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US-20260126632-A1 - ZOOM LENS AND IMAGING APPARATUS

US20260126632A1US 20260126632 A1US20260126632 A1US 20260126632A1US-20260126632-A1

Abstract

The zoom lens consists of, in order from an object side, a first lens group that has a positive refractive power, a second lens group that has a negative refractive power, a middle group that includes one or more lens groups, and a final lens group. The middle group has a positive refractive power as a whole throughout an entire zoom range. During zooming, a spacing between the first lens group and the second lens group changes, a spacing between the second lens group and the middle group changes, and a spacing between the middle group and the final lens group changes. The zoom lens satisfies predetermined conditional expressions.

Inventors

  • TAIGA NODA

Assignees

  • FUJIFILM CORPORATION

Dates

Publication Date
20260507
Application Date
20260102
Priority Date
20220328

Claims (20)

  1. 1 . A zoom lens comprising, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; a middle group that consists of two or three lens groups; and a final lens group that has a negative refractive power, wherein the middle group has a positive refractive power as a whole throughout an entire zoom range, during zooming, a spacing between the first lens group and the second lens group changes, a spacing between the second lens group and the middle group changes, and a spacing between the middle group and the final lens group changes, and all spacings of adjacent lens groups in the middle group change during zooming, the zoom lens includes a focus group that moves along an optical axis during focusing, the focus group has a negative refractive power, and a focal length of the zoom lens in a state where an infinite distance object is in focus at a wide angle end is fw, a focal length of the zoom lens in a state where the infinite distance object is in focus at a telephoto end is ft, a central thickness of a lens closest to the object side in the first lens group is d1, a distance on an optical axis from a lens surface closest to the object side in the first lens group to a lens surface closest to the image side in the first lens group is DG1, an Abbe number of a lens which is third from the object side in the first lens group based on a d line is νd3, and Conditional Expressions (1), (24) and (26) are satisfied, which are represented by 6 < ft / fw < 30 ( 1 ) 0.06 < d ⁢ 1 / DG ⁢ 1 < 0 . 1 ⁢ 25 ( 24 ) 70 < v ⁢ d ⁢ 3 < 110. ( 26 )
  2. 2 . The zoom lens according to claim 1 , wherein an Abbe number of the lens closest to the object side in the first lens group based on a d line is νd1, and Conditional Expression (2) is satisfied, which is represented by 29.6 < vd ⁢ 1 < 50. ( 2 )
  3. 3 . The zoom lens according to claim 1 , wherein an Abbe number of a lens which is second from the object side in the first lens group based on a d line is νd2, and Conditional Expression (3) is satisfied, which is represented by 6 ⁢ 8 < ( v ⁢ d ⁢ 2 + vd ⁢ 3 ) / 2 < 98. ( 3 )
  4. 4 . The zoom lens according to claim 1 , wherein the first lens group consists of, in order from the object side to the image side, a negative lens, a positive lens, and a positive lens.
  5. 5 . The zoom lens according to claim 1 , wherein the middle group includes a lens group that has a positive refractive power at a position closest to the object side.
  6. 6 . The zoom lens according to claim 1 , wherein a lens group closest to the object side in the middle group includes, successively in order from the object side to the image side, a positive lens, a positive lens, and a negative lens.
  7. 7 . The zoom lens according to claim 1 , wherein a back focal length of the zoom lens at an air-equivalent distance in a state where the infinite distance object is in focus at the wide angle end is βfw, a focal length of the zoom lens in a state where an infinite distance object is in focus at a wide angle end is fw, a maximum half angle of view in a state where the infinite distance object is in focus at the wide angle end is ωw, and Conditional Expression (8) is satisfied, which is represented by 0.5 < Bfw / ( fw × tan ⁢ ω ⁢ w ) < 1.1 . ( 8 )
  8. 8 . The zoom lens according to claim 1 , wherein an average value of specific gravities of all lenses in the focus group is Gfave, and Conditional Expression (11) is satisfied, which is represented by 2.3 < Gfave < 5.15 . ( 11 )
  9. 9 . The zoom lens according to claim 1 , wherein the focus group includes at least one negative lens, a specific gravity of the at least one negative lens in the focus group is Gfn, and Conditional Expression (12) is satisfied, which is represented by 2.4 < Gfn < 5.6 . ( 12 )
  10. 10 . The zoom lens according to claim 1 , wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction, an average value of specific gravities of all lenses in the vibration-proof group is GISave, and Conditional Expression (13) is satisfied, which is represented by 2.5 < GISave < 5.2 . ( 13 )
  11. 11 . The zoom lens according to claim 1 , wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction, the vibration-proof group includes at least one positive lens, a specific gravity of the at least one positive lens in the vibration-proof group is GISp, and Conditional Expression (14) is satisfied, which is represented by 2.6 < GISp < 5. ( 14 )
  12. 12 . The zoom lens according to claim 1 , wherein a central thickness of a lens which is second from the object side in the first lens group is d2, a paraxial curvature radius of an object side surface of the lens which is second from the object side in the first lens group is R2f, a paraxial curvature radius of an image side surface of the lens which is second from the object side in the first lens group is R2r, and Conditional Expression (22) is satisfied, which is represented by 0.06 < d ⁢ 2 × ( 1 / R ⁢ 2 ⁢ f - 1 / R ⁢ 2 ⁢ r ) < 0.19 . ( 22 )
  13. 13 . The zoom lens according to claim 1 , wherein a focal length of the first lens group is f1, and Conditional Expression (23) is satisfied, which is represented by 0.01 < d ⁢ 1 / f ⁢ 1 < 0.021 . ( 23 )
  14. 14 . The zoom lens according to claim 1 , wherein a focal length of the focus group is ffoc, a focal length of the zoom lens in a state where the infinite distance object is in focus at a telephoto end is ft, and Conditional Expression (31) is satisfied, which is represented by - 0.35 < ffoc / ft < - 0.02 . ( 31 )
  15. 15 . The zoom lens according to claim 1 , wherein the zoom lens includes a vibration-proof group that moves in a direction intersecting with an optical axis during image shake correction, a focal length of the vibration-proof group is fIS, a focal length of the zoom lens in a state where the infinite distance object is in focus at a telephoto end is ft, and Conditional Expression (32) is satisfied, which is represented by 0.01 < ❘ fIS / ft ❘ < 0.35 . ( 32 )
  16. 16 . The zoom lens according to claim 1 , wherein a focal length of the first lens group is f1, a focal length of the second lens group is f2, and Conditional Expression (40) is satisfied, which is represented by - 10 < f ⁢ 1 / f ⁢ 2 < - 5.6 . ( 40 )
  17. 17 . The zoom lens according to claim 1 , wherein the number of lenses included in the focus group is two or less.
  18. 18 . The zoom lens according to claim 1 , wherein the zoom lens includes a plurality of lens groups that move on the same movement locus during zooming from the wide angle end to the telephoto end.
  19. 19 . The zoom lens according to claim 18 , wherein the focus group is located between the plurality of lens groups that move on the same movement locus.
  20. 20 . The zoom lens according to claim 1 , wherein a lens group which is fourth from the object side in the zoom lens and the final lens group move on the same movement locus during zooming from the wide angle end to the telephoto end.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/182,104, filed on Mar. 10, 2023, which claims priority from Japanese Patent Application No. 2022-052532, filed on Mar. 28, 2022, the entire disclosure of which is incorporated herein by reference. BACKGROUND Technical Field The technique of the present disclosure relates to a zoom lens and an imaging apparatus. Related Art In the related art, as a zoom lens that can be used in an imaging apparatus such as a digital camera, a zoom lens described in JP2020-086305A below is known. There is a demand for a zoom lens which has a high zoom ratio and maintains favorable optical performance while being configured to have a small size. The demand level is increasing year by year. SUMMARY An object of the present disclosure is to provide a zoom lens, which has a high zoom ratio and maintains favorable optical performance while being configured to have a small size, and an imaging apparatus comprising the zoom lens. According to one aspect of the present disclosure, there is provided a zoom lens consisting of, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; a middle group that includes one or more lens groups; and a final lens group. The middle group has a positive refractive power as a whole throughout an entire zoom range. During zooming, a spacing between the first lens group and the second lens group changes, a spacing between the second lens group and the middle group changes, and a spacing between the middle group and the final lens group changes. In a case where the middle group includes a plurality of lens groups, all spacings of adjacent lens groups in the middle group change during zooming. Assuming that a focal length of a whole system in a state where an infinite distance object is in focus at a wide angle end is fw, and a focal length of the whole system in a state where the infinite distance object is in focus at a telephoto end is ft, Conditional Expression (1) is satisfied, which is represented by 6<ft/fw<30.(1) It is preferable that the zoom lens of the above-mentioned aspect satisfies Conditional Expression (1-1). 7.5<ft/fw<20(1-1) Assuming that an Abbe number of a lens closest to the object side in the first lens group based on a d line is νd1, it is preferable that the zoom lens according to the above-mentioned aspect satisfies Conditional Expression (2), which is represented by 29.6<ν⁢d⁢1<50.(2) Assuming that an Abbe number of a lens which is second from the object side in the first lens group based on a d line is νd2, and an Abbe number of a lens which is third from the object side in the first lens group based on the d line is νd3, it is preferable that the zoom lens according to the above-mentioned aspect satisfies Conditional Expression (3), which is represented by 68<(ν⁢d⁢2+ν⁢d⁢3)/2<98.(3) The final lens group may be configured to have a negative refractive power. The first lens group may be configured to consist of a negative lens, a positive lens, and a positive lens, in order from the object side to the image side. It is preferable that the zoom lens according to the above-mentioned aspect includes a focus group that moves along an optical axis during focusing. It is preferable that the focus group has a negative refractive power. It is preferable that the focus group includes a positive lens and a negative lens. The focus group may be configured to consist of a cemented lens in which a positive lens and a negative lens are cemented to each other. A lens group which is fourth from the object side in the zoom lens may be configured to be a focus group that moves along an optical axis during focusing. It is preferable that the middle group includes at least one lens group that has a positive refractive power. The middle group may be configured to include a lens group that has a positive refractive power at a position closest to the object side. The middle group may be configured to include, successively in order from a position closest to the object side to the image side, a lens group that has a positive refractive power and a lens group that has a negative refractive power. A configuration may be made such that all the lens groups move during zooming. The zoom lens according to the above-mentioned aspect may be configured to consist of five lens groups as a whole. Alternatively, the zoom lens according to the above-mentioned aspect may be configured to consist of six lens groups as a whole. A lens group closest to the object side in the middle group may be configured to include, successively in order from the object side to the image side, a positive lens, a positive lens, and a negative lens. The lens group closest to the object side in the middle group may be configured to include, successively in order from the image side to the object side, a positive lens, a pos