Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B15/00—Optical objectives with means for varying the magnification
  • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
  • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B13/00—Optical objectives specially designed for the purposes specified below
  • G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B15/00—Optical objectives with means for varying the magnification
  • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
  • G02B15/144—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only
  • G02B15/1441—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B15/00—Optical objectives with means for varying the magnification
  • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
  • G02B15/145—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only
  • G02B15/1451—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being positive
  • G02B15/145121—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being positive arranged +-+-+
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B15/00—Optical objectives with means for varying the magnification
  • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
  • G02B15/146—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having more than five groups
  • G02B15/1461—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having more than five groups the first group being positive
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B15/00—Optical objectives with means for varying the magnification
  • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
  • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
  • G02B15/163—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group
  • G02B15/167—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses
  • G02B15/173—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses arranged +-+
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B15/00—Optical objectives with means for varying the magnification
  • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
  • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
  • G02B15/20—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having an additional movable lens or lens group for varying the objective focal length

Definitions

• the technology disclosed herein relates to a variable magnification optical system and an imaging device.
• zoom lenses described in JP 2016-109720 A, JP 2016-109721 A, and JP 2021-009217 A are known as variable magnification optical systems that can be used in imaging devices such as digital cameras.
• variable magnification optical systems that are compact, have a small F-number over the entire range of magnification, and have high optical performance over the entire range of magnification. These requirements are becoming higher every year.
• the present disclosure provides a variable magnification optical system that is compact, has a small F-number over the entire range of magnification, and has high optical performance over the entire range of magnification, and an imaging device equipped with this variable magnification optical system.
• a variable power optical system includes, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, an intermediate group, and a final lens group having refractive power, the intermediate group being composed of one or more and five or less lens groups, and during variable power, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the intermediate group changes, and a distance between the intermediate group and the final lens group changes, and when the intermediate group is composed of a plurality of lens groups, all distances between adjacent lens groups in the intermediate group change during variable power, an aperture stop is disposed between the lens surface closest to the image side of the second lens group and the lens surface closest to the object side of the final lens group, and the first lens group includes, in order from the most object side to the image side, a first lens which is a negative lens, a positive lens, and a second lens which is arranged so as to face the aperture stop, and when the focal length
• variable magnification optical system 1 ⁇ fw/(ft ⁇ tan ⁇ t) ⁇ 1.4 (4) It is preferable to satisfy conditional expression (4) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: ⁇ 6.6 ⁇ f1/fL1STw ⁇ 1.5 (5) It is preferable to satisfy conditional expression (5) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: ⁇ 0.9 ⁇ f1/fL1 ⁇ 0.05 (6) It is preferable to satisfy conditional expression (6) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: ⁇ 1.4 ⁇ fw/fL1STw ⁇ 0.3 (7) It is preferable to satisfy conditional expression (7) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 1 ⁇ fw/(ft ⁇ tan ⁇ t) ⁇ 1.4 (4) ⁇ 6.6 ⁇ f1/fL1STw ⁇ 1.5 (5) ⁇ 0.9 ⁇ f1/fL1 ⁇ 0.05 (6) ⁇ 1.4 ⁇ fw/fL1STw ⁇ 0.3 (7) It is preferable to satisfy the conditional expressions (4), (5), (6), and (7) represented by the following:
• variable magnification optical system is 2 ⁇ TLw/(ft ⁇ tan ⁇ t) ⁇ 9 (8) It is preferable to satisfy conditional expression (8) expressed as follows:
• variable magnification optical system of the above aspect has the following formula: 1.1 ⁇ ⁇ 2t / ⁇ 2w ⁇ 3 (9) It is preferable to satisfy conditional expression (9) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.1 ⁇
• variable magnification optical system of the above aspect has the following characteristics: 0.2 ⁇ DDL1STw/f1 ⁇ 0.8 (11) It is preferable to satisfy conditional expression (11) expressed as follows:
• variable magnification optical system of the above aspect has the following: 3 ⁇ DDL1STw/ ⁇ (fw ⁇ tan ⁇ w) ⁇ log(ft/fw) ⁇ / ⁇ 9 (12) It is preferable to satisfy conditional expression (12) expressed as follows:
• variable magnification optical system 3 ⁇ TLw/fw ⁇ 8 (13) It is preferable to satisfy conditional expression (13) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 1.5 ⁇ TLt/ft ⁇ 3 (14) It is preferable to satisfy conditional expression (14) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 5 ⁇ TLt/(ft ⁇ tan ⁇ t) ⁇ 11 (15) It is preferable to satisfy conditional expression (15) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 3 ⁇ f1/fw ⁇ 7 (16) It is preferable to satisfy conditional expression (16) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 3 ⁇ f1/(-f2) ⁇ 9 (17) It is preferable to satisfy conditional expression (17) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 2 ⁇ f1/(ft/Fnot) ⁇ 7 (18) It is preferable to satisfy conditional expression (18) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 1.8 ⁇ f1/(fw ⁇ ft) 1/2 ⁇ 4.2 (19) It is preferable to satisfy conditional expression (19) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 2 ⁇ Den/ ⁇ (f ⁇ tan ⁇ ) ⁇ log(ft/f) ⁇ 4.5 (20) It is preferable to satisfy conditional expression (20) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 0.5 ⁇ Denw/(fw ⁇ ft) 1/2 ⁇ 1 (21) It is preferable to satisfy conditional expression (21) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.04 ⁇ d1/(Den ⁇ tan ⁇ ) ⁇ 0.09 (22) It is preferable to satisfy conditional expression (22) expressed as follows:
• Dexw The distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity at the wide-angle end is Dexw, and the sign of Dexw is positive for the distance on the image side and negative for the distance on the object side with respect to the image plane.
• Dexw is calculated using the air equivalent distance for the optical element.
• variable magnification optical system of the above aspect is as follows: 1.5 ⁇ EDf/EDr ⁇ 3 (24) It is preferable to satisfy conditional expression (24) expressed as follows:
• variable magnification optical system of the above aspect has the following: 0.35 ⁇ EDf/TLw ⁇ 0.65 (25) It is preferable to satisfy conditional expression (25) expressed as follows:
• variable magnification optical system is 2.2 ⁇ ft/fw ⁇ 4.8 (26) It is preferable to satisfy conditional expression (26) expressed as follows:
• variable magnification optical system of the above embodiment has the following properties: 1.8 ⁇ NdL1 ⁇ 2.01 (27) 15 ⁇ dL1 ⁇ 45 (28) 2 ⁇ NdL1+0.01 ⁇ dL1 ⁇ 2.5 (29) It is preferable to satisfy the conditions (27), (28), and (29) represented by the following:
• variable magnification optical system of the above embodiment has the following properties: 1.43 ⁇ NdL2 ⁇ 1.81 (30) 45 ⁇ dL2 ⁇ 96 (31) 2 ⁇ NdL2+0.01 ⁇ dL2 ⁇ 2.5 (32) It is preferable to satisfy the conditions (30), (31), and (32) represented by the following:
• the variable magnification optical system includes at least one focusing group that moves during magnification change and during focusing. If the focal length of the focusing group with the smallest absolute focal length value among the focusing groups included in the variable magnification optical system is ffoc, and the focal length of the intermediate group when focused on an object at infinity at the telephoto end is fMt, then the variable magnification optical system of the above aspect can be expressed as follows: 0.3 ⁇
• variable magnification optical system of the above aspect includes at least one focusing group that moves during magnification change and focusing, and when the lateral magnification of the focusing group with the largest absolute value of focal length among the focusing groups included in the variable magnification optical system is ⁇ ft when focused on an object at infinity at the telephoto end, and when the composite lateral magnification of all lenses on the image side of the focusing group with the largest absolute value of focal length is ⁇ fRt when focused on an object at infinity at the telephoto end, 1 ⁇
• One of the lens groups included in the intermediate group may be configured to be a focusing group that moves when varying magnification and when focusing.
• the focusing group may be configured to include one positive lens and two negative lenses.
• the negative lens closest to the image side of the focusing group is an aspheric lens
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcnf
• the paraxial radius of curvature of the image side surface of the aspheric lens is Rcnr
• the radius of curvature of the object side surface of the aspheric lens at the position of the maximum effective diameter is Rynf
• the radius of curvature of the image side surface of the aspheric lens at the position of the maximum effective diameter is Rynr
• the variable magnification optical system of the above aspect is as follows: 0.1 ⁇ (1/Rcnf-1/Rcnr)/(1/Rynf-1/Rynr) ⁇ 3 (35) It is preferable to satisfy conditional expression (35) expressed as follows:
• the focusing group may be configured to include one negative lens and two positive lenses.
• the positive lens closest to the image side of the focusing group is an aspheric lens
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcpf
• the paraxial radius of curvature of the image side surface of the aspheric lens is Rcpr
• the radius of curvature of the object side surface of the aspheric lens at the position of the maximum effective diameter is Rypf
• the radius of curvature of the image side surface of the aspheric lens at the position of the maximum effective diameter is Rypr
• the variable magnification optical system of the above aspect is as follows: ⁇ 120 ⁇ (1/Rcpf ⁇ 1/Rcpr)/(1/Rypf ⁇ 1/Rypr) ⁇ 3 (36) It is preferable to satisfy conditional expression (36) expressed as follows:
• the focusing group may be configured to consist of one positive lens and one negative lens.
• the focusing group may be configured to be composed of one negative lens.
• the negative lens of the focusing group is an aspheric lens
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcsnf
• the paraxial radius of curvature of the image side surface of the aspheric lens is Rcsnr
• the radius of curvature of the object side surface of the aspheric lens at the position of the maximum effective diameter is Rysnf
• the radius of curvature of the image side surface of the aspheric lens at the position of the maximum effective diameter is Rysnr
• the variable magnification optical system of the above aspect is as follows: 0.1 ⁇ (1/Rcsnf-1/Rcsnr)/(1/Rysnf-1/Rysnr) ⁇ 3.5 (37) It is preferable to satisfy conditional expression (37) expressed as follows:
• Two of the lens groups included in the intermediate group may be configured as focusing groups that move while changing the distance between them when changing magnification and when focusing.
• the lens group arranged on the object side is the object side focusing group
• the lens group arranged on the image side is the image side focusing group
• the object side focusing group may be configured to consist of one negative lens and one positive lens
• the image side focusing group may be configured to consist of one positive lens
• the variable magnification optical system of the above aspect is as follows: 1 ⁇ (1/Rcipf-1/Rcipr)/(1/Ryipf-1/Ryipr) ⁇ 100 (38) It is preferable to satisfy conditional expression (38) expressed as follows:
• the lens group arranged on the object side is designated as the object side focusing group
• the lens group arranged on the image side is designated as the image side focusing group
• the object side focusing group may be configured to consist of one positive lens and one negative lens
• the image side focusing group may be configured to consist of one negative lens
• the variable magnification optical system of the above aspect is as follows: 0.1 ⁇ (1/Rcinf-1/Rcinr)/(1/Ryinf-1/Ryinr) ⁇ 3.5 (39) It is preferable to satisfy conditional expression (39) expressed as follows:
• variable magnification optical system of the above aspect may be configured to include multiple lens groups that move along the same movement trajectory when changing magnification from the wide-angle end to the telephoto end.
• the intermediate group includes an aperture stop closest to the object.
• the intermediate group may be configured to consist, in order from the object side to the image side, of a lens group having positive refractive power and a lens group having negative refractive power, and the final lens group may be configured to have positive refractive power.
• the final lens group may be configured to be fixed relative to the image plane during zooming.
• the variable magnification optical system of the above aspect has the following characteristics: 0.1 ⁇
• the final lens group may be configured to move when changing magnification.
• the intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having negative refractive power, and the final lens group may be configured to have positive refractive power.
• the final lens group may be configured to move when changing magnification.
• the intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power.
• the final lens group may be configured to move during zooming.
• the intermediate group may be configured to consist of, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group may be configured to have positive refractive power.
• the final lens group may be configured to move when changing magnification.
• the intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power.
• the final lens group may be configured to move when changing magnification.
• the intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power.
• the final lens group may be configured to move when changing magnification.
• the intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group may be configured to have positive refractive power.
• the final lens group may be configured to move when changing magnification.
• the intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power.
• the final lens group may be configured to move when changing magnification.
• An imaging device includes a variable magnification optical system according to the above aspect of the present disclosure.
• the invention may also include lenses that have substantially no refractive power, optical elements other than lenses such as apertures, filters, and cover glasses, as well as mechanical parts such as lens flanges, lens barrels, image sensors, and image stabilization mechanisms.
• a lens group having positive refractive power and “the lens group has positive refractive power” mean that the lens group as a whole has positive refractive power.
• a lens group having negative refractive power and “the lens group has negative refractive power” mean that the lens group as a whole has negative refractive power.
• the "first lens group,” “second lens group,” “lens group,” “final lens group,” and “focusing group” are not limited to configurations consisting of multiple lenses, and may be configurations consisting of only one lens.
• Composite aspherical lenses (lenses in which a spherical lens and an aspherical film formed on the spherical lens are integrated together and function as a single aspherical lens as a whole) are not considered cemented lenses, but are treated as a single lens.
• the sign of the refractive power and surface shape of lenses that include aspheric surfaces are those in the paraxial region.
• the sign of the radius of curvature is positive for the surface with a convex shape facing the object side, and negative for the surface with a convex shape facing the image side.
• total system means a variable magnification optical system.
• focal length used in the conditional expressions is the paraxial focal length.
• distance on the optical axis used in the conditional expressions is the geometric distance unless otherwise specified.
• values used in the conditional expressions are values based on the d-line when focused on an object at infinity, unless otherwise specified.
• the "d-line,” “C-line,” “F-line,” and “g-line” mentioned in this specification are emission lines.
• the wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line as 656.27 nm (nanometers), the wavelength of the F-line as 486.13 nm (nanometers), and the wavelength of the g-line as 435.84 nm (nanometers).
• the present disclosure makes it possible to provide a variable magnification optical system that is compact, has a small F-number over the entire range of magnification, and has high optical performance over the entire range of magnification, and an imaging device equipped with this variable magnification optical system.
• 1A and 1B correspond to the variable magnification optical system of Example 1, and are diagrams showing a cross-sectional view of the configuration of a variable magnification optical system according to one embodiment and a movement locus.
• FIG. 13 is a diagram for explaining symbols in a conditional expression.
• FIG. 2 is a diagram for explaining the positions of an effective diameter and a maximum effective diameter.
• 3A to 3C are diagrams showing various aberrations of the variable magnification optical system of Example 1.
• 11A and 11B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a second embodiment.
• 11A to 11C are diagrams showing various aberrations in the variable magnification optical system according to the second embodiment.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a third embodiment.
• 11A to 11C are diagrams showing various aberrations in the variable magnification optical system according to Example 3.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fourth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to Example 4.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fifth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to the fifth embodiment.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a sixth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to Example 6.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a seventh embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system of Example 7.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to an eighth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to Example 8.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a ninth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to Example 9.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a tenth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system of Example 10.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to an eleventh embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system of Example 11.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twelfth embodiment of the present invention.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 12.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a thirteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 13.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fourteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 14.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fifteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 15.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a sixteenth embodiment of the present invention.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 16.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a seventeenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 17.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of the variable magnification optical system according to the eighteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 18.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a nineteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 19.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twentieth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system according to Example 20 1 is a perspective view of the front side of an imaging device according to an embodiment.
• FIG. 2 is a perspective view of the rear side of the imaging device according to the embodiment.
• FIG. 1 shows a cross-sectional view and a movement trajectory of the configuration of a variable magnification optical system according to one embodiment of the present disclosure.
• the upper row labeled "Wide” shows the wide-angle end state
• the lower row labeled “Tele” shows the telephoto end state.
• the example shown in FIG. 1 corresponds to the variable magnification optical system of Example 1 described below.
• FIG. 1 shows a state in which the lens is focused on an object at infinity, with the left side being the object side and the right side being the image side.
• FIG. 1 also shows the axial light beam wa and the light beam wb at the maximum half angle of view ⁇ w at the wide-angle end, as well as the axial light beam ta and the light beam tb at the maximum half angle of view ⁇ t at the telephoto end.
• the variable magnification optical system disclosed herein comprises, in order from the object side to the image side along the optical axis Z, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an intermediate group GM, and a final lens group GE having refractive power.
• the intermediate group GM comprises one or more and five or less lens groups.
• the aperture stop St is disposed between the lens surface of the second lens group G2 closest to the image and the lens surface of the final lens group GE closest to the object. This configuration allows the aperture unit to be made compact, which is advantageous for making the entire optical system more compact.
• the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the middle group GM changes, and the distance between the middle group GM and the final lens group GE changes.
• the middle group GM is made up of multiple lens groups, the distances between all of the adjacent lens groups in the middle group GM change when changing magnification. Changing the distances between multiple groups when changing magnification is advantageous in suppressing various aberrations throughout the entire range of magnification.
• the "first lens group G1", “second lens group G2", the “lens groups” included in the intermediate group GM, and the “final lens group GE” are components of a variable magnification optical system, and are portions including at least one lens separated by an air gap that changes when the magnification is changed.
• each lens group is moved or fixed, and the mutual spacing between the lenses in each lens group does not change.
• a group in which the spacing between adjacent groups changes when the magnification is changed, but the total spacing between adjacent lenses within the group does not change is defined as one lens group.
• the "lens group” may include components other than lenses that do not have refractive power, such as an aperture stop St.
• variable magnification optical system shown in FIG. 1 includes, in order from the object side to the image side, a first lens group G1,
• the intermediate lens group GM is made up of the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5.
• the intermediate lens group GM is made up of the third lens group G3 and the fourth lens group G4, and the final lens group GE is made up of the fifth lens group G5.
• each lens group in FIG. 1 is configured as follows.
• the first lens group G1 is made up of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 is made up of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 is made up of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 is made up of two lenses, lenses L41 to L42, from the object side to the image side.
• the fifth lens group G5 is made up of one lens, lens L51. Note that the aperture stop St in FIG. 1 does not indicate the shape or size, but rather the position in the optical axis direction.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim.
• the general movement trajectory of each lens group when changing magnification from the wide-angle end to the telephoto end is indicated by arrows between the upper and lower rows.
• the first lens group G1 includes, in succession from the object side to the image side, a first lens which is a negative lens and a second lens which is a positive lens.
• This configuration facilitates aberration correction within the first lens group G1, which is advantageous in suppressing aberration fluctuations during magnification. Furthermore, by locating the negative lens closest to the object side, it becomes easier to correct aberrations when the focal length at the wide-angle end is shortened.
• lens L11 corresponds to the first lens
• lens L12 corresponds to the second lens.
• the first lens group G1 can be configured to consist of, in order from the object side to the image side, a negative lens, a positive lens, and a positive lens.
• the second lens group G2 can be configured to consist of, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, and a negative lens.
• the intermediate group GM is composed of, from the object side to the image side, a lens group having positive refractive power and a lens group having negative refractive power, and the final lens group GE can be configured to have positive refractive power. This is advantageous in achieving both a simplified lens drive mechanism and high performance.
• the intermediate group GM includes an aperture stop St closest to the object.
• the aperture stop St and the first lens group G1 can be brought closer together, so the distance from the lens surface of the first lens group G1 closest to the object to the entrance pupil position can be shortened. This is advantageous for making the diameter of the first lens group G1 smaller.
• the final lens group GE may be configured to be fixed relative to the image plane Sim during zooming.
• the lens drive mechanism can be simplified.
• the final lens group GE may be configured to consist of a single positive aspheric lens. This is advantageous in achieving both a simplified lens drive mechanism and high performance.
• the variable magnification optical system of the present disclosure may be configured to include at least one focusing group that moves during magnification and focusing. Focusing is performed by moving the focusing group.
• the focusing group is made up of the fourth lens group G4.
• the brackets and right-pointing arrow below the fourth lens group G4 in FIG. 1 indicate that the fourth lens group G4 is a focusing group that moves toward the image side when focusing from an object at infinity to a closest object. Note that the fourth lens group G4 functions as a focusing group over the entire range of magnification, but in FIG. 1, in order to avoid cluttering the figure, the brackets and arrows indicating the focusing group are only attached to the lower diagram.
• One of the lens groups included in the intermediate group GM may be configured as a focusing group that moves during zooming and focusing. By placing the focusing group in the intermediate group GM, it is possible to make the focusing group smaller, which is advantageous for making the entire optical system smaller.
• the focusing group may be configured to consist of one positive lens and one negative lens.
• the number of lenses in the focusing group is reduced, which is advantageous in simplifying the mechanism for controlling the focusing group and also makes it easier to focus quickly.
• the focusing group may be configured to consist of one negative lens.
• the number of lenses in the focusing group can be further reduced, which is advantageous in simplifying the mechanism for controlling the focusing group and also facilitates faster focusing.
• the negative lens in the focusing group may be configured to be an aspheric lens. In this case, it is advantageous in terms of higher performance since aberration fluctuations during focusing can be suppressed.
• the focusing group may be configured to consist of one positive lens and two negative lenses. This is advantageous for high performance because it can suppress aberration fluctuations during focusing.
• the negative lens closest to the image side of the focusing group may be configured to be an aspheric lens. This is advantageous for high performance because it can suppress aberration fluctuations during focusing.
• the focusing group may be configured to consist of one negative lens and two positive lenses. This is advantageous for high performance because it can suppress aberration fluctuations during focusing.
• the positive lens closest to the image side of the focusing group may be configured to be an aspheric lens. This is advantageous for high performance because it can suppress aberration fluctuations during focusing.
• Two of the lens groups included in the intermediate group GM may be configured as focusing groups that move while changing the distance between them when varying magnification and when focusing.
• By placing the focusing group in the intermediate group GM it is possible to make the focusing group smaller, which is advantageous for making the entire optical system smaller. Furthermore, by employing a floating focus method to focus using two lens groups, aberration fluctuations during focusing can be effectively suppressed.
• the lens group located on the object side of the two focusing groups will be called the object-side focusing group
• the lens group located on the image side will be called the image-side focusing group.
• the object-side focusing group may be configured to consist of one negative lens and one positive lens, and the image-side focusing group may be configured to consist of one positive lens.
• the positive lens in the image-side focusing group may be configured to be an aspheric lens. In this case, it is advantageous for high performance to be achieved since it is possible to suppress aberration fluctuations during focusing.
• the object-side focusing group may be configured to be composed of one positive lens and one negative lens, and the image-side focusing group may be configured to be composed of one negative lens. In this case, it is advantageous for improving performance because it is possible to suppress aberration fluctuations during focusing.
• the negative lens of the image-side focusing group may be configured to be an aspheric lens. In this case, it is advantageous for improving performance because it is possible to suppress aberration fluctuations during focusing.
• variable magnification optical system of the present disclosure a preferred configuration for the conditional expressions of the variable magnification optical system of the present disclosure will be described. Note that in the following explanation of the conditional expressions, in order to avoid redundant explanations, the same symbols are used for elements with the same definitions and some of the duplicated explanations of the symbols will be omitted. In addition, in the following, in order to avoid redundant explanations, the "variable magnification optical system of the present disclosure” will also be simply referred to as the "variable magnification optical system".
• variable magnification optical system satisfies the following conditional expression (1).
• the distance on the optical axis from the object side surface of the first lens to the aperture stop St in a state where an object at infinity is focused at the wide-angle end is DDL1STw.
• the sum of the distance on the optical axis from the object side surface of the first lens to the lens surface closest to the image side of the final lens group GE in a state where an object at infinity is focused at the wide-angle end and the back focus of the entire system in air conversion distance is TLw.
• the "back focus of the entire system in air conversion distance” is the air conversion distance on the optical axis from the lens surface closest to the image side of the entire system to the image surface Sim.
• TLw is the total length in a state where an object at infinity is focused at the wide-angle end.
• variable magnification optical system it is more preferable for the variable magnification optical system to satisfy the following conditional expression (1-1), more preferably the following conditional expression (1-2), even more preferably the following conditional expression (1-3), and even more preferably the following conditional expression (1-4).
• conditional expression (1-1) more preferably the following conditional expression (1-2), even more preferably the following conditional expression (1-3), and even more preferably the following conditional expression (1-4).
• 0.05 ⁇ DDL1STw/TLw ⁇ 0.46 (1-1) 0.1 ⁇ DDL1STw/TLw ⁇ 0.43 (1-2) 0.15 ⁇ DDL1STw/TLw ⁇ 0.41 (1-3) 0.2 ⁇ DDL1STw/TLw ⁇ 0.39 (1-4)
• Figure 2 shows a cross-sectional view of the variable magnification optical system of Figure 1, and shows the above-mentioned distance DDL1STw and total length TLw in this variable magnification optical system as an example.
• the upper row labeled “Wide” shows the wide-angle end state
• the lower row labeled “Tele” shows the telephoto end state.
• variable magnification optical system satisfies the following conditional expression (2).
• the maximum F-number when focused on an object at infinity at the telephoto end is Fnot.
• the focal length of the entire system when focused on an object at infinity at the telephoto end is ft.
• the focal length of the entire system when focused on an object at infinity at the wide-angle end is fw.
• conditional expression (2) By making the corresponding value of conditional expression (2) not equal to or more than the upper limit, it is easy to maintain a small F-number at the telephoto end, and it is advantageous to obtain sufficient brightness at the telephoto end.
• the variable magnification optical system satisfies the following conditional expression (2-1), more preferably satisfies the following conditional expression (2-2), even more preferably satisfies the following conditional expression (2-3), and even more preferably satisfies the following conditional expression (2-4).
• variable magnification optical system satisfies the following conditional expression (3).
• the back focus of the entire system at the air equivalent distance at the wide-angle end is Bfw.
• the maximum half angle of view in the state of focusing on an object at infinity at the telephoto end is ⁇ t.
• tan is the tangent.
• the above back focus Bfw is shown in FIG. 2.
• variable magnification optical system satisfies the following conditional expression (3-1), more preferably satisfies the following conditional expression (3-2), even more preferably satisfies the following conditional expression (3-3), and even more preferably satisfies the following conditional expression (3-4).
• 3-1 the following conditional expression
• 3-2 the following conditional expression
• 3-3 the following conditional expression
• 3-4 the following conditional expression
• variable magnification optical system satisfies the following conditional expression (4).
• conditional expression (4) By making sure that the corresponding value of conditional expression (4) is not equal to or less than the lower limit, it is advantageous for suppressing various aberrations.
• the corresponding value of conditional expression (4) By making sure that the corresponding value of conditional expression (4) is not equal to or greater than the upper limit, it is easy to obtain a wide angle of view at the wide-angle end.
• variable magnification optical system satisfies the following conditional expression (4-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (4-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (4-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (4-4).
• variable magnification optical system satisfies the following conditional expression (5).
• the focal length of the first lens group G1 is f1.
• the composite focal length of the optical system from the first lens to the aperture stop St in a state where the optical system is focused on an object at infinity at the wide-angle end is fL1STw.
• conditional expression (5) By making the corresponding value of conditional expression (5) not equal to or more than the upper limit, the refractive power of the first lens group G1 does not become too strong, so that the suppression of aberration fluctuation during magnification change can be easily achieved.
• the variable magnification optical system satisfies the following conditional expression (5-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (5-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (5-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (5-4).
• variable magnification optical system satisfies the following conditional expression (6).
• conditional expression (6) By making the corresponding value of conditional expression (6) not equal to or less than the lower limit, the refractive power of the negative lens closest to the object side does not become too strong, so that it is easy to suppress high-order aberrations at the telephoto end. Or, the refractive power of the first lens group G1 does not become too weak, so that it is easy to miniaturize the first lens group G1.
• "high order” regarding aberrations means fifth order or more.
• conditional expression (6) By making the corresponding value of conditional expression (6) not equal to or more than the upper limit, the refractive power of the first lens group G1 does not become too strong, so that it is easy to suppress aberration fluctuations during magnification. Or, the refractive power of the negative lens closest to the object side does not become too weak, so that it is easy to suppress axial chromatic aberrations at the telephoto end.
• variable magnification optical system satisfies the following conditional formula (6-1), it is even more preferable that it satisfies the following conditional formula (6-2), it is even more preferable that it satisfies the following conditional formula (6-3), and it is even more preferable that it satisfies the following conditional formula (6-4).
• conditional formula (6-1) it is even more preferable that it satisfies the following conditional formula (6-2)
• 6-3 satisfies the following conditional formula (6-4)
• variable magnification optical system satisfies the following conditional expression (7).
• conditional expression (7) By making sure that the corresponding value of conditional expression (7) is not equal to or less than the lower limit, it is advantageous for suppressing various aberrations.
• the corresponding value of conditional expression (7) By making sure that the corresponding value of conditional expression (7) is not equal to or greater than the upper limit, it is easy to obtain a wide angle of view at the wide-angle end.
• variable magnification optical system satisfies the following conditional expression (7-1), it is even more preferable that it satisfies the following conditional expression (7-2), it is even more preferable that it satisfies the following conditional expression (7-3), and it is even more preferable that it satisfies the following conditional expression (7-4).
• ⁇ 1.4 ⁇ fw/fL1STw ⁇ 0.3 (7) ⁇ 1.3 ⁇ fw/fL1STw ⁇ 0.4 (7-1) -1.2 ⁇ fw/fL1STw ⁇ -0.5 (7-2) ⁇ 1.1 ⁇ fw/fL1STw ⁇ 0.6 (7-3) -1 ⁇ fw/fL1STw ⁇ -0.7 (7-4)
• variable magnification optical system satisfies the following conditional expression (8).
• conditional expression (8) By making sure that the corresponding value of conditional expression (8) is not equal to or lower than the lower limit, it becomes easy to suppress various aberrations throughout the entire range of magnification.
• the corresponding value of conditional expression (8) By making sure that the corresponding value of conditional expression (8) is not equal to or higher than the upper limit, it becomes advantageous for miniaturization of the entire optical system.
• variable magnification optical system satisfies the following conditional expression (8-1), it is even more preferable that it satisfies the following conditional expression (8-2), it is even more preferable that it satisfies the following conditional expression (8-3), and it is even more preferable that it satisfies the following conditional expression (8-4).
• variable magnification optical system satisfies the following conditional expression (9).
• the lateral magnification of the second lens group G2 in a state in which an object at infinity is focused at the telephoto end is ⁇ 2t.
• the lateral magnification of the second lens group G2 in a state in which an object at infinity is focused at the wide-angle end is ⁇ 2w.
• variable magnification optical system satisfies the following conditional expression (9-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (9-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (9-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (9-4).
• 1.1 ⁇ ⁇ 2t / ⁇ 2w ⁇ 3 (9) 1.2 ⁇ 2t/ ⁇ 2w ⁇ 2.7 (9-1) 1.2 ⁇ 2t/ ⁇ 2w ⁇ 2.4 (9-2) 1.3 ⁇ 2t/ ⁇ 2w ⁇ 2.1 (9-3) 1.3 ⁇ 2t/ ⁇ 2w ⁇ 1.9 (9-4)
• variable magnification optical system satisfies the following conditional expression (10).
• the distance on the optical axis between the first lens group G1 and the second lens group G2 in a state where the lens is focused on an object at infinity at the wide-angle end is DDG12w.
• the distance on the optical axis between the first lens group G1 and the second lens group G2 in a state where the lens is focused on an object at infinity at the telephoto end is DDG12t.
• TLt is the total length in a state where the lens is focused on an object at infinity at the telephoto end.
• FIG. 2 shows the above-mentioned distance DDG12w, distance DDG12t, and total length TLt.
• conditional expression (10) By making the corresponding value of conditional expression (10) not equal to or greater than the upper limit, it is advantageous for suppressing the change in the center of gravity position during zooming. Also, it is advantageous for suppressing distortion during zooming. In order to obtain better characteristics, it is more preferable for the zoom optical system to satisfy the following conditional expression (10-1), more preferably the following conditional expression (10-2), even more preferably the following conditional expression (10-3), and even more preferably the following conditional expression (10-4).
• variable magnification optical system satisfies the following conditional expression (11).
• conditional expression (11) By making the corresponding value of conditional expression (11) not equal to or less than the lower limit, the movable range of the second lens group G2 during magnification is not too short, so that a high variable magnification ratio can be easily achieved.
• the refractive power of the first lens group G1 is not too weak, so that both compactness and a high variable magnification ratio can be easily achieved.
• conditional expression (11) By making the corresponding value of conditional expression (11) not equal to or more than the upper limit, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position is not too long, so that the diameter of the first lens group G1 can be suppressed from being increased, so that compactness can be easily achieved.
• the refractive power of the first lens group G1 is not too strong, so that high performance can be easily achieved.
• variable magnification optical system satisfies the following conditional expression (11-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (11-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (11-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (11-4).
• variable magnification optical system When the maximum half angle of view in a state where an object at infinity is focused at the wide-angle end is ⁇ w, it is preferable that the variable magnification optical system satisfies the following conditional expression (12).
• conditional expression (12) By making the corresponding value of conditional expression (12) not equal to or less than the lower limit, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position does not become too short, so that it is easy to suppress aberration fluctuations during magnification.
• conditional expression (12) By making the corresponding value of conditional expression (12) not equal to or more than the upper limit, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position does not become too long, so that it is possible to suppress an increase in the diameter of the first lens group G1, so that it is easy to reduce the size.
• the variable magnification optical system satisfies the following conditional expression (12-1), it is even more preferable that it satisfies the following conditional expression (12-2), it is even more preferable that it satisfies the following conditional expression (12-3), and it is even more preferable that it satisfies the following conditional expression (12-4).
• variable magnification optical system satisfies the following conditional expression (13).
• conditional expression (13) By making sure that the corresponding value of conditional expression (13) is not equal to or less than the lower limit, it becomes easy to suppress various aberrations at the wide-angle end.
• conditional expression (13) By making sure that the corresponding value of conditional expression (13) is not equal to or greater than the upper limit, it becomes easy to shorten the overall length at the wide-angle end.
• variable magnification optical system satisfies the following conditional expression (13-1), it is even more preferable that it satisfies the following conditional expression (13-2), it is even more preferable that it satisfies the following conditional expression (13-3), and it is even more preferable that it satisfies the following conditional expression (13-4).
• 13-1 the variable magnification optical system satisfies the following conditional expression
• (13-2) 3.5 ⁇ TLw/fw ⁇ 7.5
• 13-3) 3.5 ⁇ TLw/fw ⁇ 7 (13-2) 4 ⁇ TLw/fw ⁇ 6.5 (13-3) 4 ⁇ TLw/fw ⁇ 6 (13-4)
• variable magnification optical system satisfies the following conditional expression (14).
• conditional expression (14) By making sure that the corresponding value of conditional expression (14) is not equal to or lower than the lower limit, it becomes easy to suppress various aberrations at the telephoto end.
• conditional expression (14) By making sure that the corresponding value of conditional expression (14) is not equal to or higher than the upper limit, it becomes easy to shorten the overall length at the telephoto end.
• variable magnification optical system satisfies the following conditional expression (14-1), it is even more preferable that it satisfies the following conditional expression (14-2), it is even more preferable that it satisfies the following conditional expression (14-3), and it is even more preferable that it satisfies the following conditional expression (14-4).
• 1.5 ⁇ TLt/ft ⁇ 3 (14) 1.65 ⁇ TLt/ft ⁇ 2.85 (14-1) 1.8 ⁇ TLt/ft ⁇ 2.7 (14-2) 1.95 ⁇ TLt/ft ⁇ 2.7 (14-3) 2.05 ⁇ TLt/ft ⁇ 2.55 (14-4)
• variable magnification optical system satisfies the following conditional expression (15).
• conditional expression (15) By making the corresponding value of conditional expression (15) not equal to or less than the lower limit, the axial light beam ta can be gradually converged toward the image surface Sim at the telephoto end, so that the axial chromatic aberration that occurs when the light beam is converged can be suppressed.
• the corresponding value of conditional expression (15) By making the corresponding value of conditional expression (15) not equal to or greater than the upper limit, it becomes easy to shorten the overall length at the telephoto end.
• variable magnification optical system satisfies the following conditional expression (15-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (15-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (15-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (15-4).
• variable magnification optical system satisfies the following conditional expression (16).
• conditional expression (16) By making the corresponding value of conditional expression (16) not equal to or less than the lower limit, the refractive power of the first lens group G1 does not become too strong, and thus it becomes easy to suppress aberration fluctuations during magnification.
• conditional expression (16) By making the corresponding value of conditional expression (16) not equal to or more than the upper limit, the refractive power of the first lens group G1 does not become too weak, and thus it becomes easy to make the first lens group G1 compact.
• variable magnification optical system satisfies the following conditional expression (16-1), it is even more preferable that it satisfies the following conditional expression (16-2), it is even more preferable that it satisfies the following conditional expression (16-3), and it is even more preferable that it satisfies the following conditional expression (16-4).
• variable magnification optical system satisfies the following conditional expression (17).
• conditional expression (17) By making the corresponding value of conditional expression (17) not equal to or less than the lower limit, the refractive power of the second lens group G2 does not become too weak, so that it is easy to suppress the movement amount of the second lens group G2 during variable magnification.
• conditional expression (17) By making the corresponding value of conditional expression (17) not equal to or more than the upper limit, the refractive power of the first lens group G1 does not become too weak, so that it is easy to suppress the increase in size of the first lens group G1.
• variable magnification optical system satisfies the following conditional expression (17-1), it is even more preferable that it satisfies the following conditional expression (17-2), it is even more preferable that it satisfies the following conditional expression (17-3), and it is even more preferable that it satisfies the following conditional expression (17-4).
• 3 ⁇ f1/(-f2) ⁇ 9 (17) 3.5 ⁇ f1/(-f2) ⁇ 8.5 (17-1) 4 ⁇ f1 / (-f2) ⁇ 8 (17-2) 4 ⁇ f1 / (-f2) ⁇ 7.5 (17-3) 4.5 ⁇ f1 / (-f2) ⁇ 7 (17-4)
• variable magnification optical system satisfies the following conditional expression (18).
• conditional expression (18) By making sure that the corresponding value of conditional expression (18) is not equal to or lower than the lower limit, it is advantageous for improving performance.
• the refractive power of the first lens group G1 does not become too weak, making it easy to reduce the size of the first lens group G1.
• variable magnification optical system satisfies the following conditional expression (18-1), it is even more preferable that it satisfies the following conditional expression (18-2), it is even more preferable that it satisfies the following conditional expression (18-3), and it is even more preferable that it satisfies the following conditional expression (18-4).
• conditional expression (18-1) 2.5 ⁇ f1/(ft/Fnot) ⁇ 6.5 (18-1)
• 3 ⁇ f1/(ft/Fnot) ⁇ 6.5 (18-2) 3.5 ⁇ f1/(ft/Fnot) ⁇ 6 (18-3) 4 ⁇ f1/(ft/Fnot) ⁇ 6 (18-4)
• variable magnification optical system satisfies the following conditional expression (19).
• conditional expression (19) By making the corresponding value of conditional expression (19) not equal to or less than the lower limit, the refractive power of the first lens group G1 does not become too strong, which makes it easy to suppress aberration fluctuations during magnification.
• conditional expression (19) By making the corresponding value of conditional expression (19) not equal to or more than the upper limit, the refractive power of the first lens group G1 does not become too weak, which is advantageous for size reduction.
• variable magnification optical system satisfies the following conditional expression (19-1), it is even more preferable that it satisfies the following conditional expression (19-2), it is even more preferable that it satisfies the following conditional expression (19-3), and it is even more preferable that it satisfies the following conditional expression (19-4).
• variable magnification optical system satisfies the following conditional expression (20).
• Denw is the distance on the optical axis from the object side surface of the first lens to the paraxial entrance pupil position Penw in a state where an object at infinity is focused at the wide-angle end.
• FIG. 2 shows the above distance Denw and the paraxial entrance pupil position Penw.
• conditional expression (20) By making the corresponding value of conditional expression (20) not equal to or more than the upper limit, the distance from the object side surface of the first lens on the wide-angle side to the entrance pupil position does not become too long, making it possible to suppress an increase in the diameter of the first lens group G1, and thus facilitating miniaturization.
• the variable magnification optical system satisfies the following conditional formula (20-1), it is even more preferable that it satisfies the following conditional formula (20-2), it is even more preferable that it satisfies the following conditional formula (20-3), and it is even more preferable that it satisfies the following conditional formula (20-4).
• variable magnification optical system satisfies the following conditional expression (21).
• conditional expression (21) By making the corresponding value of conditional expression (21) not equal to or less than the lower limit, the distance from the object-side surface of the first lens to the entrance pupil position does not become too short, so that it is easy to suppress aberration fluctuations during magnification.
• conditional expression (21) By making the corresponding value of conditional expression (21) not equal to or more than the upper limit, the distance from the object-side surface of the first lens to the entrance pupil position does not become too long, so that it is possible to suppress an increase in the diameter of the first lens group G1, so that it is easy to reduce the size.
• variable magnification optical system satisfies the following conditional expression (21-1), it is even more preferable that it satisfies the following conditional expression (21-2), it is even more preferable that it satisfies the following conditional expression (21-3), and it is even more preferable that it satisfies the following conditional expression (21-4).
• variable magnification optical system satisfies the following conditional expression (22).
• conditional expression (22) By ensuring that the corresponding value of conditional expression (22) is not equal to or less than the lower limit, it is advantageous for ensuring the strength of the first lens.
• the corresponding value of conditional expression (22) By ensuring that the corresponding value of conditional expression (22) is not equal to or greater than the upper limit, it is advantageous for reducing the weight of the first lens group G1.
• variable magnification optical system satisfies the following conditional expression (22-1), it is even more preferable that it satisfies the following conditional expression (22-2), it is even more preferable that it satisfies the following conditional expression (22-3), and it is even more preferable that it satisfies the following conditional expression (22-4).
• variable magnification optical system satisfies the following conditional expression (23).
• the distance on the optical axis from the image surface Sim to the paraxial exit pupil position Pexw in a state where an object at infinity is focused at the wide-angle end is Dexw.
• the sign of Dexw is positive for the distance on the image side and negative for the distance on the object side with respect to the image surface Sim.
• Dexw is calculated using the air equivalent distance for that optical member.
• FIG. 2 shows the above-mentioned distance Dexw and the paraxial exit pupil position Pexw.
• variable magnification optical system satisfies the following conditional formula (23-1), it is even more preferable that it satisfies the following conditional formula (23-2), it is even more preferable that it satisfies the following conditional formula (23-3), and it is even more preferable that it satisfies the following conditional formula (23-4).
• conditional formula (23-1) it is even more preferable that it satisfies the following conditional formula (23-2), it is even more preferable that it satisfies the following conditional formula (23-3), and it is even more preferable that it satisfies the following conditional formula (23-4).
• variable magnification optical system satisfies the following conditional expression (24).
• the effective diameter of the object side surface of the first lens is EDf.
• the effective diameter of the lens surface of the final lens group GE closest to the image side is EDr.
• conditional expression (24) By making the corresponding value of conditional expression (24) not equal to or more than the upper limit, the diameter of the first lens does not become too large, so that it is easy to reduce the size.
• the variable magnification optical system satisfies the following conditional expression (24-1), it is even more preferable that it satisfies the following conditional expression (24-2), it is even more preferable that it satisfies the following conditional expression (24-3), and it is even more preferable that it satisfies the following conditional expression (24-4).
• the "effective diameter" of a lens surface is defined as twice the distance from the intersection of the outermost ray and the lens surface to the optical axis Z, among the rays that enter the lens surface from the object side and emerge to the image side.
• “Outside” here refers to the radially outward direction centered on the optical axis Z, in other words, the side away from the optical axis Z.
• the “outermost ray” is determined taking into account the entire range of magnification.
• FIG. 3 shows an example of the effective diameter ED.
• the left side is the object side
• the right side is the image side.
• FIG. 3 shows an on-axis light beam Xa and an off-axis light beam Xb passing through the lens Lx.
• the upper ray of the off-axis light beam Xb, ray Xb1 is the ray that passes through the outermost part. Therefore, in the example of FIG. 3, the effective diameter ED of the object-side surface of the lens Lx is twice the distance from the intersection of the object-side surface of the lens Lx and ray Xb1 to the optical axis Z.
• the position of the intersection of the outermost ray and the lens surface is the position Px of the maximum effective diameter.
• the upper ray of the off-axis light beam Xb is the ray that passes through the outermost part, but which ray passes through the outermost part varies depending on the optical system.
• variable magnification optical system satisfies the following conditional expression (25).
• conditional expression (25) By making sure that the corresponding value of conditional expression (25) is not equal to or less than the lower limit, it is advantageous for shortening the overall length. By making sure that the corresponding value of conditional expression (25) is not equal to or greater than the upper limit, it is easy to reduce the diameter of the first lens.
• variable magnification optical system satisfies the following conditional expression (25-1), it is even more preferable that it satisfies the following conditional expression (25-2), it is even more preferable that it satisfies the following conditional expression (25-3), and it is even more preferable that it satisfies the following conditional expression (25-4).
• 0.35 ⁇ EDf/TLw ⁇ 0.65 (25) 0.38 ⁇ EDf/TLw ⁇ 0.62 (25-1) 0.41 ⁇ EDf/TLw ⁇ 0.59 (25-2) 0.41 ⁇ EDf/TLw ⁇ 0.56 (25-3) 0.44 ⁇ EDf/TLw ⁇ 0.53 (25-4)
• variable magnification optical system satisfies the following conditional expression (26).
• conditional expression (26) By making sure that the corresponding value of conditional expression (26) is not equal to or less than the lower limit, the variable magnification ratio does not become too low, and thus a useful value as a variable magnification optical system can be obtained.
• the variable magnification ratio does not become too high, and thus it is advantageous for miniaturization.
• variable magnification optical system satisfies the following conditional expression (26-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (26-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (26-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (26-4).
• 2.2 ⁇ ft/fw ⁇ 4.8 (26) 2.35 ⁇ ft/fw ⁇ 4.4 (26-1) 2.35 ⁇ ft/fw ⁇ 4 (26-1) 2.5 ⁇ ft/fw ⁇ 3.6 (26-1) 2.5 ⁇ ft/fw ⁇ 3.2 (26-1)
• the variable magnification optical system satisfies the following conditional expression (27).
• conditional expression (27) By making the corresponding value of conditional expression (27) not smaller than the lower limit, the absolute value of the radius of curvature of the first lens does not become too small in order to ensure the refractive power of the first lens necessary to correct the aberration generated by the positive lens constituting the first lens group G1. As a result, it is possible to suppress an increase in high-order aberration of the spherical aberration at the telephoto end, which is advantageous for improving performance.
• conditional expression (27) by making the corresponding value of conditional expression (27) not smaller than the lower limit, the refractive power of the first lens does not become too weak and the outer diameter does not become too large, so that the refractive power of the positive lens of the first lens group G1 does not become too weak and the outer diameter does not become too large. This makes it easy to make the first lens group G1 compact.
• the upper limit of conditional expression (27) since the specific gravity of an optical material generally increases and the Abbe number decreases as the refractive index increases, by making the corresponding value of conditional expression (27) not equal to or greater than the upper limit, the increase in the weight of the first lens having a large lens diameter can be suppressed, making it easier to reduce the weight.
• variable magnification optical system it becomes easier to correct chromatic aberration of magnification at the wide-angle end.
• variable magnification optical system it is more preferable for the variable magnification optical system to satisfy the following conditional expression (27-1), more preferably the following conditional expression (27-2), more preferably the following conditional expression (27-3), and even more preferably the following conditional expression (27-4).
• 1.8 ⁇ NdL1 ⁇ 2.01 (27) 1.8 ⁇ NdL1 ⁇ 1.96 (27-1) 1.8 ⁇ NdL1 ⁇ 1.91 (27-2) 1.84 ⁇ NdL1 ⁇ 1.96 (27-3) 1.84 ⁇ NdL1 ⁇ 1.91 (27-4)
• variable magnification optical system satisfies the following conditional expression (28).
• conditional expression (28) By making the corresponding value of conditional expression (28) not equal to or less than the lower limit, it is possible to suppress overcorrection of the axial chromatic aberration at the telephoto end. Or, since the difference in the Abbe numbers between the positive lens and the negative lens constituting the first lens group G1 does not become too large, the refractive power of the first lens does not become too weak. As a result, it is easy to correct the chromatic aberration of magnification at the wide-angle end.
• conditional expression (28) By making the corresponding value of conditional expression (28) not equal to or more than the upper limit, it is possible to suppress undercorrection of the axial chromatic aberration at the telephoto end. Or, since the difference in the Abbe numbers between the positive lens and the negative lens constituting the first lens group G1 does not become too small, the refractive power of each lens constituting the first lens group G1 does not become too strong. As a result, it is possible to suppress an increase in the high-order aberration of the spherical aberration at the telephoto end, and it is easy to improve the performance.
• variable magnification optical system satisfies the following conditional formula (28-1), it is even more preferable that it satisfies the following conditional formula (28-2), it is even more preferable that it satisfies the following conditional formula (28-3), and it is even more preferable that it satisfies the following conditional formula (28-4).
• 15 ⁇ dL1 ⁇ 45 (28) 15 ⁇ dL1 ⁇ 40 (28-1) 15 ⁇ dL1 ⁇ 36 (28-2) 18 ⁇ dL1 ⁇ 36 (28-3) 20 ⁇ dL1 ⁇ 36 (28-4)
• variable magnification optical system satisfies the following conditional expression (29).
• conditional expression (29) By making the corresponding value of conditional expression (29) not equal to or less than the lower limit, a material other than a material with a low refractive index and a low Abbe number can be selected, so that the correction of chromatic aberration of magnification at the wide-angle end is easy.
• a material other than a material with a high refractive index and a high Abbe number can be selected, so that a material with a low specific gravity can be selected, so that weight reduction is easy.
• variable magnification optical system satisfies the following conditional expression (29-1), more preferably satisfies the following conditional expression (29-2), more preferably satisfies the following conditional expression (29-3), and even more preferably satisfies the following conditional expression (29-4).
• variable magnification optical system simultaneously satisfies conditional expressions (27), (28), and (29). It is even more preferable that the variable magnification optical system simultaneously satisfies conditional expressions (27), (28), and (29), and furthermore satisfies at least one of conditional expressions (27-1), (27-2), (27-3), (27-4), (28-1), (28-2), (28-3), (28-4), (29-1), (29-2), (29-3), and (29-4).
• the variable magnification optical system satisfies the following conditional expression (30).
• the corresponding value of conditional expression (30) not smaller than the lower limit, the absolute value of the radius of curvature of the positive lens constituting the first lens group G1 is not reduced in order to ensure the positive refractive power required for the miniaturization of the first lens group G1.
• the increase in the high-order aberration of the spherical aberration at the telephoto end can be suppressed, so that it is easy to improve the performance. Or, it is easy to miniaturize the first lens group G1.
• conditional expression (30) since the specific gravity of an optical material generally increases as the refractive index increases, by making the corresponding value of conditional expression (30) not larger than the upper limit, it is possible to suppress the increase in the weight of the lens, so that it is easy to reduce the weight.
• the variable magnification optical system satisfies the following conditional formula (30-1), it is even more preferable that it satisfies the following conditional formula (30-2), it is even more preferable that it satisfies the following conditional formula (30-3), and it is even more preferable that it satisfies the following conditional formula (30-4).
• the variable magnification optical system satisfies the following conditional expression (31).
• conditional expression (31) By making the corresponding value of conditional expression (31) not equal to or less than the lower limit, it is possible to suppress undercorrection of axial chromatic aberration at the telephoto end. Or, since the difference in Abbe number between the positive lens and the negative lens constituting the first lens group G1 does not become too small, the refractive power of each lens constituting the first lens group G1 does not become too strong. As a result, it is possible to suppress an increase in high-order aberration of spherical aberration at the telephoto end, and it is easy to improve performance.
• conditional expression (31) By making the corresponding value of conditional expression (31) not equal to or more than the upper limit, it is possible to suppress overcorrection of axial chromatic aberration at the telephoto end. Or, since the difference in Abbe number between the positive lens and the negative lens constituting the first lens group G1 does not become too large, the refractive power of the first lens does not become too weak. As a result, it is easy to correct chromatic aberration of magnification at the wide-angle end.
• variable magnification optical system satisfies the following conditional formula (31-1), it is even more preferable that it satisfies the following conditional formula (31-2), it is even more preferable that it satisfies the following conditional formula (31-3), and it is even more preferable that it satisfies the following conditional formula (31-4).
• 45 ⁇ dL2 ⁇ 96 (31) 45 ⁇ dL2 ⁇ 82 (31-1) 45 ⁇ dL2 ⁇ 77 (31-2) 45 ⁇ dL2 ⁇ 71 (31-3) 49 ⁇ dL2 ⁇ 71 (31-4)
• variable magnification optical system satisfies the following conditional expression (32).
• conditional expression (32) By making the corresponding value of conditional expression (32) not equal to or less than the lower limit, a material other than a material with a low refractive index and a low Abbe number can be selected, so that an increase in high-order aberration of the spherical aberration at the telephoto end can be suppressed, and this facilitates high performance.
• conditional expression (32) By making the corresponding value of conditional expression (32) not equal to or more than the upper limit, a material other than a material with a high refractive index and a high Abbe number can be selected, so that a material with a low specific gravity can be selected, and this facilitates weight reduction. Alternatively, it is possible to suppress overcorrection of the axial chromatic aberration at the telephoto end.
• variable magnification optical system satisfies the following conditional expression (32-1), it is even more preferable that it satisfies the following conditional expression (32-2), it is even more preferable that it satisfies the following conditional expression (32-3), and it is even more preferable that it satisfies the following conditional expression (32-4).
• variable magnification optical system simultaneously satisfies conditional expressions (30), (31), and (32). It is even more preferable that the variable magnification optical system simultaneously satisfies conditional expressions (30), (31), and (32), and furthermore satisfies at least one of conditional expressions (30-1), (30-2), (30-3), (30-4), (31-1), (31-2), (31-3), (31-4), (32-1), (32-2), (32-3), and (32-4).
• the variable magnification optical system preferably satisfies the following conditional expression (33).
• the focal length of the focusing group with the smallest absolute focal length value among the focusing groups included in the variable magnification optical system is designated as ffoc.
• the focal length of the middle group GM in a state where the lens is focused on an object at infinity at the telephoto end is designated as fMt.
• conditional expression (33) By making the corresponding value of conditional expression (33) not equal to or more than the upper limit, the refractive power of the focusing group does not become too weak, and thus insufficient aberration correction during focusing can be suppressed.
• the variable magnification optical system satisfies the following conditional formula (33-1), it is even more preferable that it satisfies the following conditional formula (33-2), it is even more preferable that it satisfies the following conditional formula (33-3), and it is even more preferable that it satisfies the following conditional formula (33-4).
• the variable magnification optical system preferably satisfies the following conditional expression (34).
• the lateral magnification of the focusing group with the largest absolute value of focal length among the focusing groups included in the variable magnification optical system when focused on an object at infinity at the telephoto end is ⁇ ft.
• the composite lateral magnification of all lenses on the image side of the focusing group with the largest absolute value of focal length when focused on an object at infinity at the telephoto end is ⁇ fRt.
• conditional expression (34) By making the corresponding value of conditional expression (34) not equal to or less than the lower limit, the ratio of the image plane movement amount to the unit movement amount of the focusing group does not become too small, so that the movement amount of the focusing group during focusing does not become too large, which is advantageous for achieving both high performance and compactness.
• conditional expression (34) By making the corresponding value of conditional expression (34) not equal to or more than the upper limit, the ratio of the image plane movement amount to the unit movement amount of the focusing group does not become too large, which is advantageous for achieving both manufacturability and compactness.
• variable magnification optical system satisfies the following conditional formula (34-1), it is even more preferable that it satisfies the following conditional formula (34-2), it is even more preferable that it satisfies the following conditional formula (34-3), and it is even more preferable that it satisfies the following conditional formula (34-4).
• the variable magnification optical system satisfies the following conditional expression (35) for this aspheric lens.
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcnf.
• the paraxial radius of curvature of the image side surface of the aspheric lens is Rcnr.
• the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is Rynf.
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rynr.
• conditional expression (35) By making the corresponding value of conditional expression (35) not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion aberration.
• conditional expression (35) By making the corresponding value of conditional expression (35) not equal to or more than the upper limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting field curvature and astigmatism caused by off-axis light rays on the peripheral side of the lens.
• variable magnification optical system satisfies the following conditional formula (35-1), it is even more preferable that it satisfies the following conditional formula (35-2), it is even more preferable that it satisfies the following conditional formula (35-3), and it is even more preferable that it satisfies the following conditional formula (35-4).
• the variable magnification optical system satisfies the following conditional expression (36) for this aspheric lens.
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcpf.
• the paraxial radius of curvature of the image side surface of the aspheric lens is Rcpr.
• the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is Rypf.
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rypr.
• conditional expression (36) By making the corresponding value of conditional expression (36) not equal to or less than the lower limit, the refractive power of the lens on the peripheral side is not too weak, which is advantageous for correcting the curvature of field and astigmatism caused by off-axis rays on the peripheral side of the lens.
• the refractive power of the lens on the peripheral side is not too strong, which is advantageous for suppressing distortion aberration.
• variable magnification optical system satisfies the following conditional formula (36-1), it is even more preferable that it satisfies the following conditional formula (36-2), it is even more preferable that it satisfies the following conditional formula (36-3), and it is even more preferable that it satisfies the following conditional formula (36-4).
• the variable magnification optical system satisfies the following conditional expression (37) for this aspheric lens.
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcsnf.
• the paraxial radius of curvature of the image side surface of the aspheric lens is Rcsnr.
• the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is Rysnf.
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rysnr.
• conditional expression (37) By making the corresponding value of conditional expression (37) not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion aberration.
• conditional expression (37) By making the corresponding value of conditional expression (37) not equal to or more than the upper limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting field curvature and astigmatism caused by off-axis light rays on the peripheral side of the lens.
• variable magnification optical system satisfies the following conditional formula (37-1), it is even more preferable that it satisfies the following conditional formula (37-2), it is even more preferable that it satisfies the following conditional formula (37-3), and it is even more preferable that it satisfies the following conditional formula (37-4).
• the variable magnification optical system satisfies the following conditional expression (38) for this aspheric lens.
• the paraxial radius of curvature of the object-side surface of the aspheric lens is Rcipf.
• the paraxial radius of curvature of the image-side surface of the aspheric lens is Rcipr.
• the radius of curvature at the position of the maximum effective diameter of the object-side surface of the aspheric lens is Ryipf.
• the radius of curvature at the position of the maximum effective diameter of the image-side surface of the aspheric lens is Ryipr.
• conditional expression (38) By making the corresponding value of conditional expression (38) not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion aberration.
• conditional expression (38) By making the corresponding value of conditional expression (38) not equal to or more than the upper limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting field curvature and astigmatism caused by off-axis light rays on the peripheral side of the lens.
• variable magnification optical system satisfies the following conditional formula (38-1), it is even more preferable that it satisfies the following conditional formula (38-2), it is even more preferable that it satisfies the following conditional formula (38-3), and it is even more preferable that it satisfies the following conditional formula (38-4).
• the variable magnification optical system satisfies the following conditional expression (39) for this aspheric lens.
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcinf.
• the paraxial radius of curvature of the image side surface of the aspheric lens is Rcinr.
• the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is Ryinf.
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Ryinr.
• conditional expression (39) By making the corresponding value of conditional expression (39) not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion aberration.
• the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting field curvature and astigmatism caused by off-axis light rays on the peripheral side of the lens.
• variable magnification optical system satisfies the following conditional formula (39-1), it is even more preferable that it satisfies the following conditional formula (39-2), it is even more preferable that it satisfies the following conditional formula (39-3), and it is even more preferable that it satisfies the following conditional formula (39-4).
• the variable magnification optical system satisfies the following conditional expression (40) for this aspherical lens.
• the paraxial radius of curvature of the object-side surface of the aspherical lens is RcEpf.
• the paraxial radius of curvature of the image-side surface of the aspherical lens is RcEpr.
• the radius of curvature at the position of the maximum effective diameter of the object-side surface of the aspherical lens is RyEpf.
• the radius of curvature at the position of the maximum effective diameter of the image-side surface of the aspherical lens is RyEpr.
• conditional expression (40) By making the corresponding value of conditional expression (40) not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion aberration. By making the corresponding value of conditional expression (40) not equal to or more than the upper limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting field curvature and astigmatism caused by off-axis light rays on the peripheral side of the lens.
• variable magnification optical system satisfies the following conditional formula (40-1), it is even more preferable that it satisfies the following conditional formula (40-2), it is even more preferable that it satisfies the following conditional formula (40-3), and it is even more preferable that it satisfies the following conditional formula (40-4).
• FIG. 1 is just one example, and various modifications are possible without departing from the spirit of the technology disclosed herein.
• the number of lens groups included in the intermediate group GM, and the number of lenses included in each lens group may be different from those in the example of FIG. 1.
• the intermediate group GM is composed of two lens groups, but in the technology disclosed herein, the intermediate group GM may be configured to be composed of one lens group, three lens groups, four lens groups, or five lens groups.
• the intermediate group GM and the final lens group GE may be configured as described below. When configured as described below, this is advantageous in suppressing aberration fluctuations during magnification change.
• the intermediate group GM may be configured to be composed of, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having negative refractive power, and the final lens group GE may be configured to have positive refractive power.
• the intermediate group GM may be configured to be composed of, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group GE may be configured to have negative refractive power.
• the intermediate group GM may be configured to be composed of, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group GE may be configured to have positive refractive power.
• the intermediate group GM may be configured to have a lens group having positive refractive power, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, in order from the object side to the image side, and the final lens group GE may be configured to have negative refractive power.
• the intermediate group GM may be configured to have a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, in order from the object side to the image side, and the final lens group GE may be configured to have negative refractive power.
• the intermediate group GM may be configured to have a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, in order from the object side to the image side, and the final lens group GE may be configured to have positive refractive power.
• the intermediate group GM is composed of, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group GE may be configured to have negative refractive power.
• the final lens group GE may be configured to move when the magnification is changed. This is advantageous in suppressing aberration fluctuations when the magnification is changed.
• variable magnification optical system disclosed herein may be configured to include multiple lens groups that move along the same movement trajectory when changing magnification from the wide-angle end to the telephoto end.
• the lens groups that move along the same movement trajectory can be driven by a single cam, simplifying the drive mechanism for the lens groups. Note that the above "same movement trajectory when changing magnification from the wide-angle end to the telephoto end" means that the movement trajectory is the same throughout the entire range of magnification from the wide-angle end to the telephoto end.
• variable magnification optical system of the present disclosure may be a zoom lens or a varifocal lens.
• conditional expressions that are preferably satisfied by the variable magnification optical system of the present disclosure are not limited to those written in the form of an expression, but include all conditional expressions obtained by any combination of lower and upper limits from among the conditional expressions that are preferred, more preferred, even more preferred, even more preferred, and even more preferred.
• a first preferred embodiment of the variable magnification optical system of the present disclosure comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an intermediate group GM, and a final lens group GE having refractive power, the intermediate group GM being composed of one or more and five or less lens groups, and during magnification change, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the intermediate group GM changes, and the distance between the intermediate group GM and the final lens group GE changes.
• the intermediate group GM is made up of multiple lens groups, the distance between all of the adjacent lens groups in the intermediate group GM changes during magnification change, an aperture stop St is disposed between the lens surface closest to the image side of the second lens group G2 and the lens surface closest to the object side of the final lens group GE, and the first lens group G1 includes, in order from the most object side to the most image side, a first lens which is a negative lens and a second lens which is a positive lens, and satisfies the above conditional expressions (1), (2), and (3).
• variable magnification optical system of the present disclosure is the first aspect described above, which further satisfies the above conditional expressions (4), (5), (6), and (7).
• variable magnification optical system of the present disclosure will be described with reference to the drawings.
• the reference symbols given to the lenses in the cross-sectional views of each example are used independently for each example to avoid cluttering the explanation and drawings that would otherwise be accompanied by an increase in the number of digits in the reference symbols. Therefore, even if common reference symbols are used in drawings of different examples, this does not necessarily mean that the configuration is the same.
• Example 1 The configuration and movement locus of the variable magnification optical system of Example 1 are shown in Figure 1, and the method of illustration and the configuration are as described above, so some overlapping explanations will be omitted here.
• the variable magnification optical system of Example 1 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the interval between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• variable magnification optical system of Example 1 the basic lens data is shown in Table 1, the specifications and variable surface spacing in Table 2, and the aspheric coefficients in Table 3.
• the table of basic lens data is written as follows.
• the Sn column shows the surface numbers when the surface closest to the object is designated as the first surface and the numbers increase by one toward the image side.
• the R column shows the radius of curvature of each surface.
• the D column shows the surface distance on the optical axis between each surface and its adjacent surface on the image side.
• the Nd column shows the refractive index for the d-line of each component.
• the ⁇ d column shows the Abbe number of each component based on the d-line.
• the ⁇ gF column shows the partial dispersion ratio between the g-line and F-line of each component.
• the ED column shows the effective diameter of each surface.
• Table 1 also shows the aperture stop St, and the surface number and the word (St) are entered in the column for the surface number corresponding to the aperture stop St.
• the value in the bottom row of the surface spacing column in the table is the distance between the surface closest to the image side in the table and the image plane Sim.
• the symbol DD[ ] is used for variable surface spacing, and the surface number on the object side of this distance is entered in [ ] in the surface spacing column.
• Table 2 shows the zoom ratio Zr, focal length f, maximum open F-number FNo., maximum full angle of view 2 ⁇ , and variable surface spacing based on the d-line.
• the zoom ratio is synonymous with the zoom magnification.
• the [°] in the 2 ⁇ column indicates that the unit is degrees.
• the column marked "Wide” shows the values for the wide-angle end state
• the column marked “Middle” shows the values for the intermediate focal length state
• the column marked “Tele” shows the values for the telephoto end state.
• the surface numbers of the aspheric surfaces are marked with *, and the value of the paraxial radius of curvature is written in the column of the radius of curvature of the aspheric surface.
• Table 3 the row Sn shows the surface numbers of the aspheric surfaces, and the rows KA and Am show the numerical values of the aspheric coefficients for each aspheric surface.
• KA and Am are aspheric coefficients in the aspheric formula expressed by the following formula.
• Zd C x h2 / ⁇ 1 + (1 - KA x C2 x h2 ) 1/2 ⁇ + ⁇ Am x hm however,
• Zd Aspheric depth (the length of a perpendicular line drawn from a point on the aspheric surface at height h to a plane perpendicular to the optical axis Z where the apex of the aspheric surface is in contact)
• h Height (distance from optical axis Z to lens surface)
• C reciprocal of paraxial radius of curvature KA
• Am aspheric coefficients, and ⁇ in the aspheric formula represents the summation with respect to m.
• the angle unit is degrees and the length unit is millimeters, but since the optical system can be used with proportional enlargement or reduction, other appropriate units can also be used. Also, in each table below, values are listed rounded to a predetermined number of decimal places.
• Figure 4 shows each aberration diagram of the variable magnification optical system of Example 1 when focused on an object at infinity. From the left, Figure 4 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration.
• the upper row labeled “Wide” shows aberrations at the wide-angle end state
• the middle row labeled “Middle” shows aberrations at the intermediate focal length state
• the lower row labeled “Tele” shows aberrations at the telephoto end state.
• the aberrations at the d-line, C-line, and F-line are shown by solid lines, long dashed lines, and short dashed lines, respectively.
• the aberrations at the d-line in the sagittal direction are shown by solid lines, and the aberrations at the d-line in the tangential direction are shown by short dashed lines.
• the aberrations at the d-line are shown by solid lines.
• the aberrations at the C-line and F-line are shown by long dashed lines and short dashed lines, respectively.
• Example 2 The configuration and movement locus of the variable magnification optical system of Example 2 are shown in FIG. 5.
• the variable magnification optical system of Example 2 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the intervals between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of one lens, L41.
• the fifth lens group G5 consists of one lens, L51.
• variable magnification optical system of Example 2 the basic lens data is shown in Table 4, the specifications and variable surface spacing in Table 5, the aspheric coefficients in Table 6, and the various aberration diagrams in Figure 6.
• Example 3 The configuration and movement locus of the variable magnification optical system of Example 3 are shown in FIG. 7.
• the variable magnification optical system of Example 3 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the intervals between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of one lens, lens L41.
• the fifth lens group G5 consists of one lens, lens L51.
• variable magnification optical system of Example 3 basic lens data is shown in Table 7, specifications and variable surface spacing in Table 8, aspheric coefficients in Table 9, and various aberration diagrams in FIG.
• Example 4 The configuration and movement locus of the variable magnification optical system of Example 4 are shown in FIG. 9.
• the variable magnification optical system of Example 4 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the interval between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of one lens, lens L41.
• the fifth lens group G5 consists of one lens, lens L51.
• variable magnification optical system of Example 4 basic lens data is shown in Table 10, specifications and variable surface spacing in Table 11, aspheric coefficients in Table 12, and various aberration diagrams in FIG.
• Example 5 The configuration and movement locus of the variable magnification optical system of Example 5 are shown in FIG. 11.
• the variable magnification optical system of Example 5 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the interval between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of one lens, lens L41.
• the fifth lens group G5 consists of one lens, lens L51.
• variable magnification optical system of Example 5 basic lens data is shown in Table 13, specifications and variable surface spacing in Table 14, aspheric coefficients in Table 15, and each aberration diagram in FIG.
• Example 6 The configuration and movement locus of the variable magnification optical system of Example 6 are shown in FIG. 13.
• the variable magnification optical system of Example 6 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the intervals between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of one lens, lens L41.
• the fifth lens group G5 consists of one lens, lens L51.
• variable magnification optical system of Example 6 basic lens data is shown in Table 16, specifications and variable surface spacing in Table 17, aspheric coefficients in Table 18, and each aberration diagram in FIG.
• Example 7 The configuration and movement locus of the variable magnification optical system of Example 7 are shown in FIG. 15.
• the variable magnification optical system of Example 7 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the middle group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the interval between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of one lens, lens L41.
• the fifth lens group G5 consists of one lens, lens L51.
• variable magnification optical system of Example 7 basic lens data is shown in Table 19, specifications and variable surface spacing in Table 20, aspheric coefficients in Table 21, and each aberration diagram is shown in FIG.
• Example 8 The configuration and movement locus of the variable magnification optical system of Example 8 are shown in FIG. 17.
• the variable magnification optical system of Example 8 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the interval between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of two lenses, lenses L41 to L42, from the object side to the image side.
• the fifth lens group G5 consists of one lens, lens L51.
• variable magnification optical system of Example 8 the basic lens data is shown in Table 22, the specifications and variable surface spacing in Table 23, the aspheric coefficients in Table 24, and the various aberration diagrams in Figure 18.
• Example 9 The configuration and movement locus of the variable magnification optical system of Example 9 are shown in FIG. 19.
• the variable magnification optical system of Example 9 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3 and the fourth lens group G4.
• the final lens group GE is composed of the fifth lens group G5.
• the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the interval between the adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image surface Sim.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and six lenses, lenses L31 to L36, from the object side to the image side.
• the fourth lens group G4 consists of one lens, lens L41.
• the fifth lens group G5 consists of one lens, lens L51.
• variable magnification optical system of Example 9 the basic lens data is shown in Table 25, the specifications and variable surface spacing in Table 26, the aspheric coefficients in Table 27, and the various aberration diagrams in Figure 20.
• Example 10 The configuration and movement locus of the variable magnification optical system of Example 10 are shown in Figure 21.
• the variable magnification optical system of Example 10 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
• the intermediate group GM is the third lens group G1.
• the fourth lens group G4 and the final lens group GE are made up of the fifth lens group G5.
• the focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and five lenses, lenses L31 to L35, from the object side to the image side.
• the fourth lens group G4 consists of one lens, lens L41.
• the fifth lens group G5 consists of three lenses, lenses L51 to L53, from the object side to the image side.
• variable magnification optical system of Example 10 the basic lens data is shown in Table 28, the specifications and variable surface spacing in Table 29, the aspheric coefficients in Table 30, and the various aberration diagrams in Figure 22.
• Example 11 The configuration and movement locus of the variable magnification optical system of Example 11 are shown in FIG. 23.
• the variable magnification optical system of Example 11 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.
• the final lens group GE is composed of the seventh lens group G7.
• the focusing group is made up of the fifth lens group G5, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and three lenses, L31 to L33, from the object side to the image side.
• the fourth lens group G4 consists of two lenses, L41 to L42, from the object side to the image side.
• the fifth lens group G5 consists of one lens, L51.
• the sixth lens group G6 consists of two lenses, L61 to L62, from the object side to the image side.
• the seventh lens group G7 consists of one lens, L71.
• variable magnification optical system of Example 11 the basic lens data is shown in Table 31, the specifications and variable surface spacing in Table 32, the aspheric coefficients in Table 33, and the various aberration diagrams in Figure 24.
• Example 12 The configuration and movement locus of the variable magnification optical system of Example 12 are shown in FIG. 25.
• the variable magnification optical system of Example 12 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.
• the final lens group GE is composed of the seventh lens group G7.
• all the lens groups move along the optical axis Z while changing the interval between the adjacent lens groups.
• the fourth lens group G4 and the seventh lens group G7 move along the same movement locus.
• the fifth lens group G5 and the sixth lens group G6 move while changing the mutual distance.
• the object-side focusing group is made up of the fifth lens group G5, and the image-side focusing group is made up of the sixth lens group G6.
• the object-side focusing group and the image-side focusing group move toward the object side.
• the first lens group G1 is made up of three lenses, L11 to L13, in order from the object side to the image side.
• the second lens group G2 is made up of four lenses, L21 to L24, in order from the object side to the image side.
• the third lens group G3 is made up of an aperture stop St and two lenses, L31 to L32, in order from the object side to the image side.
• the fourth lens group G4 is made up of two lenses, L41 to L42, in order from the object side to the image side.
• the fifth lens group G5 is made up of two lenses, L51 to L52, in order from the object side to the image side.
• the sixth lens group G6 is made up of one lens, L61.
• the seventh lens group G7 is made up of three lenses, L71 to L73, in order from the object side to the image side.
• variable magnification optical system of Example 12 the basic lens data is shown in Table 34, the specifications and variable surface spacing in Table 35, the aspheric coefficients in Table 36, and the various aberration diagrams in Figure 26.
• Example 13 The configuration and movement locus of the variable magnification optical system of Example 13 are shown in FIG. 27.
• the variable magnification optical system of Example 13 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.
• the final lens group GE is composed of the seventh lens group G7.
• all the lens groups move along the optical axis Z while changing the interval between the adjacent lens groups.
• the fifth lens group G5 and the sixth lens group G6 move while changing the mutual interval.
• the object-side focusing group is made up of the fifth lens group G5
• the image-side focusing group is made up of the sixth lens group G6.
• the first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side.
• the second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, in order from the object side to the image side.
• the fourth lens group G4 consists of two lenses, L41 to L42, in order from the object side to the image side.
• the fifth lens group G5 consists of two lenses, L51 to L52, in order from the object side to the image side.
• the sixth lens group G6 consists of one lens, L61.
• the seventh lens group G7 consists of three lenses, L71 to L73, in order from the object side to the image side.
• variable magnification optical system of Example 13 the basic lens data is shown in Table 37, the specifications and variable surface spacing in Table 38, the aspheric coefficients in Table 39, and each aberration diagram in Figure 28.
• Example 14 The configuration and movement locus of the variable magnification optical system of Example 14 are shown in FIG. 29.
• the variable magnification optical system of Example 14 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.
• the final lens group GE is composed of the seventh lens group G7.
• all the lens groups move along the optical axis Z while changing the interval between the adjacent lens groups.
• the fifth lens group G5 and the sixth lens group G6 move while changing the mutual interval.
• the object-side focusing group is made up of the fifth lens group G5
• the image-side focusing group is made up of the sixth lens group G6.
• the first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side.
• the second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, in order from the object side to the image side.
• the fourth lens group G4 consists of two lenses, L41 to L42, in order from the object side to the image side.
• the fifth lens group G5 consists of two lenses, L51 to L52, in order from the object side to the image side.
• the sixth lens group G6 consists of one lens, L61.
• the seventh lens group G7 consists of three lenses, L71 to L73, in order from the object side to the image side.
• variable magnification optical system of Example 14 the basic lens data is shown in Table 40, the specifications and variable surface spacing in Table 41, the aspheric coefficients in Table 42, and each aberration diagram in Figure 30.
• Example 15 The configuration and movement locus of the variable magnification optical system of Example 15 are shown in FIG. 31.
• the variable magnification optical system of Example 15 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, and the fifth lens group G5.
• the final lens group GE is composed of the sixth lens group G6.
• the focusing group is composed of the fifth lens group G5, and when focusing from an object at infinity to a closest object, the focusing group moves toward the object side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and two lenses, lenses L31 to L32, from the object side to the image side.
• the fourth lens group G4 consists of two lenses, lenses L41 to L42, from the object side to the image side.
• the fifth lens group G5 consists of three lenses, lenses L51 to L53, from the object side to the image side.
• the sixth lens group G6 consists of three lenses, lenses L61 to L63, from the object side to the image side.
• variable magnification optical system of Example 15 the basic lens data is shown in Table 43, the specifications and variable surface spacing in Table 44, the aspheric coefficients in Table 45, and each aberration diagram in Figure 32.
• Example 16 The configuration and movement locus of the variable magnification optical system of Example 16 are shown in FIG. 33.
• the variable magnification optical system of Example 16 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, and the fifth lens group G5.
• the final lens group GE is composed of the sixth lens group G6.
• the focusing group is composed of the fifth lens group G5, and when focusing from an object at infinity to a closest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and two lenses, lenses L31 to L32, from the object side to the image side.
• the fourth lens group G4 consists of four lenses, lenses L41 to L44, from the object side to the image side.
• the fifth lens group G5 consists of three lenses, lenses L51 to L53, from the object side to the image side.
• the sixth lens group G6 consists of one lens, lens L61.
• variable magnification optical system of Example 16 the basic lens data is shown in Table 46, the specifications and variable surface spacing in Table 47, the aspheric coefficients in Table 48, and the various aberration diagrams in Figure 34.
• Example 17 The configuration and movement locus of the variable magnification optical system of Example 17 are shown in Figure 35.
• the variable magnification optical system of Example 17 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.
• the final lens group GE is composed of the seventh lens group G7.
• all the lens groups move along the optical axis Z while changing the interval between the adjacent lens groups.
• the fourth lens group G4 and the sixth lens group G6 move along the same movement locus.
• the focusing group is made up of the fifth lens group G5, and when focusing from an object at infinity to a nearest object, the focusing group moves toward the image side.
• the first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side.
• the second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, in order from the object side to the image side.
• the fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side.
• the fifth lens group G5 consists of three lenses, L51 to L53, in order from the object side to the image side.
• the sixth lens group G6 consists of one lens, L61.
• the seventh lens group G7 consists of one lens, L71.
• variable magnification optical system of Example 17 the basic lens data is shown in Table 49, the specifications and variable surface spacing in Table 50, the aspheric coefficients in Table 51, and each aberration diagram in Figure 36.
• Example 18 The configuration and movement locus of the variable magnification optical system of Example 18 are shown in FIG. 37.
• the variable magnification optical system of Example 18 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.
• the final lens group GE is composed of the seventh lens group G7.
• all the lens groups move along the optical axis Z while changing the interval between the adjacent lens groups.
• the fifth lens group G5 and the sixth lens group G6 move while changing the mutual interval.
• the object-side focusing group is made up of the fifth lens group G5
• the image-side focusing group is made up of the sixth lens group G6.
• the first lens group G1 consists of three lenses, L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and three lenses, L31 to L33, from the object side to the image side.
• the fourth lens group G4 consists of four lenses, L41 to L44, from the object side to the image side.
• the fifth lens group G5 consists of two lenses, L51 to L52, from the object side to the image side.
• the sixth lens group G6 consists of one lens, L61.
• the seventh lens group G7 consists of one lens, L71.
• variable magnification optical system of Example 18 the basic lens data is shown in Table 52, the specifications and variable surface spacing in Table 53, the aspheric coefficients in Table 54, and each aberration diagram in Figure 38.
• Example 19 The configuration and movement locus of the variable magnification optical system of Example 19 are shown in FIG. 39.
• the variable magnification optical system of Example 19 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, and the fifth lens group G5.
• the final lens group GE is composed of the sixth lens group G6.
• all the lens groups move along the optical axis Z while changing the interval between the adjacent lens groups.
• the fourth lens group G4 and the fifth lens group G5 move while changing the mutual interval.
• the object-side focusing group is made up of the fourth lens group G4
• the image-side focusing group is made up of the fifth lens group G5.
• the first lens group G1 consists of three lenses, lenses L11 to L13, from the object side to the image side.
• the second lens group G2 consists of four lenses, lenses L21 to L24, from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and seven lenses, lenses L31 to L37, from the object side to the image side.
• the fourth lens group G4 consists of two lenses, lenses L41 to L42, from the object side to the image side.
• the fifth lens group G5 consists of one lens, lens L51.
• the sixth lens group G6 consists of one lens, lens L61.
• variable magnification optical system of Example 19 the basic lens data is shown in Table 55, the specifications and variable surface spacing in Table 56, the aspheric coefficients in Table 57, and the various aberration diagrams in Figure 40.
• Example 20 The configuration and movement locus of the variable magnification optical system of Example 20 are shown in Figure 41.
• the variable magnification optical system of Example 20 is composed of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, a seventh lens group G7 having positive refractive power, and an eighth lens group G8 having negative refractive power.
• the intermediate group GM is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7.
• the final lens group GE is composed of the eighth lens group G8.
• the first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side.
• the second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side.
• the third lens group G3 consists of an aperture stop St and three lenses, L31 to L33, in order from the object side to the image side.
• the fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side.
• the fifth lens group G5 consists of two lenses, L51 to L52, in order from the object side to the image side.
• the sixth lens group G6 consists of one lens, L61.
• the seventh lens group G7 consists of one lens, L71.
• the eighth lens group G8 consists of one lens, L81.
• variable magnification optical system of Example 20 the basic lens data is shown in Table 58, the specifications and variable surface spacing in Table 59, the aspheric coefficients in Table 60, and the various aberration diagrams in Figure 42.
• Tables 61 to 65 show the corresponding values of conditional expressions (1) to (40) for the variable magnification optical systems of Examples 1 to 20. A "-" is entered in any column that does not have a corresponding lens.
• the corresponding values of the examples shown in Tables 61 to 65 may be used as the upper or lower limits of the conditional expressions to set a preferred range for the conditional expressions.
• variable magnification optical systems of Examples 1 to 20 are constructed to be compact, yet have an F-number of 3.3 or less throughout the entire range of magnification, achieving a small F-number. In particular, some of the examples have an F-number of 3 or less throughout the entire range of magnification. Furthermore, the variable magnification optical systems of Examples 1 to 20 maintain high optical performance with various aberrations well corrected throughout the entire range of magnification.
• Fig. 43 and Fig. 44 show external views of a camera 30 which is an imaging device according to an embodiment of the present disclosure.
• Fig. 43 shows a perspective view of the camera 30 seen from the front side
• Fig. 44 shows a perspective view of the camera 30 seen from the rear side.
• the camera 30 is a so-called mirrorless type digital camera, to which an interchangeable lens 20 can be removably attached.
• the interchangeable lens 20 is configured to include a variable magnification optical system 1 according to an embodiment of the present disclosure housed in a lens barrel.
• Camera 30 has a camera body 31, and a shutter button 32 and a power button 33 are provided on the top surface of camera body 31.
• operation units 34, 35, and a display unit 36 are provided on the back surface of camera body 31.
• Display unit 36 is capable of displaying a captured image and an image within the angle of view before capture.
• a shooting aperture through which light from the subject is incident is provided in the center of the front of the camera body 31, and a mount 37 is provided at a position corresponding to the shooting aperture, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.
• the camera body 31 contains an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, and a recording medium for recording the generated image.
• an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, and a recording medium for recording the generated image.
• CMOS Complementary Metal Oxide Semiconductor
• the technology of the present disclosure has been described above using embodiments and examples, but the technology of the present disclosure is not limited to the above embodiments and examples, and various modifications are possible.
• the radius of curvature, surface spacing, refractive index, Abbe number, aspheric coefficient, etc. of each lens are not limited to the values shown in the above examples, and may take other values.
• the imaging device is not limited to the above example, and can take various forms, such as cameras other than mirrorless type, film cameras, video cameras, and security cameras.
• the optical system comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, an intermediate group, and a final lens group having refractive power, the intermediate group is composed of one or more and five or less lens groups, During magnification change, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the intermediate group changes, and the distance between the intermediate group and the final lens group changes, When the intermediate group is made up of a plurality of lens groups, the intervals between all of the adjacent lens groups in the intermediate group change during magnification.
• an aperture stop is disposed between a lens surface of the second lens group closest to the image side and a lens surface of the final lens group closest to the object side;
• the first lens group includes, in succession from the most object side to the image side, a first lens which is a negative lens and a second lens which is a positive lens;
• the distance on the optical axis from the object side surface of the first lens to the aperture stop when focused on an object at infinity at the wide-angle end is DDL1STw
• TLw is the sum of the distance on the optical axis from the object side surface of the first lens to the lens surface of the final lens group closest to the image side when focused on an object at infinity at the wide-angle end, and the back focus of the entire system in air equivalent distance;
• the maximum F-number when the lens is focused on an object at infinity at the telephoto end is Fnot.
• the focal length of the entire system when focused on an object at infinity at the telephoto end is ft.
• the focal length of the entire system when focused on an object at infinity at the wide-angle end is fw.
• the back focus of the entire system at the wide-angle end in terms of air is Bfw, If the maximum half angle of view when focused on an object at infinity at the telephoto end is ⁇ t, 0 ⁇ DDL1STw/TLw ⁇ 0.5 (1) 0.5 ⁇ Fnot/(ft/fw) ⁇ 1.3 (2) 0.15 ⁇ Bfw/(ft ⁇ tan ⁇ t) ⁇ 2 (3)
• a variable magnification optical system which satisfies conditional expression (4) expressed by: [Additional Note 3]
• the focal length of the first lens group is f1
• the composite focal length of the optical system from the first lens to the aperture stop in a state in which the focus is on an object at infinity at the wide-angle end is fL1STw, ⁇ 6.6 ⁇ f1/fL1STw ⁇ 1.5 (5) 3.
• variable magnification optical system which satisfies conditional expression (5) represented by: [Additional Note 4]
• the focal length of the first lens group is f1, When the focal length of the first lens is fL1, ⁇ 0.9 ⁇ f1/fL1 ⁇ 0.05 (6)
• the variable magnification optical system according to any one of Supplementary Items 1 to 4, which satisfies conditional expression (7) represented by: fL1STw is a composite focal length of the optical system from the first lens to the aperture stop when the optical system is focused on an object at infinity at the wide-angle end;
• the focal length of the first lens group is f1, When
• variable magnification optical system according to any one of appended items 1 to 8, which satisfies conditional expression (10) represented by: [Additional Item 10] If the focal length of the first lens group is f1, 0.2 ⁇ DDL1STw/f1 ⁇ 0.8 (11) The variable magnification optical system according to any one of appended items 1 to 9, which satisfies conditional expression (11) represented by: [Additional Item 11] If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ⁇ w, 3 ⁇ DDL1STw/ ⁇ (fw ⁇ tan ⁇ w) ⁇ log(ft/fw) ⁇ / ⁇ 9 (12) The variable magnification optical system according to any one of appended items 1 to 10, which satisfies conditional expression (12) represented by: [Additional Item 12] 3 ⁇ TLw/fw ⁇ 8 (13) The variable magnification optical system according to any one of appended items 1
• variable magnification optical system according to any one of appended items 1 to 12, which satisfies conditional expression (14) represented by: [Additional Item 14]
• conditional expression (14) represented by: [Additional Item 14]
• variable magnification optical system according to any one of appended items 1 to 13, which satisfies conditional expression (15) represented by: [Additional Item 15] If the focal length of the first lens group is f1, 3 ⁇ f1/fw ⁇ 7 (16) The variable magnification optical system according to any one of appended items 1 to 14, which satisfies conditional expression (16) represented by: [Additional Item 16] The focal length of the first lens group is f1, If the focal length of the second lens group is f2, 3 ⁇ f1/(-f2) ⁇ 9 (17) The variable magnification optical system according to any one of appended items 1 to 15, which satisfies conditional expression (17) represented by: [Additional Item 17] If the focal length of the first lens group is f1, 2 ⁇ f1/(ft/Fnot) ⁇ 7 (18) The variable magnification optical system according to any one of appended items 1 to 16, which satisfies conditional expression (18)
• a variable magnification optical system according to any one of claims 1 to 17, which satisfies conditional expression (19) represented by: [Additional Item 19]
• the distance on the optical axis from the object side surface of the first lens to the paraxial entrance pupil position when focused on an object at infinity at the wide-angle end is Denw, If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ⁇ w, 2 ⁇ Den/ ⁇ (f ⁇ tan ⁇ ) ⁇ log(ft/f) ⁇ 4.5 (20) 19.
• a variable magnification optical system according to any one of claims 1 to 18, which satisfies conditional expression (20) represented by: [Additional Item 20]
• conditional expression (20) represented by: [Additional Item 20]
• the distance on the optical axis from the object side surface of the first lens to the paraxial entrance pupil position in a state in which the object is focused on an object at infinity at the wide-angle end is Denw, 0.5 ⁇ Denw/(fw ⁇ ft) 1/2 ⁇ 1 (21) 20.
• a variable magnification optical system according to any one of claims 1 to 19, which satisfies conditional expression (21) represented by: [Additional Item 21]
• the center thickness of the first lens is d1.
• the distance on the optical axis from the object side surface of the first lens to the paraxial entrance pupil position when focused on an object at infinity at the wide-angle end is Denw, If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ⁇ w, 0.04 ⁇ d1/(Den ⁇ tan ⁇ ) ⁇ 0.09 (22)
• the distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity at the wide-angle end is Dexw.
• the sign of Dexw is positive for the distance on the image side and negative for the distance on the object side with respect to the image surface.
• an optical element having no refractive power is disposed between the image surface and the paraxial exit pupil position
• Dexw for the optical element using an air-equivalent distance ⁇ 0.65 ⁇ fw/Dexw ⁇ 0.2 (23) 22.
• the effective diameter of the object side surface of the first lens is EDf.
• variable magnification optical system according to any one of appended items 1 to 22, which satisfies conditional expression (24) represented by: [Additional Item 24]
• conditional expression (24) represented by: [Additional Item 24]
• the refractive index of the first lens with respect to the d-line is NdL1, When the Abbe number of the first lens based on the d-line is ⁇ dL1, 1.8 ⁇ NdL1 ⁇ 2.01 (27) 15 ⁇ dL
• variable magnification optical system according to any one of appended items 1 to 28, which satisfies conditional expression (34) represented by: [Additional Item 30] 30.
• variable magnification optical system wherein the focusing group is made up of one positive lens and two negative lenses.
• the negative lens closest to the image side of the focusing group is an aspheric lens;
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcnf
• the paraxial radius of curvature of the image-side surface of the aspheric lens is Rcnr
• Rynf is the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rynr, 0.1 ⁇ (1/Rcnf-1/Rcnr)/(1/Rynf-1/Rynr) ⁇ 3 (35)
• variable magnification optical system wherein the focusing group is made up of one negative lens and two positive lenses.
• the positive lens closest to the image side of the focusing group is an aspheric lens;
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcpf
• the paraxial radius of curvature of the image-side surface of the aspheric lens is Rcpr
• Rypf is the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rypr, ⁇ 120 ⁇ (1/Rcpf ⁇ 1/Rcpr)/(1/Rypf ⁇ 1/Rypr) ⁇ 3 (36)
• the variable magnification optical system according to claim 33 which satisfies conditional expression (36) represented by: [Additional Item 35] 31.
• variable magnification optical system wherein the focusing group is made up of one positive lens and one negative lens.
• the focusing group is composed of one negative lens.
• the negative lens in the focusing group is an aspheric lens;
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcsnf
• the paraxial radius of curvature of the image-side surface of the aspheric lens is Rcsnr
• Rysnf is the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens,
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rysnr, 0.1 ⁇ (1/Rcsnf-1/Rcsnr)/(1/Rysnf-1/Rysnr) ⁇ 3.5
• variable magnification optical system any one of appended items 1 to 29, wherein two of the lens groups included in the intermediate group are focusing groups that move while changing the distance between them during magnification and focusing.
• the object-side focusing group is composed of one negative lens and one positive lens, 39.
• the positive lens of the image-side focusing group is an aspheric lens
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rcipf
• the paraxial radius of curvature of the image-side surface of the aspheric lens is Rcipr
• Rypf is the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rypr, 1 ⁇ (1/Rcipf-1/Rcipr)/(1/Ryipf-1/Ryipr) ⁇ 100 (38) 40.
• variable magnification optical system which satisfies conditional expression (38) represented by: [Additional Item 41]
• conditional expression (38) represented by: [Additional Item 41]
• the object-side focusing group is composed of one positive lens and one negative lens, 39.
• the variable magnification optical system according to claim 38 wherein the image-side focusing group is composed of one negative lens.
• the negative lens of the image-side focusing group is an aspheric lens;
• the paraxial radius of curvature of the object side surface of the aspheric lens is Rc inf
• the paraxial radius of curvature of the image-side surface of the aspheric lens is Rcinr
• the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is Ryinf
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Ryinr, 0.1 ⁇ (1/Rcinf-1/Rcinr)/(1/Ryinf-1/Ryinr) ⁇ 3.5 (39) 42.
• variable magnification optical system which satisfies conditional expression (39) represented by: [Additional Item 43] 43.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power and a lens group having negative refractive power, 45.
• variable magnification optical system according to any one of claims 1 to 44, wherein the final lens group has a positive refractive power.
• Additional Item 46 46.
• the final lens group is composed of one positive aspheric lens,
• the paraxial radius of curvature of the object side surface of the aspheric lens is RcEpf
• the paraxial radius of curvature of the image-side surface of the aspheric lens is RcEpr
• the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is RyEpf
• the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is RyEpr, 0.1 ⁇
• variable magnification optical system which satisfies conditional expression (40) represented by: [Additional Item 48] 46.
• the variable magnification optical system according to claim 45 wherein the final lens group moves during magnification variation.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having negative refractive power; 45.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power; 45.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power; 45.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, 45.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power; 45.
• variable magnification optical system according to any one of claims 1 to 44, wherein the final lens group has negative refractive power.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power; 45.
• the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having negative refractive power, and a lens group having positive refractive power; 45.
• 56. The variable magnification optical system according to any one of Addendums 49 to 55, wherein the final lens group moves during magnification variation.
• An imaging apparatus comprising the variable magnification optical system according to any one of claims 1 to 56.

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• 2023
  • 2023-09-12 CN CN202380068704.XA patent/CN119948380A/zh active Pending
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  • 2023-09-12 WO PCT/JP2023/033225 patent/WO2024070667A1/ja not_active Ceased
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  • 2025-03-25 US US19/090,299 patent/US20250224599A1/en active Pending

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