled lenses, as the sum of the individual lenses, is given by the following (Ref. 2), and can be considered as follows. (Reference Formula 2)Σ(h·h·φ / v) h: Height of the ray at the upper edge of the axis φ: Refractive power v: Abbe number Additionally, on-axis edge rays are defined as rays that pass through the aperture at maximum height from the optical axis within the rays included in an on-axis beam.

[0026] Regarding (Ref. 2), if we consider the height of the on-axis marginal ray, then relative to the effective diameter, the higher the position of the on-axis marginal ray, the greater the amount of on-axis chromatic aberration; conversely, the lower the position of the on-axis marginal ray, the smaller the amount of on-axis chromatic aberration. Therefore, in order to suppress on-axis chromatic aberration and magnification chromatic aberration throughout the zoom range, it is necessary to appropriately select the glass material based on the changes in the ray height of the on-axis marginal ray and the off-axis principal ray generated during zooming.

[0027] In the zoom imaging optical system of the present invention, in super telephoto zoom lenses where the first lens group has positive refractive power, expands significantly when zooming from the wide-angle end to the telephoto end, and has a wide spacing with the aperture stop, in many cases, over-direction chromatic aberration occurs at the C-line on the wide-angle side, and under-direction chromatic aberration occurs on the telephoto side, varying with zoom. Therefore, when performing a summing method such as achromatic removal using the g-line and C-line, if the difference in imaging magnification with wavelengths other than these is large, as a secondary spectrum, purplish-red or other colors appear to bleed onto the outline of the subject, which is therefore undesirable.

[0028] This phenomenon arises from the following changes: when zooming from the wide-angle side to the telephoto side, the first lens group extends outward, increasing the distance between it and the aperture stop. The subsequent lens groups, through changes in optical power configuration closer to the aperture stop, exhibit significantly different correction effects for chromatic aberration, in addition to the changes in magnification chromatic aberration present in the first lens group. The greater the distance from the aperture stop, the higher the off-axis principal ray passes, as shown in (Ref. Equation 1). These changes in ray height lead to changes in chromatic aberration chromatic aberration.

[0029] Furthermore, in the correction of secondary spectra, it is effective to appropriately configure glass materials with anomalous dispersion properties based on the change in the correction effect of magnification chromatic aberration caused by zooming. For example, when decolorization is performed using the g and C lines and secondary spectra become problematic between the g and d lines, forcibly attempting decolorization using the d and C lines results in insufficient correction of the g line. However, by using glass materials with anomalous dispersion properties, the insufficient correction of the g line can be compensated for, thereby achieving a reduction in secondary spectra. Hereinafter, embodiments of the present invention that suppress secondary spectra and effectively correct magnification chromatic aberration across the entire zoom range will be described with a focus on the correction of the g line.

[0030] The zoom imaging optical system involved in this invention is configured as follows, as can be seen from the numerical embodiment or the structural diagrams of each embodiment, consisting of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM including one or more lens groups and an aperture stop S, a focusing group GF, and a subsequent group GR consisting of one lens group, arranged sequentially from the object side. The spacing between adjacent lens groups changes during zooming. When focusing from an object at infinity to a closer object, the focusing group GF moves along the optical axis.

[0031] When zooming from the wide-angle end to the telephoto end, the first lens group G1 (with positive refractive power), the second lens group G2 (with positive refractive power), and the third lens group G3 (with negative refractive power) change in the following manner: the first lens group G1 moves towards the object side, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases. This achieves the main zoom effect of the zoom imaging optical system. Furthermore, the second lens group G2 moves towards the image side when zooming from the wide-angle end to the telephoto end, thereby improving the correction effect of chromatic aberration at magnification as described below, and is therefore preferred.

[0032] When zooming from the wide-angle end to the telephoto end, the first lens group G1, which has positive refractive power, moves towards the object side. The spacing between the first lens group G1 and the second lens group G2 increases, while the spacing between the second lens group G2 and the third lens group G3 decreases. As the lens group including the aperture stop S moves towards the object side, the distance between the second lens group G2 and the aperture stop S decreases. As a result, the off-axis principal ray passing through the second lens group G2 at a high position at the wide-angle end changes to passing through a low position at the telephoto end. The magnification chromatic aberration correction effect of the second lens group G2 is greater at the wide-angle end and less at the telephoto end.

[0033] On the other hand, the first lens group G1 moves from the telephoto side to the object side, increasing the distance between it and the second lens group G2. As a result, the height of the on-axis edge ray when focusing at infinity is lower in the second lens group G2 than in the first lens group G1. In the second lens group G2, the height of the on-axis edge ray at the telephoto end is lower than the height of the off-axis principal ray at the maximum field of view at the wide-angle end.

[0034] Furthermore, in the second lens group G2, a glass material with positive anomalous dispersion is used in the concave lens and a glass material with negative anomalous dispersion is used in the convex lens, thereby enabling correction of the g-line along the under-direction on the wide-angle side and easy correction of magnification chromatic aberration.

[0035] The intermediate group GM, which includes one or more lens groups and an aperture stop S, has the effect of converging the diverging light beam in the third lens group G3, and has the effect of controlling the height of the light incident on the focusing group GF at an appropriate height. It helps to reduce the weight of the focusing group GF and also plays the role of image plane compensation during zoom.

[0036] The GF (light-field focus) moves along the optical axis when focusing from an object at infinity to a closer object, correcting for the shift in the imaging position when the distance to the object changes.

[0037] The subsequent GR group, consisting of a lens group, performs image plane compensation and corrects chromatic aberration that increases at the telephoto side. The concave lens in the subsequent GR group uses a glass material with positive anomalous dispersion, while the convex lens uses a glass material with negative anomalous dispersion. This produces a correction effect along the g-line in the overpass direction, thus correcting chromatic aberration at the telephoto side. Furthermore, in the subsequent GR group, the on-axis marginal rays pass through at a lower ray height than the off-axis principal rays. Therefore, it has the characteristic of minimizing the deterioration of on-axis chromatic aberration while the correction effect on chromatic aberration increases at higher image heights.

[0038] On the other hand, if chromatic aberration on the telephoto side is corrected by using a glass material with positive anomalous dispersion in the concave lens of the subsequent group GR and a glass material with negative anomalous dispersion in the convex lens, then the g-line on the wide-angle side becomes overcorrected on the overside, and chromatic aberration worsens. The chromatic aberration correction effect in the second lens group G2, which has a greater effect on undercorrecting the g-line along the underdirection on the wide-angle side, counteracts the worsened chromatic aberration on the wide-angle side, enabling good correction of chromatic aberration across the entire region from the wide-angle end to the telephoto end.

[0039] In the zoom imaging optical system involved in this invention, in order to effectively correct the magnification chromatic aberration generated on the telescope side, it is preferable to place one or more concave lenses that satisfy the following condition (1) between the aperture stop S and the subsequent group GR. (1) ΔPgFLnSr>0.013 ΔPgFLnSr: Anomalous dispersion of the concave lens positioned between the aperture stop S and the subsequent group GR.

[0040] In the zoom imaging optical system of this invention, light rays on the telephoto side and shorter wavelengths, especially those shorter than the g-line, are undercorrected, resulting in reduced imaging magnification and residual magnification chromatic aberration. To effectively correct this, it is preferable to use a glass material with a large ΔPgF and strong positive anomalous dispersion in the concave lens group further back than the aperture stop S. By satisfying condition (1), the magnification chromatic aberration generated on the telephoto side can be effectively corrected.

[0041] If the lower limit of condition (1) is exceeded and the aberrant dispersion of the concave lens positioned between the aperture stop S and the subsequent group GR decreases, the effect of overcorrection of the g line at the height of the peripheral image on the telephoto side will be reduced, making it difficult to perform magnification chromatic aberration correction throughout the zoom area.

[0042] In addition, regarding the lower limit value of condition (1), it is preferable to specify the lower limit value as 0.015, and more preferably as 0.020, so that the aforementioned effect can be more reliable.

[0043] In the zoom imaging optical system involved in this invention, in order to balance the reduction of the overall length of the optical system and the improvement of performance, it is preferable to include a concave lens in the first lens group G1 that satisfies the following condition (2). (2)ndLN1 < 1.80 ndLN1: The refractive index of the concave lens with the highest refractive index included in the first lens group G1.

[0044] Condition (2) specifies the refractive index of the concave lens with the highest refractive index included in the first lens group G1. In super telephoto zoom lenses with narrow field of view, such as the zoom imaging optical system according to the present invention, suppressing chromatic aberration is essential for high performance. In order to suppress chromatic aberration generated in the first lens group with positive refractive power, special low-dispersion lenses with high positive anomalous dispersion or glass materials such as fluorite are used in the convex lens, which have an achromatic effect when combined with the concave lens. However, if a high-refractive-index glass material is used in the concave lens, the Purzval and the image plane flatness will be deteriorated. By including a concave lens that satisfies condition (2) in the first lens group G1, it is possible to balance the reduction of the overall length of the optical system and the improvement of performance.

[0045] If the upper limit of condition (2) is exceeded and the refractive index of the concave lens with the highest refractive index included in the first lens group G1 becomes higher, then the purse valence deteriorates, making it difficult to ensure the flatness of the image plane, and therefore it is not preferred.

[0046] In addition, regarding condition (2), it is preferable to set the upper limit value to 1.75, and even more preferably to set it to 1.73, thereby making the aforementioned effect more reliable.

[0047] Furthermore, in the zoom imaging optical system involved in this invention, the relationship between the second lens group G2 and the lens groups before and after it, which is required to effectively correct the magnification chromatic aberration that changes when zooming from the wide-angle end to the telephoto end through the second lens group G2, is specified by conditional expressions (3) to (6).

[0048] In the zoom imaging optical system involved in this invention, in order to effectively correct the magnification chromatic aberration that changes as the zoom is made from the wide-angle end to the telephoto end through the second lens group G2, it is preferable to satisfy the following condition (3). (3)0.005<DG1G2W / DG1G2T<0.400 DG1G2W: The spacing on the optical axis between the first lens group G1 and the second lens group G2 at the infinity wide-angle end. DG1G2T: The optical axis spacing between the first lens group G1 and the second lens group G2 at the far end of the infinity telescope.

[0049] Condition (3) specifies the ratio of the spacing between the first lens group G1 and the second lens group G2 on the optical axis at both the infinity wide-angle end and the infinity telephoto end. The second lens group G2 preferably has a correction effect on chromatic aberration along the g-line in the under-direction on the wide-angle side. To improve this effect, it is preferable to have a position with a higher height of the off-axis principal ray on the wide-angle side, and a position with a lower height of the on-axis edge ray on the telephoto side, as described above. Therefore, it is preferable that the spacing between the first lens group G1 and the second lens group G2 decreases at the wide-angle end and increases at the telephoto end. By satisfying condition (3), chromatic aberration can be effectively corrected while miniaturization is achieved.

[0050] If the upper limit of condition (3) is exceeded and the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis increases at both the infinity wide-angle end and the infinity telephoto end, then the distance between the first lens group G1 and the second lens group G2 at the telephoto end decreases. Consequently, the ray height at the axial edge on the telephoto side will not be sufficiently reduced, leading to a deterioration of axial chromatic aberration, which is therefore undesirable. Furthermore, if the distance between the first lens group G1 and the second lens group G2 increases at the wide-angle end, it will affect the direction of the product's overall length extension, which is also undesirable.

[0051] If the lower limit of condition (3) is exceeded and the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis at the infinity wide-angle end and the infinity telephoto end becomes smaller, then the change of the off-axis principal ray in the second lens group G2 becomes too large when zooming from the infinity wide-angle end to the infinity telephoto end, making it difficult to correct non-point aberrations or image plane curvature, and therefore it is not preferred.

[0052] In addition, regarding condition (3), it is preferable to set the lower limit value to 0.009 and the upper limit value to 0.250, thereby making the aforementioned effect more reliable.

[0053] Furthermore, in the zoom imaging optical system involved in this invention, in order to effectively correct the magnification chromatic aberration that changes as the zoom is made from the wide-angle end to the telephoto end through the second lens group G2, it is preferable to satisfy the following conditional expression (4). (4)1.00<DG2G3W / DG2G3T<80.00 DG2G3W: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end. DG2G3T: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the far end of the infinity telescope.

[0054] Condition (4) specifies the ratio of the spacing between the second lens group G2 and the third lens group G3 on the optical axis at both the infinity wide-angle end and the infinity telephoto end. The second lens group G2 preferably has a corrective effect on chromatic aberration along the g-line in the under-direction on the wide-angle side. To improve this effect, it is preferable to have a position with a higher height of the off-axis principal ray on the wide-angle side, and a position with a lower height of the on-axis edge ray on the telephoto side, as described above. Therefore, it is preferable that the spacing between the second lens group G2 and the third lens group G3 increases at the wide-angle end and decreases at the telephoto end. By satisfying condition (4), chromatic aberration can be effectively corrected.

[0055] If the upper limit of condition (4) is exceeded and the ratio of the distance between the second lens group G2 and the third lens group G3 on the optical axis at the infinity wide-angle end and the infinity telephoto end becomes larger, then the change of the off-axis principal ray in the second lens group G2 becomes too large when zooming from the infinity wide-angle end to the infinity telephoto end, making it difficult to correct non-point aberrations or image plane curvature, and therefore it is not preferred.

[0056] If the lower limit of condition (4) is exceeded and the ratio of the distance between the second lens group G2 and the third lens group G3 on the optical axis at both the infinity wide-angle and infinity telephoto ends decreases, then the distance between the second lens group G2 and the third lens group G3 on the optical axis at the wide-angle end decreases. As a result, the off-axis principal ray height cannot pass through a position with sufficiently high height on the wide-angle side, reducing the magnification chromatic aberration correction effect towards the under-corrected g-line, which is therefore not preferred. Furthermore, if the distance between the second lens group G2 and the third lens group G3 on the optical axis increases at the telephoto end, the height of the on-axis edge ray passing through the second lens group G2 on the telephoto side will not decrease sufficiently, leading to a deterioration of on-axis chromatic aberration, which is also not preferred.

[0057] In addition, regarding condition (4), it is preferable to set the lower limit value to 2.00 and the upper limit value to 40.00, thereby making the aforementioned effect more reliable.

[0058] Furthermore, in the zoom imaging optical system of the present invention, in order to effectively correct the magnification chromatic aberration that changes when zooming from the wide-angle end to the telephoto end through the second lens group G2, it is preferable to satisfy the following conditional expression (5). (5)0.01<DG1G2W / DG2G3W<2.00 DG1G2W: The optical axis spacing between the first lens group G1 and the second lens group G2 at the infinity wide-angle end. DG2G3W: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end.

[0059] Condition (5) specifies the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis and the distance between the second lens group G2 and the third lens group G3 on the optical axis at the infinity wide-angle end. The second lens group G2 preferably has a corrective effect on chromatic aberration of the g-line along the under-direction on the wide-angle side. To improve this effect, it is preferable to have a position with a higher off-axis principal ray height on the wide-angle side and, as described above, a position with a lower on-axis edge ray height on the telephoto side. Therefore, at the infinity wide-angle end, when the second lens group G2 is closer to the first lens group G1, the distance to the first lens group G1 is shortened, and the distance to the third lens group G3 is widened, the chromatic aberration of the second lens group G2 is effectively corrected at the position where the off-axis principal ray height is high. By satisfying condition (5), the chromatic aberration of the magnification that changes as the focus shifts from the wide-angle end to the telephoto end via the second lens group G2 can be effectively corrected.

[0060] If the upper limit of condition (5) is exceeded and the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis and the distance between the second lens group G2 and the third lens group G3 on the optical axis at the infinity wide-angle end becomes larger, then at the infinity wide-angle end, the second lens group G2 will be too close to the third lens group G3. The off-axis principal ray passing through the second lens group G2 will pass through a low position, making it difficult to effectively correct the magnification chromatic aberration, and therefore it is not preferred.

[0061] If the lower limit of condition (5) is exceeded and the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis and the distance between the second lens group G2 and the third lens group G3 on the optical axis at the infinity wide-angle end becomes smaller, then the second lens group G2 will be too close to the first lens group G1 at the infinity wide-angle end. The off-axis principal ray passing through the second lens group G2 will pass through a higher position, the effective diameter of the second lens group G2 will increase, and the weight of the optical system will increase. Therefore, this is not preferred.

[0062] In addition, regarding condition (5), it is preferable to set the lower limit value to 0.03 and the upper limit value to 1.50, thereby making the aforementioned effect more reliable.

[0063] Furthermore, in the zoom imaging optical system of the present invention, in order to effectively correct the magnification chromatic aberration that changes when zooming from the wide-angle end to the telephoto end through the second lens group G2, it is preferable to satisfy the following conditional expression (6). (6)2.0<DG1G2T / DG2G3T<200.0 DG1G2T: The optical axis spacing between the first lens group G1 and the second lens group G2 at the far end of the infinity telescope. DG2G3T: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the far end of the infinity telescope.

[0064] Condition (6) specifies the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis and the distance between the second lens group G2 and the third lens group G3 on the optical axis at the infinity telescope. The second lens group G2 preferably has the effect of correcting chromatic aberration along the g-line in the under-direction on the wide-angle side. To improve its effect, it is preferable to have a position with a higher height of the off-axis principal ray on the wide-angle side and a position with a lower height of the on-axis edge ray on the telescope side, as described above. Therefore, at the infinity telescope, when the second lens group G2 is closer to the third lens group G3, the distance between it and the first lens group G1 becomes wider, and the distance between it and the third lens group G3 becomes shorter, the on-axis edge ray passes through a lower position, thus suppressing the deterioration of on-axis chromatic aberration. By satisfying condition (6), the chromatic aberration that changes as the zoom from the wide-angle end to the telescope end through the second lens group G2 can be effectively corrected.

[0065] If the upper limit of condition (6) is exceeded and the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis and the distance between the second lens group G2 and the third lens group G3 on the optical axis under the far end of infinity becomes larger, then the distance between the first lens group G1 and the second lens group G2 on the optical axis under the far end of infinity becomes too large, thereby increasing the size of the optical system, which is therefore not preferred.

[0066] If the lower limit of condition (6) is exceeded and the ratio of the distance between the first lens group G1 and the second lens group G2 on the optical axis and the distance between the second lens group G2 and the third lens group G3 on the optical axis at the far end of infinity becomes smaller, then the distance between the second lens group G2 and the third lens group G3 on the optical axis at the far end of infinity will not become smaller. The edge light rays on the axis pass through a high position, which will lead to the deterioration of the chromatic aberration on the axis, so it is not preferred.

[0067] In addition, regarding condition (6), it is preferable to set the lower limit value to 3.0 and the upper limit value to 150.0, and more preferably to set the lower limit value to 4.0 and the upper limit value to 120.0, thereby making the aforementioned effect more reliable.

[0068] Furthermore, in the zoom imaging optical system involved in this invention, in order to effectively correct magnification chromatic aberration throughout the zoom range, it is preferable to satisfy the following conditional expression (7). (7) 1.2 < DG2Sw / DG2St < 5.0 DG2Sw: The distance from the top of the lens surface closest to the object in the second lens group G2 at the wide-angle end to the aperture stop S. DG2St: The distance from the top of the surface of the lens closest to the object in the second lens group G2 at the telephoto end to the aperture stop S.

[0069] Condition (7) specifies a preferred range for the ratio of the distance from the top of the object-side surface of the lens closest to the object in the second lens group G2 at both the wide-angle and telephoto ends to the aperture stop S. As described above, when the zoom imaging optical system according to the present invention zooms from the wide-angle end to the telephoto end, the distance between the second lens group G2 and the aperture stop S included in the intermediate group GM decreases as it moves towards the image side and the interval with the third lens group G3 decreases. The magnification chromatic aberration correction effect of the second lens group G2 is preferably greater on the wide-angle side and smaller on the telephoto side. Therefore, it is preferable that the second lens group G2 is closer to the aperture stop S on the telephoto side, and the height of the off-axis principal ray passing through the second lens group G2 is lower. By satisfying condition (7), magnification chromatic aberration can be effectively corrected throughout the zoom area.

[0070] If the lower limit of condition (7) is exceeded and the ratio of the distance from the top of the object side of the lens closest to the object in the second lens group G2 to the aperture stop becomes smaller at the wide-angle end and the telephoto end, then the change caused by the magnification of the distance between the second lens group G2 and the aperture stop S becomes smaller, the change caused by the magnification of the off-axis principal ray passing through the second lens group G2 becomes smaller, and thus the change in the magnification chromatic aberration correction effect becomes smaller, making it difficult to effectively correct the magnification chromatic aberration in the entire zoom area, and therefore it is not preferred.

[0071] If the upper limit of condition (7) is exceeded and the ratio of the distance from the top of the object side of the lens closest to the object in the second lens group G2 to the aperture stop increases at the wide-angle end and the telephoto end, the change caused by the doubling of the distance between the second lens group G2 and the aperture stop S will increase. The off-axis beam at the wide-angle end will need to pass through a higher position, resulting in an increase in the outer diameter of the second lens group G2, which is therefore not preferred.

[0072] In addition, regarding condition (7), it is preferable to set the lower limit value to 1.4 and the upper limit value to 3.5, thereby making the aforementioned effect more reliable.

[0073] Furthermore, in the zoom imaging optical system involved in this invention, in order to effectively correct on-axis chromatic aberration and magnification chromatic aberration in the entire zoom area, it is preferable to satisfy the following condition (8). (8) 0.2 < g2AXhW / g2AXhT < 1.5 g2AXhW: The height of the on-axis edge ray at the infinity wide-angle end of the aperture stop on the surface in front of the second lens group G2. g2AXhT: The height of the on-axis edge ray at the far end of the infinity lens with the aperture open at the top of the telescope on the surface in front of the second lens group G2. An on-axis edge ray is defined as the ray that passes through the aperture at its maximum height from the optical axis within the rays included in an on-axis beam.

[0074] Condition (8) specifies the ratio of the height of the on-axis edge ray at the infinity wide-angle end with the aperture open to the height of the on-axis edge ray at the infinity telephoto end with the aperture open on the surface of the second lens group G2. In the second lens group G2, as described above, in order to correct the g-line along the under-direction on the wide-angle side and suppress chromatic aberration, it is preferable to use a glass material with positive anomalous dispersion in the concave lens. On the other hand, if a glass material with a large ΔPgF and strong positive anomalous dispersion is used in the concave lens of the second lens group G2, the imaging position of the g-line or C-line in the on-axis beam will shift towards the image side, thus acting in the direction of increased secondary spectrum, which is not conducive to correcting on-axis chromatic aberration. Moreover, the narrower the field of view on the telephoto side, the more easily on-axis chromatic aberration becomes obvious, so in order to achieve high image quality, it is also necessary to suppress the deterioration of on-axis chromatic aberration. Therefore, in order to prevent the deterioration of on-axis chromatic aberration while using lens materials with strong positive anomalous dispersion that are beneficial for correcting chromatic aberration on the wide-angle side, it is necessary to control the height of the on-axis edge rays to be smaller than the effective diameter of the second lens group G2 (in the case of the second lens group G2, the effective diameter is determined by the height of the off-axis beam at the maximum field of view at the wide-angle end), especially on the telephoto side. By satisfying condition (8), on-axis chromatic aberration and chromatic aberration on the zoom range can be effectively corrected.

[0075] If the upper limit of condition (8) is exceeded and the ratio of the height of the on-axis edge ray under the infinity wide-angle end of the aperture opening to the height of the on-axis edge ray under the infinity telephoto end of the aperture opening on the surface in front of the second lens group G2 becomes larger, then the height of the on-axis edge ray under the infinity wide-angle end of the aperture opening on the surface in front of the second lens group G2 becomes too large, making it difficult to correct the on-axis chromatic aberration on the wide-angle side. Furthermore, in order to reduce the height of the on-axis edge ray on the telephoto side, it is necessary to strengthen the refractive power of the first lens group G1, leading to the deterioration of various aberrations and making it difficult to achieve high performance.

[0076] If the lower limit of condition (8) is exceeded and the ratio of the height of the on-axis edge ray under the infinity wide-angle end of the aperture opening to the height of the on-axis edge ray under the infinity telephoto end of the aperture opening on the surface in front of the second lens group G2 becomes smaller, then the height of the on-axis edge ray under the infinity telephoto end of the aperture opening on the surface in front of the second lens group G2 becomes larger, making it difficult to correct on-axis chromatic aberration and difficult to achieve high performance.

[0077] In addition, regarding condition (8), it is preferable to set the lower limit value to 0.3 and the upper limit value to 1.3, and even more preferably to set the lower limit value to 0.4 and the upper limit value to 1.1, thereby making the aforementioned effect more reliable.

[0078] Furthermore, in the zoom imaging optical system involved in this invention, the second lens group G2, whose ray height changes greatly when zooming from the wide-angle end to the telephoto end, plays an important role in effectively correcting the magnification chromatic aberration that changes due to zooming. In order to improve the performance of the optical system, it is preferable to satisfy the following conditions (9) and (10). (9)-1.8<(g2OAhW / Wih)-(g2OAhT / Tih)<-0.3 (10)0.6<|g2OAhW / g2AXhT|<2.5 Wih: Image height of the off-axis principal ray at the maximum field of view at infinity. Tih: Image height of the off-axis principal ray at the maximum field of view of the telescope at infinity. g2OAhW: The height of the off-axis principal ray at the maximum field of view at infinity on the plane in front of the second lens group G2. g2OAhT: The height of the off-axis principal ray at the maximum field of view at the far end of the infinity telescope on the plane in front of the second lens group G2. g2AXhT: The height of the on-axis edge ray at the far end of the infinity lens with the aperture open at the top of the telescope on the surface in front of the second lens group G2. Furthermore, the ray of g2OAhW corresponds to Wih, and the ray of g2OAhT corresponds to Tih. The second lens group G2 is located closer to the object than the aperture stop S, and the quadrants through which the light rays pass are reversed. Therefore, g2OAhW and g2OAhT have different symbols relative to Wih and Tih. Also, an on-axis edge ray is defined as the ray included in the on-axis beam that passes through the aperture stop at its maximum height from the optical axis.

[0079] Condition (9) specifies a preferred range for the ratio of the height of the off-axis principal ray at the maximum field of view at infinity on the surface in front of the second lens group G2 to the image height of the off-axis principal ray at the same wide-angle end, and the difference between the height of the off-axis principal ray at the maximum field of view at infinity on the surface in front of the second lens group G2 and the image height of the off-axis principal ray at the same telephoto end. If this difference is close to 0 and increases, it means that the change in the off-axis principal ray in the second lens group G2 is small when zooming from the infinity wide-angle end to the infinity telephoto end. Conversely, if it decreases in a direction away from 0, it means that the change in the off-axis principal ray in the second lens group G2 is large when zooming from the infinity wide-angle end to the infinity telephoto end. By satisfying condition (9), magnification chromatic aberration caused by zooming can be effectively corrected.

[0080] If the upper limit of condition (9) is exceeded and the difference between the ratio of the height of the off-axis principal ray of the maximum field of view at infinity on the surface in front of the second lens group G2 to the image height of the off-axis principal ray of the maximum field of view at the same wide-angle end and the ratio of the height of the off-axis principal ray of the maximum field of view at infinity on the surface in front of the second lens group G2 to the image height of the off-axis principal ray of the maximum field of view at the same telephoto end is close to 0, then the change of the off-axis principal ray in the second lens group G2 when zooming from the infinity wide-angle end to the infinity telephoto end becomes smaller, the correction effect of magnification chromatic aberration becomes smaller, and the magnification chromatic aberration cannot be fully corrected on either the wide-angle side or the telephoto side, so it is not preferred.

[0081] If the lower limit of condition (9) is exceeded and the difference between the height of the off-axis principal ray of the maximum field of view at the infinity wide-angle end on the surface in front of the second lens group G2 and the image height of the off-axis principal ray of the maximum field of view at the same wide-angle end, and the difference between the height of the off-axis principal ray of the maximum field of view at the infinity telephoto end on the surface in front of the second lens group G2 and the image height of the off-axis principal ray of the maximum field of view at the same telephoto end, decreases in the direction away from 0, then when zooming from the infinity wide-angle end to the infinity telephoto end, the change of the off-axis principal ray in the second lens group G2 becomes too large, making it difficult to correct non-point aberrations or image plane curvature, and therefore is not preferred.

[0082] In addition, regarding condition (9), it is preferable to set the lower limit value to -1.5 and the upper limit value to -0.4, thereby making the aforementioned effect more reliable.

[0083] Condition (10) specifies the absolute value of the ratio of the height of the off-axis principal ray at the maximum field of view at infinity on the surface in front of the second lens group G2 to the height of the upper-axis edge ray at the infinity telephoto end with the aperture open on the surface in front of the second lens group G2. Furthermore, the off-axis principal ray specified in condition (10) refers to the off-axis principal ray at the maximum field of view at infinity as specified in condition (9). By satisfying condition (10), magnification chromatic aberration caused by zoom can be effectively corrected.

[0084] If the upper limit of condition (10) is exceeded and the absolute value of the ratio of the height of the off-axis principal ray at the maximum field of view at the infinity wide-angle end to the height of the on-axis edge ray at the infinity telephoto end with the aperture open on the surface in front of the second lens group G2 becomes larger, then in order to reduce the height of the on-axis edge ray on the telephoto side, the refractive power of the first lens group G1 needs to be strengthened, which leads to the deterioration of various aberrations and makes it difficult to achieve high performance.

[0085] If the lower limit of conditional equation (10) is exceeded and the absolute value of the ratio of the height of the off-axis principal ray at the maximum field of view at infinity on the surface in front of the second lens group G2 to the height of the on-axis edge ray at the infinity telephoto end with the aperture open on the surface in front of the second lens group G2 becomes smaller, then the height of the on-axis edge ray on the telephoto side will not decrease sufficiently, resulting in increased on-axis chromatic aberration in the second lens group G2, making it difficult to achieve high performance. Furthermore, the decrease in the absolute value of the height of the off-axis principal ray at the maximum field of view at infinity (which is synonymous with simply reducing the height of the off-axis principal ray from the optical axis without considering the concept of sign) makes it difficult to correct magnification chromatic aberration on the wide-angle side, making it difficult to achieve high performance.

[0086] In addition, regarding condition (10), it is preferable to set the lower limit value to 0.8 and the upper limit value to 1.9, thereby making the aforementioned effect more reliable.

[0087] Furthermore, in the zoom imaging optical system of the present invention, the second lens group G2, in which the height of the off-axis principal ray changes significantly when zooming from the wide-angle end to the telephoto end, plays an important role in effectively correcting the magnification chromatic aberration that changes due to zooming, and preferably includes at least one concave lens.

[0088] To effectively correct chromatic aberration on the wide-angle side, it is important that the second lens group G2 uses a glass material that has the effect of correcting the g-line along the under-direction on the wide-angle side. In the case of a convex lens, a glass material with negative anomalous dispersion is preferred; in the case of a concave lens, a glass material with positive anomalous dispersion is preferred. As for glass materials with negative anomalous dispersion, if they are from HOYA Corporation, high-refractive-index, low-dispersion glass materials such as TAFD30 or high-lead glass materials such as LAF45 are suitable. As for glass materials with positive anomalous dispersion, if they are from HOYA Corporation, low-refractive-index, low-dispersion glass materials such as FCD1, high-refractive-index, high-dispersion glass materials such as E-FDS1-W, and high-dispersion glass materials such as FD270 are suitable. Comparing the two, glass materials with positive anomalous dispersion exhibit greater anomalous dispersion due to the wide variety of glass types and the high degree of freedom in material selection. Therefore, it is preferable to include at least one concave lens in the second lens group G2, and preferably, this concave lens should be made of a glass material with high positive anomalous dispersion. By including at least one concave lens in the second lens group G2, chromatic aberration caused by zooming can be effectively corrected.

[0089] Furthermore, in the zoom imaging optical system of the present invention, the second lens group G2, in which the height of the off-axis principal ray changes greatly when zooming from the wide-angle end to the telephoto end, plays an important role in effectively correcting the magnification chromatic aberration that changes due to zooming. Therefore, it is preferable to include at least one concave lens that satisfies the following condition (11). (11) ΔPgFLg2>0.0090 ΔPgFLg2: The anomalous dispersion of the concave lens with the greatest anomalous dispersion among the concave lenses included in the second lens group G2.

[0090] Condition (11) specifies the preferred range of anomalous dispersion for a second lens group G2 that includes more than one concave lens. Furthermore, the concave lens shown here can be a standalone lens or a concave lens configured as part of a combined lens.

[0091] As described above, when zooming from the wide-angle end to the telephoto end, the second lens group G2 moves relative to the image plane towards the image side. The off-axis principal ray passing through the second lens group G2 passes through a high position on the wide-angle side and a low position on the telephoto side. In order to suppress chromatic aberration and achieve high performance throughout the zoom range, the second lens group G2 needs to further correct the g-line in the under-range on the wide-angle side. Therefore, a large and positive ΔPgF indicates strong anomalous dispersion, which is beneficial for the correction of the g-line. By satisfying condition (11), the chromatic aberration that changes due to zoom can be effectively corrected.

[0092] If the lower limit of condition (11) is exceeded and the anomalous dispersion of the concave lens with the largest anomalous dispersion among the concave lenses included in the second lens group G2 decreases, the effect of correcting the g line to be insufficient on the wide-angle side is reduced, making it difficult to suppress magnification chromatic aberration and achieve high performance throughout the zoom range.

[0093] In addition, regarding condition (11), it is preferable to set the lower limit value to 0.0095, more preferably to 0.0100, and even more preferably to 0.0150, thereby making the aforementioned effect more reliable.

[0094] Furthermore, in the zoom imaging optical system of the present invention, it is preferable to include at least one concave lens satisfying the following condition (12) in the subsequent group GR. In addition, the concave lens shown here may be a lens configured separately or a concave lens configured as part of a bonding lens. (12) ΔPgFnLr>0.009 ΔPgFnLr: Anomalous dispersion of the concave lens in the subsequent GR group

[0095] Condition (12) specifies that the anomalous dispersion of the subsequent group GR of the zoom imaging optical system according to the present invention preferably includes one or more concave lenses. In the zoom imaging optical system according to the present invention, light rays on the telephoto side and shorter wavelengths, especially those shorter than the g-line, are undercorrected, resulting in reduced magnification and residual magnification chromatic aberration in the wrong direction. To effectively correct this, in the group further back than the aperture stop S, a glass material with a large ΔPgF and strong positive anomalous dispersion is preferably used in the concave lenses. By satisfying condition (12), magnification chromatic aberration throughout the zoom range can be effectively corrected.

[0096] If the lower limit of condition (12) is exceeded and the aberrant dispersion of the concave lens constituting the subsequent group GR decreases, the effect of overcorrecting the g line at the height of the peripheral image on the telephoto side will be reduced, making it difficult to correct the magnification chromatic aberration throughout the zoom area.

[0097] In addition, regarding the lower limit value of condition (12), it is preferable to set the lower limit value to 0.010, more preferably 0.011, and even more preferably 0.013, thereby making the aforementioned effect more reliable.

[0098] Furthermore, in the zoom imaging optical system of the present invention, it is preferable to include at least one concave lens satisfying the following condition (13) in the subsequent group GR. In addition, the concave lens shown here may be a lens configured separately or a concave lens configured as part of a bonding lens. (13) vdnLr×ΔPgFnLr>0.80 vdnLr: Abbe number of the concave lenses included in the subsequent group GR. ΔPgFnLr: Anomalous dispersion of the concave lenses included in the subsequent group GR

[0099] Condition (13) specifies the relationship between the Abbe number and anomalous dispersion of the subsequent group GR of the zoom imaging optical system according to the present invention, which preferably includes one or more concave lenses. In the zoom imaging optical system according to the present invention, light rays on the telephoto side and short wavelengths, especially those shorter than the g line, are undercorrected, resulting in reduced imaging magnification and residual magnification chromatic aberration. To effectively correct this, in the group further back than the aperture stop S, it is preferable to use a glass material with a large ΔPgF and a large positive anomalous dispersion in the concave lenses. Furthermore, the glass materials that satisfy condition (12) are generally low-refractive-index glass materials with a refractive index of about 1.7 or less, which not only have anomalous dispersion that is preferred for correcting magnification chromatic aberration, but also, due to their low refractive index, are beneficial for correcting Pötzvar and variability. By satisfying condition (13), magnification chromatic aberration can be effectively corrected throughout the zoom range.

[0100] If the aberrant dispersion of at least one concave lens in the subsequent group GR exceeds the lower limit of condition (13), the effect of overcorrection of the g-line at the height of the peripheral image on the telephoto side will be reduced, making it difficult to correct magnification chromatic aberration throughout the zoom area.

[0101] In addition, regarding the lower limit value of condition (13), it is preferable to set the lower limit value to 0.85, and even more preferably to set the lower limit value to 0.90, thereby making the aforementioned effect more reliable.

[0102] Furthermore, in the zoom imaging optical system of the present invention, it is preferable to include at least one convex lens satisfying the following condition (14) in the subsequent group GR. In addition, the convex lens shown here may be a lens configured separately or a convex lens configured as part of a combined lens. (14)ΔPgFpLr<-0.0010 ΔPgFpLr: Anomalous dispersion of the convex lens included in the subsequent group GR

[0103] Condition (14) specifies that the subsequent group GR of the zoom imaging optical system involved in this invention includes at least one convex lens with anomalous dispersion. In the zoom imaging optical system involved in this invention, the imaging magnification of light rays on the telephoto side and short wavelengths, especially from the g line to the short wavelength side, is reduced, resulting in residual magnification chromatic aberration in the under-direction. To effectively correct this, in the group further back than the aperture stop S, a glass material with a small ΔPgF and strong negative anomalous dispersion is preferably used in the convex lens. By satisfying condition (14), magnification chromatic aberration can be effectively corrected throughout the zoom range.

[0104] If the aberrant dispersion of the convex lens exceeds the upper limit of condition (14) and is greater than that of at least one convex lens in the subsequent group GR, the effect of overcorrection of the g line on the telephoto side is reduced, making it difficult to suppress magnification chromatic aberration throughout the zoom area.

[0105] In addition, regarding condition (14), it is preferable to specify the upper limit value as -0.0020, more preferably as -0.0030, and even more preferably as -0.0040, thereby making the aforementioned effect more reliable.

[0106] Furthermore, in the zoom imaging optical system of the present invention, it is preferable that the average value of the anomalous dispersion of the two convex lenses, measured from the image side closest to the image, satisfies the range of conditional expression (15). Additionally, the convex lens shown here can be a separately configured lens or a convex lens configured as part of a combined lens. (15)ΔPgFprAVE<-0.0010 ΔPgFprAVE: The average value of the anomalous dispersion of the two convex lenses closest to the image side.

[0107] Condition (15) specifies the average anomalous dispersion of the two convex lenses in the zoom imaging optical system of the present invention, taken from the image side. In the zoom imaging optical system of the present invention, the magnification of light rays from the telephoto side and shorter wavelengths, especially from the g-line to the shorter wavelength side, decreases, resulting in residual magnification chromatic aberration. To effectively correct this, in the group further back than the aperture stop S, a glass material with a small ΔPgF and strong negative anomalous dispersion is preferably used in the convex lenses. Furthermore, the closer the lens is to the image side, the higher the position of off-axis rays, thus resulting in a higher correction effect for magnification chromatic aberration.

[0108] If the upper limit of condition (15) is exceeded and the average value of the abnormal dispersion of the two convex lenses on the image side increases, the effect of overcorrecting the g-line on the telephoto side will be reduced, making it difficult to suppress magnification chromatic aberration throughout the zoom range.

[0109] In addition, regarding condition (15), it is preferable to specify the upper limit value as -0.0020, more preferably as -0.0030, and even more preferably as -0.0040, thereby making the aforementioned effect more reliable.

[0110] Furthermore, in the zoom imaging optical system involved in this invention, in order to balance the reduction of the overall length of the optical system and the improvement of performance, the following condition (16) is preferably satisfied. (16) 0.18 < f1 / fT < 1.00 f1: Focal length of the first lens group G1 fT: Focal length of the zoom imaging optical system at the far end of an infinity telescope.

[0111] Condition (16) specifies the ratio of the focal length of the first lens group G1 to the focal length of the zoom imaging optical system at the infinity telescope, showing an optimal range in terms of reducing the overall length of the optical system and reducing the weight of the lens barrel. By satisfying condition (16), it is possible to balance the reduction of the overall optical length and the improvement of performance.

[0112] If the upper limit of condition (16) is exceeded and the focal length of the first lens group G1 becomes longer relative to the focal length of the zoom imaging optical system at the infinity telescope end, then the total optical length at the telescope end becomes too long, the amount of movement of the first lens group G1 caused by zoom increases, the moving mechanism becomes more complex, and the lens barrel becomes larger.

[0113] If the lower limit of condition (16) is exceeded and the focal length of the first lens group G1 becomes shorter relative to the focal length of the zoom imaging optical system at the infinity telescope, then the imaging magnification of the composite system after the second lens group G2 at the telescope becomes too high, making it difficult to correct various aberrations such as on-axis chromatic aberration at the telescope.

[0114] In addition, regarding condition (16), it is preferable to set the lower limit value to 0.20 and the upper limit value to 0.85, and even more preferably to set the lower limit value to 0.24 and the upper limit value to 0.70, thereby making the aforementioned effect more reliable.

[0115] Furthermore, in the zoom imaging optical system involved in this invention, in order to balance the reduction of the overall length of the optical system and the improvement of performance, it is preferable to satisfy the following condition (17). (17) 0.1 < f2 / fT < 1.4 f2: Focal length of the second lens group G2 fT: Focal length of the zoom imaging optical system at the far end of an infinity telescope.

[0116] Condition (17) specifies the ratio of the focal length of the second lens group G2 to the focal length of the zoom imaging optical system at the infinity telescope, showing a preferred range in terms of reducing the overall length of the optical system and lightening the lens barrel. By satisfying condition (17), it is possible to reduce the overall optical length and lighten the lens barrel.

[0117] If the upper limit of conditional equation (17) is exceeded and the focal length of the second lens group G2 becomes longer relative to the focal length of the zoom imaging optical system at the infinity telescope, the combined positive refractive power of the first lens group G1 and the second lens group G2 becomes smaller, making it difficult to shorten the overall length of the optical system. Furthermore, if the insufficient combined refractive power of the first lens group G1 and the second lens group G2 is used to enhance and compensate for the refractive power of the first lens group G1, it will be difficult to use low refractive index / low dispersion glass such as fluorite in the convex lens of the first lens group G1, which plays an important role in the correction of on-axis chromatic aberration, making it difficult to achieve high performance.

[0118] If the lower limit of condition (17) is exceeded and the focal length of the second lens group G2 becomes smaller relative to the focal length of the zoom imaging optical system at the far end of the infinity telescope, then the refractive power of the second lens group G2 becomes stronger, especially when the off-axis principal ray passes through the wide-angle end at a high position, it is difficult to suppress non-point aberrations and achieve high performance.

[0119] In addition, regarding condition (17), it is preferable to set the lower limit value to 0.20 and the upper limit value to 1.10, thereby making the aforementioned effect more reliable.

[0120] Furthermore, in the zoom imaging optical system involved in this invention, in order to balance the reduction of the overall length of the optical system and the improvement of performance, the following condition (18) is preferably satisfied. (18) 0.6 < f1 / f2 < 2.2 f1: Focal length of the first lens group G1 f2: Focal length of the first lens group G2

[0121] Condition (18) represents the preferred range of the focal length ratio of the first lens group G1 and the second lens group G2. By satisfying condition (18), both the reduction of the total optical length and the improvement of performance can be achieved.

[0122] If the upper limit of condition (18) is exceeded and the ratio of the focal length of the first lens group G1 to the second lens group G2 becomes larger, it means that the refractive power of the first lens group G1 becomes smaller than that of the second lens group G2. The insufficient refractive power of the first lens group G1 leads to the increase in the size of the optical system, which is not preferred.

[0123] If the lower limit of condition (18) is exceeded and the ratio of the focal lengths of the first lens group G1 to the second lens group G2 becomes smaller, it means that the refractive power of the first lens group G1 relative to the second lens group G2 becomes greater, and the imaging magnification of the synthesis system after the second lens group G2 at the telephoto end becomes too high, making it difficult to correct various aberrations such as on-axis chromatic aberration at the telephoto end.

[0124] In addition, regarding condition (18), it is preferable to set the lower limit value to 0.7 and the upper limit value to 1.8, thereby making the aforementioned effect more reliable.

[0125] Furthermore, in the zoom imaging optical system involved in this invention, in order to balance the reduction of the overall length of the optical system and the improvement of performance, the following condition (19) is preferably satisfied. (19) 1.0 < f1 / fW < 5.0 f1: Focal length of the first lens group G1 fW: Focal length of the zoom imaging optical system at infinity wide-angle end

[0126] Condition (19) specifies the ratio of the focal length of the zoom imaging optical system at the infinity wide-angle end to the focal length of the first lens group G1, and shows an optimal range in order to balance the reduction of the overall length of the optical system and the improvement of performance. By satisfying condition (19), it is possible to balance the reduction of the overall optical length and the improvement of performance.

[0127] If the upper limit of condition (19) is exceeded and the focal length of the first lens group G1 becomes larger than the focal length of the zoom imaging optical system at the infinity wide-angle end, then the refractive power of the first lens group G1 is insufficient and it is difficult to shorten the total length of the optical system, so it is not preferred.

[0128] If the lower limit of condition (19) is exceeded and the focal length of the first lens group G1 becomes smaller relative to the focal length of the zoom imaging optical system at the infinity wide-angle end, the refractive power of the first lens group G1 becomes too strong and it is difficult to correct various aberrations such as spherical aberration or non-point aberration, making it difficult to improve performance. Therefore, it is not preferred.

[0129] In addition, regarding condition (19), it is preferable to set the lower limit to 1.3 and the upper limit to 4.0, thereby making the aforementioned effect more reliable.

[0130] Furthermore, in the zoom imaging optical system involved in this invention, in order to balance the reduction of the overall length of the optical system and the improvement of performance, it is preferable to satisfy the following condition (20). (20) 0.5 < f2 / fW < 8.5 f2: Focal length of the second lens group G2 fW: Focal length of the zoom imaging optical system at infinity wide-angle end

[0131] Condition (20) specifies the ratio of the focal length of the zoom imaging optical system at the infinity wide-angle end to the focal length of the second lens group G2, and shows an optimal range in order to balance the reduction of the overall length of the optical system and the improvement of performance. By satisfying condition (20), it is possible to balance the reduction of the overall optical length and the improvement of performance.

[0132] If the upper limit of conditional expression (20) is exceeded and the focal length of the second lens group G1 becomes larger than the focal length of the zoom imaging optical system at the infinity wide-angle end, the refractive power of the second lens group G2 is insufficient and it is difficult to shorten the total length of the optical system. At the same time, it is necessary to compensate for the insufficient refractive power by strengthening the refractive power of the first lens group G1. As a result, the aberration generated in the first lens group G1 increases, making it difficult to improve performance. Therefore, it is not preferred.

[0133] If the lower limit of condition (20) is exceeded and the focal length of the second lens group G2 becomes smaller relative to the focal length of the zoom imaging optical system at the infinity wide-angle end, the refractive power of the second lens group G2 becomes too strong, and the coma and non-point aberrations generated in the second lens group become larger, making it difficult to achieve high performance, and therefore it is not preferred.

[0134] In addition, regarding condition (20), it is preferable to set the lower limit to 0.7 and the upper limit to 7.5, thereby making the aforementioned effect more reliable.

[0135] Furthermore, in the zoom imaging optical system involved in this invention, the following condition (21) is preferably satisfied. (21) 0.04 < |fF / fT| < 0.35 fF: Focal length of the focus group GF fT: Focal length of the zoom imaging optical system at the far end of an infinity telescope.

[0136] A shorter movement distance of the focusing group GF from infinity to the near side has the advantage of increasing focusing speed, but it requires increasing the refractive power of the focusing group GF, resulting in a greater decrease in focusing performance, which is therefore not preferred. Based on this, condition (21) specifies an optimal range for the absolute value of the ratio of the focal length of the focusing group GF to the focal length of the zoom imaging optical system at infinity telephoto end in order to suppress the increase in focusing speed and the decrease in focusing performance. By satisfying condition (21), it is possible to effectively correct various aberrations while achieving a high focusing speed.

[0137] If the lower limit of condition (21) is exceeded and the absolute value of the ratio of the focal length of the focusing group GF to the focal length of the zoom imaging optical system at the infinity telephoto end becomes smaller, then the refractive power of the focusing group GF becomes too strong, and the performance change caused by the deterioration of various aberrations during focusing becomes too large, so it is not preferred.

[0138] If the upper limit of condition (21) is exceeded and the absolute value of the ratio of the focal length of the focusing group GF to the focal length of the zoom imaging optical system at the infinity telephoto end becomes larger, then the refractive power of the focusing group GF is insufficient, resulting in a greater amount of movement of the focusing group GF from infinity to the near end, which leads to a decrease in focusing speed, and therefore is not preferred.

[0139] In addition, regarding condition (21), it is preferable to set the lower limit to 0.06 and the upper limit to 0.20, thereby making the aforementioned effect more reliable.

[0140] Furthermore, in the zoom imaging optical system involved in this invention, the following condition (22) is preferably satisfied. (22)2.0<|{1-(βFT)^2}×(βRT)^2|<20.0 βFT: Horizontal magnification at infinity telephoto end of the GF focus group. βRT: Lateral magnification at infinity for all lens groups positioned closer to the image side than the focusing group GF.

[0141] Condition (22) specifies the absolute value of the focusing sensitivity of the focusing group GF. The focusing sensitivity is the ratio (ΔL / Δd) of the amount of movement Δd of the focusing group GF in the optical axis direction to the amount of movement ΔL of the imaging position in the optical axis direction caused by the movement of the focusing group GF. The larger the absolute value of the focusing sensitivity, the more the imaging point can be moved along the optical axis direction with a small amount of movement of the focusing group. By satisfying condition (22), various aberrations can be effectively corrected while achieving high-speed focusing.

[0142] If the lower limit of condition (22) is exceeded and the absolute value of the focusing sensitivity of the focus group GF decreases, the amount of movement of the focus group GF during focusing will increase, resulting in a decrease in focusing speed, which is therefore not preferred.

[0143] If the upper limit of condition (22) is exceeded and the absolute value of the focusing sensitivity of the focusing group GF increases, the refractive power of the focusing group GF becomes too strong, and the performance change caused by the deterioration of various aberrations during focusing becomes too large, so it is not preferred.

[0144] In addition, regarding condition (22), it is preferable to set the lower limit to 2.5 and the upper limit to 15.0, and even more preferably to set the lower limit to 3.0 and the upper limit to 12.5, thereby making the aforementioned effect more reliable.

[0145] Furthermore, in the zoom imaging optical system according to the present invention, the mechanism is prevented from becoming complicated by fixing the third lens group G3 relative to the image plane during zooming. This is because, when a portion of the third lens group G3 is moved in a substantially vertical direction relative to the optical axis and serves as a vibration damping group, the drive unit or wiring will not move due to zooming, thus simplifying the mechanism and is preferable. Additionally, the position of the vibration damping group is not necessarily limited to a portion of the third lens group G3. For example, a portion of the lens group closer to the image side than the aperture stop can also be moved in a substantially vertical direction and served as a vibration damping group.

[0146] Furthermore, in the zoom imaging optical system of the present invention, in order to prevent the mechanical mechanism from becoming complicated, it is preferable that the lens group closest to the image side in the subsequent group GR is fixed relative to the image plane during zooming.

[0147] Next, the lens structure of an embodiment of the imaging optical system of the present invention will be described, and specific numerical data will be shown. Furthermore, in the following description, the lens structure will be described in order from the object side to the image side.

[0148] In the [Surface Data], the surface number is the number of the lens surface or aperture stop S measured from the object side; r is the radius of curvature of each lens surface; d is the interval between each lens surface; nd is the refractive index relative to the d-line (wavelength 587.56 nm); vd is the Abbe number relative to the d-line; and ΔPgF is a value calculated using the formula PgF - 0.64833 + 0.00180 × vd. Furthermore, the corresponding glass materials, as examples of glasses corresponding to the refractive index, Abbe number, and ΔPgF recorded in the [Surface Data], include the glass material names of HOYACorporation, OHARA Inc., and HIKARI GLASS Co., Ltd.

[0149] The asterisk (*) next to the surface number indicates that the lens surface is aspherical. Furthermore, BF represents the back focal length, and the object distance indicates the distance from the subject to the first surface of the lens.

[0150] The (aperture stop) attached to the surface number indicates that the aperture stop S is located at that position. The radius of curvature relative to the plane or the aperture stop S is marked with ∞ (infinity).

[0151] In the [Aspherical Data] section, the values ​​of the coefficients for the aspherical shape assigned to the lens surface marked with an asterisk (*) in the [Surface Data] section are shown. The aspherical shape is represented by the following formula. In the following formula, y represents the displacement from the optical axis in the direction orthogonal to the optical axis, z represents the displacement (vertical measure) from the intersection of the optical axis and the aspherical surface towards the optical axis, r represents the radius of curvature of the reference sphere, and K represents the conic coefficient. Furthermore, A4, A6, A8, and A10 represent the aspherical coefficients of orders 4, 6, 8, and 10, respectively.

[0152] The [Various Data] section shows the zoom ratio and focal length at various shooting distances.

[0153] The [Variable Interval Data] section shows the variable interval and BF values ​​for each shooting distance focusing state.

[0154] The [Lens Group Data] section shows the object-side surface number that makes up each lens group and the combined focal length of the entire group.

[0155] Furthermore, in the aberration diagrams corresponding to each embodiment, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image plane and the meridional image plane, respectively.

[0156] In addition, in all the following specifications, unless otherwise stated, the focal length f, radius of curvature r, lens surface spacing d, and other lengths are in millimeters (mm), but the same optical performance can be obtained even in proportional magnification and proportional reduction in optical systems, and therefore are not limited thereto.

[0157] Furthermore, as lens names, the lens positioned closest to the object is called L1, the second lens positioned facing the image is called L2, and the third lens is called L3.

[0158] Furthermore, in the lens structure diagrams of each embodiment, I represents the image plane, F represents the filter, and the single-dot dashed line passing through the center represents the optical axis.

[0159] [Example 1] Figure 1 This is a diagram of the lens structure of the zoom imaging optical system described in Example 1 when focusing at infinity at the wide-angle end.

[0160] Figure 1The zoom imaging optical system consists of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM composed of a fourth lens group G4, a focusing group GF composed of a fifth lens group G5 that moves along the optical axis when focusing from an object at infinity to a closer object, and a subsequent group GR composed of a sixth lens group G6, arranged sequentially from the object side.

[0161] The first lens group G1 consists of a combined lens of a concave meniscus lens L1 (convex side facing the object) and a biconvex lens L2, and a convex meniscus lens L3 (convex side facing the object). The second lens group G2 consists of a combined lens of a biconvex lens L4 and a concave meniscus lens L5 (convex side facing the image). The third lens group G3 consists of a combined lens of a biconcave lens L6 and a convex meniscus lens L7 (convex side facing the object), a concave meniscus lens L8 (convex side facing the object), and a combined lens of a biconcave lens L9 and a biconvex lens L10. Furthermore, the third lens group G3 can function as a vibration damping group by moving L8 to L10 integrally relative to the optical axis in a substantially perpendicular direction; however, lenses other than L8 to L10 can also be used as vibration damping groups. Lens group G4 consists of a combined lens of biconvex lens L11, biconvex lens L12, and biconcave lens L13; a combined lens of biconvex lens L14, biconcave lens L15, and biconvex lens L16; and an aperture stop S. Lens group G5 consists of a combined lens of biconvex lens L17 and a concave meniscus lens L18 with its convex surface facing the image side. Lens group G6 consists of a combined lens of convex meniscus lens L19 with its convex surface facing the image side; biconcave lens L20; biconvex lens L21 and biconcave lens L22; a combined lens of convex meniscus lens L23 with its convex surface facing the image side and a concave meniscus lens L24 with its convex surface facing the image side; and a concave meniscus lens L25 with its convex surface facing the image side.

[0162] When zooming from the wide-angle end to the telephoto end, the third lens group G3 and the sixth lens group G6 are fixed relative to the image plane. The first lens group G1 moves towards the object side, the second lens group G2 moves towards the image side, the fourth lens group G4 moves towards the object side, and the fifth lens group G5 moves towards the image side after moving towards 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, and the distance between the fifth lens group G5 and the sixth lens group G6 decreases after increasing and becomes smaller relative to the wide-angle end at the telephoto end. When focusing from an object at infinity to a closer object, the fifth lens group G5 moves towards the object side.

[0163] L18 becomes a concave lens that satisfies condition (1). L1 becomes a concave lens that satisfies condition (2). L5 becomes a concave lens that satisfies condition (11). L22 and L24 become concave lenses that satisfy condition (12). L22 and L24 become concave lenses that satisfy condition (13). L21 and L23 become convex lenses that satisfy condition (14). L21 and L23 become convex lenses that satisfy condition (15).

[0164] The following shows the specifications of the zoom imaging optical system involved in Example 1.

[0165] Numerical Example 1 Unit: mm [Surface Data] [Various data] [Variable Interval Data] When focusing at infinity When focusing on close objects [Lens Group Data]

[0166] [Example 2] Figure 11 This is a diagram of the lens structure of the zoom imaging optical system described in Example 2 when focusing at infinity at the wide-angle end.

[0167] Figure 11 The zoom imaging optical system consists of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM composed of a fourth lens group G4 and a fifth lens group G5, a focusing group GF composed of a sixth lens group G6, and a subsequent group GR composed of a seventh lens group G7, arranged sequentially from the object side.

[0168] The first lens group G1 consists of a combined lens of biconvex lens L1, biconvex lens L2, and biconcave lens L3. The second lens group G2 consists of a combined lens of biconvex lens L4 and a concave meniscus lens L5 with its convex surface facing the image side. The third lens group G3 consists of a combined lens of biconcave lens L6 and a convex meniscus lens L7 with its convex surface facing the object side, as well as a combined lens of biconcave lens L8, biconcave lens L9, and biconvex lens L10. Furthermore, the third lens group G3 can function as a vibration damping group by moving L8 to L10 integrally relative to the optical axis in a substantially perpendicular direction; however, lenses other than L8 to L10 can also be used as vibration damping groups. The fourth lens group G4 consists of a combined lens of biconvex lens L11, biconvex lens L12, and biconcave lens L13. The fifth lens group G5 consists of a combined lens of biconvex lens L14, biconcave lens L15, and biconvex lens L16, and an aperture stop S. Lens group G6 consists of a combined lens consisting of a biconvex lens L17 and a concave meniscus lens L18 with its convex surface facing the image side. Lens group G7 consists of a combined lens consisting of a convex meniscus lens L19 with its convex surface facing the image side and a biconcave lens L20; a combined lens consisting of a biconvex lens L21 and a concave meniscus lens L22 with its convex surface facing the image side; a combined lens consisting of a convex meniscus lens L23 with its convex surface facing the image side and a concave meniscus lens L24 with its convex surface facing the image side; and a combined lens consisting of a convex meniscus lens L25 with its convex surface facing the image side and a concave meniscus lens L26 with its convex surface facing the image side.

[0169] When zooming from the wide-angle end to the telephoto end, the third lens group G3 and the seventh lens group G7 are fixed relative to the image plane. The first lens group G1 moves towards the object side, the second lens group G2 moves towards the image side, the fourth lens group G4 and the fifth lens group G5 move towards the object side, and the sixth lens group G6 moves towards the image side after moving towards the object side. The spacing between the first lens group G1 and the second lens group G2 increases, the spacing between the second lens group G2 and the third lens group G3 decreases, the spacing between the third lens group G3 and the fourth lens group G4 decreases, the spacing between the fourth lens group G4 and the fifth lens group G5 decreases, the spacing between the fifth lens group G5 and the sixth lens group G6 increases, and the spacing between the sixth lens group G6 and the seventh lens group G7 increases and then decreases, becoming smaller relative to the wide-angle end at the telephoto end. When focusing from an object at infinity to a closer object, the sixth lens group G6 moves towards the object side.

[0170] L18 becomes a concave lens that satisfies condition (1). L3 becomes a concave lens that satisfies condition (2). L5 becomes a concave lens that satisfies condition (11). L22 and L24 become concave lenses that satisfy condition (12). L22 and L24 become concave lenses that satisfy condition (13). L21, L23 and L25 become convex lenses that satisfy condition (14). L23 and L25 become convex lenses that satisfy condition (15).

[0171] The following shows the specifications of the zoom imaging optical system involved in Example 2.

[0172] Numerical Example 2 (Unit: mm [area data]) [Various data] [Variable Interval Data] When focusing at infinity When focusing on close objects [Lens Group Data]

[0173] [Example 3] Figure 21 This is a diagram of the lens structure of the zoom imaging optical system described in Example 3 when focusing at infinity at the wide-angle end.

[0174] Figure 21 The zoom imaging optical system consists of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM composed of a fourth lens group G4, a fifth lens group G5 and a sixth lens group, a focusing group GF composed of a seventh lens group G7, and a subsequent group GR composed of an eighth lens group G8, arranged sequentially from the object side.

[0175] The first lens group G1 consists of a combined lens comprising a biconvex lens L1, a convex meniscus lens L2 with its convex surface facing the object side, and a concave meniscus lens L3 with its convex surface facing the object side. The second lens group G2 consists of a combined lens comprising a biconvex lens L4 and a concave meniscus lens L5 with its convex surface facing the image side. The third lens group G3 consists of a combined lens comprising a biconcave lens L6 and a convex meniscus lens L7 with its convex surface facing the object side, a biconcave lens L8, a biconcave lens L9, and a biconvex lens L10. Furthermore, the third lens group G3 can function as an anti-vibration group by moving L8 to L10 integrally relative to the optical axis in a substantially perpendicular direction; however, lenses other than L8 to L10 can also be used as an anti-vibration group. The fourth lens group G4 consists of a combined lens comprising a biconvex lens L11, a biconvex lens L12, and a concave meniscus lens L13 with its convex surface facing the image side. Lens group G5 (5th lens) consists of a combined lens of biconvex lens L14, biconcave lens L15, and biconvex lens L16, and an aperture stop S. Lens group G6 (6th lens) consists of a combined lens of biconvex lens L17 and a concave meniscus lens L18 with its convex surface facing the image side. Lens group G7 (7th lens) consists of a combined lens of convex meniscus lens L19 with its convex surface facing the image side and biconcave lens L20. Lens group G8 (8th lens) consists of a combined lens of biconvex lens L21 and biconcave lens L22, a combined lens of biconvex lens L23 and biconcave lens L24, a combined lens of convex meniscus lens L25 with its convex surface facing the image side and a concave meniscus lens L26 with its convex surface facing the image side.

[0176] When zooming from the wide-angle end to the telephoto end, the third lens group G3, the seventh lens group G7, and the eighth lens group G8 are fixed relative to the image plane. The first lens group G1 moves towards the object side, the second lens group G2 moves towards the image side, the fourth lens group G4 and the fifth lens group G5 move towards the object side, and the sixth lens group G6 moves towards the image 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, and the distance between the sixth lens group G6 and the seventh lens group G7 decreases. When focusing from an object at infinity to a closer object, the seventh lens group G7 moves towards the image side.

[0177] L18 becomes a concave lens that satisfies condition (1). L3 becomes a concave lens that satisfies condition (2). L5 becomes a concave lens that satisfies condition (11). L22 and L24 become concave lenses that satisfy condition (12). L22 and L24 become concave lenses that satisfy condition (13). L21, L23 and L25 become convex lenses that satisfy condition (14). L23 and L25 become convex lenses that satisfy condition (15).

[0178] The following shows the specifications of the zoom imaging optical system involved in Example 3.

[0179] Numerical Example 3 Unit: mm [Surface Data] [Various data] [Variable Interval Data] When focusing at infinity When focusing on close objects [Lens Group Data]

[0180] [Example 4] Figure 31 This is a diagram of the lens structure of the zoom imaging optical system described in Example 4 when focusing at infinity at the wide-angle end.

[0181] Figure 31 The zoom imaging optical system consists of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM composed of a fourth lens group G4 and a fifth lens group G5, a focusing group GF composed of a sixth lens group G6, and a subsequent group GR composed of a seventh lens group G7, arranged sequentially from the object side.

[0182] The first lens group G1 consists of a combined lens comprising a biconvex lens L1, a convex meniscus lens L2 with its convex surface facing the object side, and a concave meniscus lens L3 with its convex surface facing the object side. The second lens group G2 consists of a combined lens comprising a biconvex lens L4 and a concave meniscus lens L5 with its convex surface facing the image side. The third lens group G3 consists of a combined lens comprising a biconcave lens L6 and a convex meniscus lens L7 with its convex surface facing the object side, a concave meniscus lens L8 with its convex surface facing the object side, and a combined lens comprising a biconcave lens L9 and a biconvex lens L10. Furthermore, the third lens group G3 can function as an anti-vibration group by moving L8 to L10 integrally relative to the optical axis in a substantially perpendicular direction; however, lenses other than L8 to L10 can also function as an anti-vibration group. The fourth lens group G4 consists of a combined lens comprising a biconvex lens L11, a biconvex lens L12, and a biconcave lens L13. Lens group G5 (5th lens) consists of a combined lens of a biconvex lens L14, a concave meniscus lens L15 (convex side facing the object), and a biconvex lens L16, and an aperture stop S. Lens group G6 (6th lens) consists of a combined lens of a biconvex lens L17 and a concave meniscus lens L18 (convex side facing the image). Lens group G7 (7th lens) consists of a combined lens of a convex meniscus lens L19 (convex side facing the image) and a biconcave lens L20, a combined lens of a biconvex lens L21 and a concave meniscus lens L22 (convex side facing the image), a combined lens of a convex meniscus lens L23 (convex side facing the image) and a concave meniscus lens L24 (convex side facing the image), and a combined lens of a convex meniscus lens L25 (convex side facing the image) and a concave meniscus lens L26 (convex side facing the image).

[0183] When zooming from the wide-angle end to the telephoto end, the third lens group G3 and the seventh lens group G7 are fixed relative to the image plane. The first lens group G1 moves towards the object side, the second lens group G2 moves towards the image side, the fourth lens group G4 and the fifth lens group G5 move towards the object side, and the sixth lens group G6 moves towards the image side after moving towards the object side. The spacing between the first lens group G1 and the second lens group G2 increases, the spacing between the second lens group G2 and the third lens group G3 decreases, the spacing between the third lens group G3 and the fourth lens group G4 decreases, the spacing between the fourth lens group G4 and the fifth lens group G5 decreases, the spacing between the fifth lens group G5 and the sixth lens group G6 increases, and the spacing between the sixth lens group G6 and the seventh lens group G7 increases and then decreases, becoming smaller relative to the wide-angle end at the telephoto end. When focusing from an object at infinity to a closer object, the sixth lens group G6 moves towards the object side.

[0184] L18 becomes a concave lens that satisfies condition (1). L3 becomes a concave lens that satisfies condition (2). L5 becomes a concave lens that satisfies condition (11). L22 and L24 become concave lenses that satisfy condition (12). L22 and L24 become concave lenses that satisfy condition (13). L21, L23 and L25 become convex lenses that satisfy condition (14). L23 and L25 become convex lenses that satisfy condition (15).

[0185] The following shows the specifications of the zoom imaging optical system involved in Example 4.

[0186] Numerical Example 4 Unit: mm [Surface Data] [Various data] [Variable Interval Data] When focusing at infinity When focusing on close objects [Lens Group Data]

[0187] [Example 5] Figure 41 This is a diagram of the lens structure of the zoom imaging optical system described in Example 5 when focusing at infinity at the wide-angle end.

[0188] Figure 41 The zoom imaging optical system consists of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM composed of a fourth lens group G4 and a fifth lens group G5, a focusing group GF composed of a sixth lens group G6, and a subsequent group GR composed of a seventh lens group G7, arranged sequentially from the object side.

[0189] The first lens group G1 consists of a combined lens comprising a biconvex lens L1, a convex meniscus lens L2 with its convex surface facing the object side, a convex meniscus lens L3 with its convex surface facing the object side, and a concave meniscus lens L4 with its convex surface facing the object side. The second lens group G2 consists of a combined lens comprising a biconvex lens L5 and a concave meniscus lens L6 with its convex surface facing the image side. The third lens group G3 consists of a combined lens comprising a biconcave lens L7 and a convex meniscus lens L8 with its convex surface facing the object side, a biconcave lens L9, and a combined lens comprising a biconcave lens L10 and a biconvex lens L11. Furthermore, the third lens group G3 can function as an anti-vibration group by moving L9 to L11 integrally relative to the optical axis in a substantially perpendicular direction; however, lenses other than L9 to L11 can also function as an anti-vibration group. The fourth lens group G4 consists of a biconvex lens L12 and a combined lens comprising a biconvex lens L13 and a biconcave lens L14. Lens group G5 (5th lens) consists of a combined lens of biconvex lens L15, biconcave lens L16, and biconvex lens L17, and an aperture stop S. Lens group G6 (6th lens) consists of a combined lens of biconvex lens L18 and a concave meniscus lens L19 with its convex surface facing the image side. Lens group G7 (7th lens) consists of a combined lens of convex meniscus lens L20 with its convex surface facing the image side and biconcave lens L21, a combined lens of biconvex lens L22 and concave meniscus lens L23 with its convex surface facing the image side, a combined lens of convex meniscus lens L24 with its convex surface facing the image side and biconcave lens L25, and a combined lens of convex meniscus lens L26 with its convex surface facing the image side and concave meniscus lens L27 with its convex surface facing the image side.

[0190] When zooming from the wide-angle end to the telephoto end, the third lens group G3 and the seventh lens group G7 are fixed relative to the image plane. The first lens group G1 moves towards the object side, the second lens group G2 moves towards the image side, the fourth lens group G4 and the fifth lens group G5 move towards the object side, and the sixth lens group G6 moves slightly towards the image side. The spacing between the first lens group G1 and the second lens group G2 increases, the spacing between the second lens group G2 and the third lens group G3 decreases, the spacing between the third lens group G3 and the fourth lens group G4 decreases, the spacing between the fourth lens group G4 and the fifth lens group G5 decreases and then increases, and the spacing becomes larger relative to the wide-angle end at the telephoto end. The spacing between the fifth lens group G5 and the sixth lens group G6 increases, and the spacing between the sixth lens group G6 and the seventh lens group G7 decreases slightly. When focusing from an object at infinity to a closer object, the sixth lens group G6 moves towards the object side.

[0191] L19 becomes a concave lens that satisfies condition (1). L4 becomes a concave lens that satisfies condition (2). L6 becomes a concave lens that satisfies condition (11). L23 and L25 become concave lenses that satisfy condition (12). L23 and L25 become concave lenses that satisfy condition (13). L22, L24 and L26 become convex lenses that satisfy condition (14). L24 and L26 become convex lenses that satisfy condition (15).

[0192] The following shows the specifications of the zoom imaging optical system involved in Example 5.

[0193] Numerical Example 5 Unit: mm [Surface Data] Face number rd nd vd ΔPgF Corresponding glass material Object surface ∞ (d0) [Various data] [Variable Interval Data] When focusing at infinity When focusing on close objects [Lens Group Data]

[0194] [Example 6] Figure 51 This is a diagram of the lens structure of the zoom imaging optical system described in Example 6 when focusing at infinity at the wide-angle end.

[0195] Figure 51 The zoom imaging optical system consists of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM composed of a fourth lens group G4 and a fifth lens group G5, a focusing group GF composed of a sixth lens group G6, and a subsequent group GR composed of a seventh lens group G7, arranged sequentially from the object side.

[0196] The first lens group G1 consists of a combined lens of biconvex lens L1, biconvex lens L2, and biconcave lens L3. The second lens group G2 consists of a combined lens of biconvex lens L4 and a concave meniscus lens L5 with its convex surface facing the image side. The third lens group G3 consists of a combined lens of biconcave lens L6 and biconvex lens L7, a biconcave lens L8, and a combined lens of biconcave lens L9 and biconvex lens L10. Furthermore, the third lens group G3 can function as a vibration damping group by moving L8 to L10 integrally relative to the optical axis in a substantially perpendicular direction; however, lenses other than L8 to L10 can also be used as vibration damping groups. The fourth lens group G4 consists of a combined lens of biconvex lens L11, biconvex lens L12, and biconcave lens L13. The fifth lens group G5 consists of a combined lens of biconvex lens L14, biconcave lens L15, and a convex meniscus lens L16 with its convex surface facing the object side, and an aperture stop S. Lens group G6 consists of a combined lens of a biconvex lens L17 and a concave meniscus lens L18 with its convex surface facing the image side. Lens group G7 consists of a combined lens of a biconcave aspherical lens L19 with aspherical surfaces on both the object and image sides, a combined lens of a biconvex lens L20 and a biconcave lens L21, a combined lens of a biconvex lens L22 and a biconcave lens L23, a combined lens of a biconvex lens L24 and a biconcave lens L25, a combined lens of a biconvex lens L26 and a concave meniscus lens L27 with its convex surface facing the image side, and a concave meniscus lens L28 with its convex surface facing the image side.

[0197] When zooming from the wide-angle end to the telephoto end, the third lens group G3 and the seventh lens group G7 are fixed relative to the image plane. The first lens group G1 moves towards the object side, the second lens group G2 moves towards the image side, the fourth lens group G4 and the fifth lens group G5 move towards the object side, and the sixth lens group G6 moves towards the image side after moving towards the object side. The spacing between the first lens group G1 and the second lens group G2 increases, the spacing between the second lens group G2 and the third lens group G3 decreases, the spacing between the third lens group G3 and the fourth lens group G4 decreases, the spacing between the fourth lens group G4 and the fifth lens group G5 decreases, the spacing between the fifth lens group G5 and the sixth lens group G6 increases, and the spacing between the sixth lens group G6 and the seventh lens group G7 increases and then decreases, becoming smaller relative to the wide-angle end at the telephoto end. When focusing from an object at infinity to a closer object, the sixth lens group G6 moves towards the object side.

[0198] L18 becomes a concave lens that satisfies condition (1). L3 becomes a concave lens that satisfies condition (2). L5 becomes a concave lens that satisfies condition (11). L25 and L27 become concave lenses that satisfy condition (12). L25 and L27 become concave lenses that satisfy condition (13). L24 and L26 become convex lenses that satisfy condition (14). L24 and L26 become convex lenses that satisfy condition (15).

[0199] The following shows the specifications of the zoom imaging optical system involved in Example 6.

[0200] Numerical Example 6 Unit: mm [Surface Data] [Aspherical Data] [Various data] [Variable Interval Data] When focusing at infinity When focusing on close objects [Lens Group Data]

[0201] Furthermore, a list of corresponding values ​​for the conditional expressions in these various embodiments is shown.

[0202] [Conditional expression corresponding value]

[0203] Furthermore, this technology can also adopt the following structure. [Item 1] A zoom imaging optical system, characterized in that, It consists of a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, an intermediate group GM including one or more lens groups and an aperture stop S, a focusing group GF, and a subsequent group GR consisting of one lens group, arranged sequentially from the object side. The spacing between adjacent lens groups changes when zooming. When focusing from an object at infinity to a closer object, the focusing group GF moves along the optical axis. [Item 2] The zoom imaging optical system according to [item 1] is characterized in that, One or more concave lenses satisfying the following condition (1) are disposed between the aperture stop S and the subsequent group GR. (1) ΔPgFLnSr>0.013 ΔPgFLnSr: Anomalous dispersion of the concave lens positioned between the aperture stop S and the subsequent group GR. [Item 3] The zoom imaging optical system according to [item 1] or [item 2] is characterized in that, When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves towards the object side, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases. [Item 4] The zoom imaging optical system according to any one of [items 1] to [items 3] is characterized in that, When zooming from the wide-angle end to the telephoto end, the second lens group G2 moves towards 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. [Item 5] The zoom imaging optical system according to any one of [items 1] to [items 4] is characterized in that, The first lens group G1 includes a concave lens that satisfies the following condition (2). (2)ndLN1 < 1.80 ndLN1: The refractive index of the concave lens with the highest refractive index included in the first lens group G1. [Item 6] The zoom imaging optical system according to any one of [items 1] to [items 5] is characterized in that, The following condition (3) is satisfied. (3)0.005<DG1G2W / DG1G2T<0.400 DG1G2W: The optical axis spacing between the first lens group G1 and the second lens group G2 at the infinity wide-angle end. DG1G2T: The optical axis spacing between the first lens group G1 and the second lens group G2 at the far end of the infinity telescope. [Item 7] The zoom imaging optical system according to any one of [items 1] to [items 6] is characterized in that, The following condition (4) is satisfied. (4)1.00<DG2G3W / DG2G3T<80.00 DG2G3W: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end. DG2G3T: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the far end of the infinity telescope. [Item 8] The zoom imaging optical system according to any one of [items 1] to [items 7] is characterized in that, The following condition (5) is satisfied. (5)0.01<DG1G2W / DG2G3W<2.00 DG1G2W: The optical axis spacing between the first lens group G1 and the second lens group G2 at the infinity wide-angle end. DG2G3W: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the infinity wide-angle end. [Item 9] The zoom imaging optical system according to any one of [items 1] to [items 8] is characterized in that, The following condition (6) must be satisfied. (6)2.0<DG1G2T / DG2G3T<200.0 DG1G2T: The optical axis spacing between the first lens group G1 and the second lens group G2 at the far end of the infinity telescope. DG2G3T: The spacing on the optical axis between the second lens group G2 and the third lens group G3 at the far end of the infinity telescope. [Item 10] The zoom imaging optical system according to any one of [items 1] to [items 9] is characterized in that, The following condition (7) is satisfied. (7) 1.2 < DG2Sw / DG2St < 5.0 DG2Sw: The distance from the top of the lens surface closest to the object in the second lens group G2 at the wide-angle end to the aperture stop S. DG2St: The distance from the top of the surface of the lens closest to the object in the second lens group G2 at the telephoto end to the aperture stop S. [Item 11] The zoom imaging optical system according to any one of [items 1] to [items 10] is characterized in that, The second lens group G2 satisfies the following condition (8). (8) 0.2 < g2AXhW / g2AXhT < 1.5 g2AXhW: The height of the on-axis edge ray at the infinity wide-angle end of the aperture stop on the surface in front of the second lens group G2. g2AXhT: The height of the on-axis edge ray at the far end of the infinity lens with the aperture open at the top of the telescope on the surface in front of the second lens group G2. [Item 12] The zoom imaging optical system according to any one of [items 1] to [items 11] is characterized in that, The second lens group G2 satisfies the following conditions (9) and (10). (9)-1.8<(g2OAhW / Wih)-(g2OAhT / Tih)<-0.3 (10)0.6<|g2OAhW / g2AXhT|<2.5 Wih: Image height of the off-axis principal ray at the maximum field of view at infinity. Tih: Image height of the off-axis principal ray at the maximum field of view of the telescope at infinity. g2OAhW: The height of the off-axis principal ray at the maximum field of view at infinity on the plane in front of the second lens group G2. g2OAhT: The height of the off-axis principal ray at the maximum field of view at the far end of the infinity telescope on the plane in front of the second lens group G2. g2AXhT: The height of the on-axis edge ray at the far end of the infinity lens with the aperture open at the top of the telescope on the surface in front of the second lens group G2. [Item 13] The zoom imaging optical system according to any one of [items 1] to [items 12] is characterized in that, The second lens group G2 includes one or more concave lenses. [Item 14] The zoom imaging optical system according to any one of [items 1] to [items 13] is characterized in that, The second lens group G2 includes at least one concave lens that satisfies the following condition (11). (11) ΔPgFLg2>0.0090 ΔPgFLg2: The anomalous dispersion of the concave lens with the greatest anomalous dispersion among the concave lenses included in the second lens group G2. [Item 15] The zoom imaging optical system according to any one of [items 1] to [items 14] is characterized in that, The subsequent group GR includes at least one concave lens that satisfies the following condition (12). (12) ΔPgFnLr>0.009 ΔPgFnLr: Anomalous dispersion of the concave lens in the subsequent GR group [Item 16] The zoom imaging optical system according to any one of [items 1] to [items 15] is characterized in that, The subsequent group GR includes at least one concave lens that satisfies the following condition (13). (13) vdnLr×ΔPgFnLr>0.80 vdnLr: Abbe number of the concave lenses included in the subsequent group GR. ΔPgFnLr: Anomalous dispersion of the concave lenses included in the subsequent group GR [Item 17] The zoom imaging optical system according to any one of [items 1] to [items 16] is characterized in that, The subsequent group GR includes at least one convex lens that satisfies the following condition (14). (14)ΔPgFpLr<-0.0010 ΔPgFpLr: Anomalous dispersion of the convex lens included in the subsequent group GR [Item 18] The zoom imaging optical system according to any one of [items 1] to [items 17] is characterized in that, The two convex lenses, measured from the image side, satisfy the following condition (15). (15)ΔPgFprAVE<-0.0010 ΔPgFprAVE: The average value of the anomalous dispersion of the two convex lenses closest to the image side. [Item 19] The zoom imaging optical system according to any one of [items 1] to [items 18] is characterized in that, The first lens group G1 satisfies the following condition (16). (16) 0.18 < f1 / fT < 1.00 f1: Focal length of the first lens group G1 fT: Focal length of the zoom imaging optical system at the far end of an infinity telescope. [Item 20] The zoom imaging optical system according to any one of [items 1] to [items 19] is characterized in that, The second lens group G2 satisfies the following condition (17). (17) 0.1 < f2 / fT < 1.4 f2: Focal length of the second lens group G2 fT: Focal length of the zoom imaging optical system at the far end of an infinity telescope. [Item 21] The zoom imaging optical system according to any one of [item 1] to [item 20] is characterized in that the first lens group G1 and the second lens group G2 satisfy the following condition (18). (18) 0.6 < f1 / f2 < 2.2 f1: Focal length of the first lens group G1 f2: Focal length of the second lens group G2 [Item 22] The zoom imaging optical system according to any one of [items 1] to [items 21] is characterized in that, The following condition (19) is satisfied. (19) 1.0 < f1 / fW < 5.0 f1: Focal length of the first lens group G1 fW: Focal length of the zoom imaging optical system at infinity wide-angle end [Item 23] The zoom imaging optical system according to any one of [items 1] to [items 22] is characterized in that, The following condition (20) is satisfied. (20) 0.5 < f2 / fW < 8.5 f2: Focal length of the second lens group G2 fW: Focal length of the zoom imaging optical system at infinity wide-angle end [Item 24] The zoom imaging optical system according to any one of [item 1] to [item 23] is characterized in that the focusing group GF satisfies the following condition (21). (21) 0.04 < |fF / fT| < 0.35 fF: Focal length of the focus group GF fT: Focal length of the zoom imaging optical system at the far end of an infinity telescope. [Item 25] The zoom imaging optical system according to any one of [items 1] to [items 24] is characterized in that, The following condition (22) is satisfied. (22)2.0<|{1-(βFT)^2}×(βRT)^2|<20.0 βFT: Horizontal magnification at infinity telephoto end of the GF focus group. βRT: Lateral magnification at infinity for all lens groups positioned closer to the image side than the focusing group GF. [Item 26] The zoom imaging optical system according to any one of [items 1] to [items 25] is characterized in that, The third lens group G3 is fixed relative to the image plane during zoom. [Item 27] The zoom imaging optical system according to any one of [items 1] to [items 26] is characterized in that, The subsequent group GR is fixed relative to the image plane during zooming. Symbol Explanation

[0204] G1 - Lens Group 1, G2 - Lens Group 2, G3 - Lens Group 3, G4 - Lens Group 4, G5 - Lens Group 5, G6 - Lens Group 6, G7 - Lens Group 7, G8 - Lens Group 8, GM - Intermediate Group, GF - Focusing Group, GR - Rear Group, S - Aperture Stop, F - Filter, I - Image Plane.

Claims

1. A zoom imaging optical system, characterized in that, It consists of a first lens group (G1) with positive refractive power, a second lens group (G2) with positive refractive power, a third lens group (G3) with negative refractive power, an intermediate group (GM) including one or more lens groups and an aperture stop (S), a focusing group (GF), and a subsequent group (GR) consisting of one lens group, arranged sequentially from the object side. The spacing between adjacent lens groups changes during zooming. When focusing from an object at infinity to a closer object, the focusing group (GF) moves along the optical axis.

2. The zoom imaging optical system according to claim 1, characterized in that, One or more concave lenses satisfying the following condition (1) are disposed between the aperture stop (S) and the subsequent group (GR). (1) ΔPgFLnSr>0.013 ΔPgFLnSr is the anomalous dispersion of a concave lens positioned between the aperture stop (S) and the subsequent group (GR).

3. The zoom imaging optical system according to claim 1, characterized in that, When zooming from the wide-angle end to the telephoto end, the first lens group (G1) moves towards the object side, the distance between the first lens group (G1) and the second lens group (G2) increases, and the distance between the second lens group (G2) and the third lens group (G3) decreases.

4. The zoom imaging optical system according to claim 1, characterized in that, When zooming from the wide-angle end to the telephoto end, the second lens group (G2) moves towards 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.

5. The zoom imaging optical system according to claim 1, characterized in that, The first lens group (G1) includes a concave lens that satisfies the following condition (2). (2)ndLN1 < 1.80 ndLN1 is the refractive index of the concave lens with the highest refractive index included in the first lens group (G1).

6. The zoom imaging optical system according to claim 1, characterized in that, The following condition (3) must be met. (3)0.005<DG1G2W / DG1G2T<0.400 DG1G2W is the optical axis spacing between the first lens group (G1) and the second lens group (G2) at the infinity wide-angle end. DG1G2T is the optical axis spacing between the first lens group (G1) and the second lens group (G2) at the telephoto end of an infinity telescope.

7. The zoom imaging optical system according to claim 1, characterized in that, The following condition (4) must be met. (4)1.00<DG2G3W / DG2G3T<80.00 DG2G3W represents the optical axis spacing between the second lens group (G2) and the third lens group (G3) at the infinity wide-angle end. DG2G3T is the optical axis spacing between the second lens group (G2) and the third lens group (G3) at the telephoto end of an infinity telescope.

8. The zoom imaging optical system according to claim 1, characterized in that, The following condition (5) must be met. (5)0.01<DG1G2W / DG2G3W<2.00 DG1G2W is the optical axis spacing between the first lens group (G1) and the second lens group (G2) at the infinity wide-angle end. DG2G3W is the optical axis spacing between the second lens group (G2) and the third lens group (G3) at the infinity wide-angle end.

9. The zoom imaging optical system according to claim 1, characterized in that, The following condition (6) must be met. (6)2.0<DG1G2T / DG2G3T<200.0 DG1G2T is the optical axis spacing between the first lens group (G1) and the second lens group (G2) at the telephoto end of an infinity telescope. DG2G3T is the optical axis spacing between the second lens group (G2) and the third lens group (G3) at the telephoto end of an infinity telescope.

10. The zoom imaging optical system according to claim 1, characterized in that, The following condition (7) must be met. (7) 1.2 < DG2Sw / DG2St < 5.0 DG2Sw is the distance from the top of the lens surface of the second lens group (G2) closest to the object to the aperture stop (S) at the wide-angle end. DG2St is the distance from the top of the lens face of the second lens group (G2) closest to the object to the aperture stop (S) at the telephoto end.

11. The zoom imaging optical system according to claim 1, characterized in that, The second lens group (G2) satisfies the following condition (8), (8) 0.2 < g2AXhW / g2AXhT < 1.5 g2AXhW is the height of the on-axis edge ray at the widest angle of the aperture when it is open at infinity on the plane in front of the second lens group (G2). g2AXhT is the height of the on-axis edge ray at the far end of the infinity lens with the aperture open, on the plane in front of the second lens group (G2).

12. The zoom imaging optical system according to claim 1, characterized in that, The second lens group (G2) satisfies the following conditions (9) and (10). (9)-1.8<(g2OAhW / Wih)-(g2OAhT / Tih)<-0.3 (10)0.6<|g2OAhW / g2AXhT|<2.5 Wih is the image height of the off-axis principal ray at the maximum field of view at infinity. Tih is the image height of the off-axis principal ray at the maximum field of view of the telescope at infinity. g2OAhW is the height of the off-axis principal ray at the maximum field of view at infinity on the plane in front of the second lens group (G2). g2OAhT is the height of the off-axis principal ray at the maximum field of view at the far end of the infinity telescope, on the plane in front of the second lens group (G2). g2AXhT is the height of the on-axis edge ray at the far end of the infinity lens with the aperture open, on the plane in front of the second lens group (G2).

13. The zoom imaging optical system according to claim 1, characterized in that, The second lens group (G2) includes one or more concave lenses.

14. The zoom imaging optical system according to claim 1, characterized in that, The second lens group (G2) includes at least one concave lens that satisfies the following condition (11). (11) ΔPgFLg2>0.0090 ΔPgFLg2 is the anomalous dispersion of the concave lens with the greatest anomalous dispersion among the concave lenses included in the second lens group (G2).

15. The zoom imaging optical system according to claim 1, characterized in that, The subsequent group (GR) includes at least one concave lens satisfying the following condition (12): (12) ΔPgFnLr>0.009 ΔPgFnLr is the anomalous dispersion of the concave lens in the subsequent group (GR).

16. The zoom imaging optical system according to claim 1, characterized in that, The subsequent group (GR) includes at least one concave lens satisfying the following condition (13): (13) vdnLr×ΔPgFnLr>0.80 vdnLr is the Abbe number of the concave lenses included in the subsequent group (GR). ΔPgFnLr is the anomalous dispersion of the concave lens included in the subsequent group (GR).

17. The zoom imaging optical system according to claim 1, characterized in that, The subsequent group (GR) includes at least one convex lens that satisfies the following condition (14): (14) ΔPgFpLr < -0.0010 ΔPgFpLr is the anomalous dispersion of the convex lens included in the subsequent group (GR).

18. The zoom imaging optical system according to claim 1, characterized in that, The two convex lenses, counting from the image side, satisfy the following condition (15). (15) ΔPgFprAVE<-0.0010 ΔPgFprAVE is the average value of the anomalous dispersion of the two convex lenses from the image side.

19. The zoom imaging optical system according to claim 1, characterized in that, The first lens group (G1) satisfies the following condition (16), (16) 0.18 < f1 / fT < 1.00 f1 is the focal length of the first lens group (G1). fT is the focal length of the zoom imaging optical system at the infinity telephoto end.

20. The zoom imaging optical system according to claim 1, characterized in that, The second lens group (G2) satisfies the following condition (17), (17) 0.1 < f2 / fT < 1.4 f2 is the focal length of the second lens group (G2). fT is the focal length of the zoom imaging optical system at the infinity telephoto end.

21. The zoom imaging optical system according to claim 1, characterized in that, The first lens group (G1) and the second lens group (G2) satisfy the following condition (18), (18) 0.6 < f1 / f2 < 2.2 f1 is the focal length of the first lens group (G1). f2 is the focal length of the second lens group (G2).

22. The zoom imaging optical system according to claim 1, characterized in that, The following condition (19) must be satisfied. (19) 1.0 < f1 / fW < 5.0 f1 is the focal length of the first lens group (G1). fW is the focal length of the zoom imaging optical system at the infinity wide-angle end.

23. The zoom imaging optical system according to claim 1, characterized in that, The following condition (20) must be met. (20) 0.5 < f2 / fW < 8.5 f2 is the focal length of the second lens group (G2). fW is the focal length of the zoom imaging optical system at the infinity wide-angle end.

24. The zoom imaging optical system according to claim 1, characterized in that, The focusing group (GF) satisfies the following condition (21), (21) 0.04 < |fF / fT| < 0.35 fF is the focal length of the focus group (GF). fT is the focal length of the zoom imaging optical system at the infinity telephoto end.

25. The zoom imaging optical system according to claim 1, characterized in that, The following condition (22) must be satisfied. (22)2.0<|{1-(βFT)^2}×(βRT)^2|<20.0 βFT is the lateral magnification at the infinity telephoto end of the focus group (GF). βRT is the lateral magnification at infinity for all lens groups positioned further to the image side than the focusing group (GF).

26. The zoom imaging optical system according to claim 1, characterized in that, The third lens group (G3) is fixed relative to the image plane when zooming.

27. The zoom imaging optical system according to claim 1, characterized in that, The subsequent group (GR) is fixed relative to the image plane when zoomed.

Images