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US-12627890-B1 - Zoom lens and imaging apparatus

US12627890B1US 12627890 B1US12627890 B1US 12627890B1US-12627890-B1

Abstract

A zoom lens of the disclosure includes: a first lens group having positive refractive power; a second lens group having negative refractive power; an intermediate lens group including at least one positive lens group and having positive refractive power as a whole; and a rear lens group including at least negative and positive lens groups. When an object distance varies from infinity to a short distance, the negative and positive lens groups in the rear lens group move in an optical axis direction in different trajectories, and the negative lens group in the rear lens group moves to an image plane side. Upon zooming from a wide-angle end to a telephoto end, the first lens group moves to an object side with respect to an image plane, and the first, second, intermediate, and rear lens groups each move to vary an interval between adjacent lens groups on an optical axis.

Inventors

  • Masaki Maruyama

Assignees

  • Sony Group Corporation

Dates

Publication Date
20260512
Application Date
20230206
Priority Date
20220323

Claims (18)

  1. 1 . A zoom lens comprising, in order from a side of an object toward a side of an image plane: a first lens group having positive refractive power; a second lens group having negative refractive power; an intermediate lens group including at least one positive lens group and having positive refractive power as a whole; and a rear lens group including at least a negative lens group and a positive lens group in order from the side of the object, wherein when an object distance varies from infinity to a short distance, focusing is performed by allowing the negative lens group and the positive lens group in the rear lens group to move in an optical axis direction in trajectories different from each other and the negative lens group in the rear lens group to move to the side of the image plane, upon zooming from a wide-angle end to a telephoto end, the first lens group moves to the side of the object with respect to the image plane, and the first lens group, the second lens group, the intermediate lens group, and the rear lens group each move to allow an interval between adjacent lens groups to vary on au optical axis, the intermediate lens group includes at least two negative lenses, and the following conditional expression is satisfied: −0.31≤(1−β rp _ w 2 )/[(1−β rn _ w 2 )*β rp _ w 2 ]≤0 (1) where βrn_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the negative lens group in the rear lens group, and βrp_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the positive lens group in the rear lens group.
  2. 2 . A zoom lens comprising, in order from a side of an object toward a side of an image plane: a first lens group having positive refractive power; a second lens group having negative refractive power; an intermediate lens group including at least one positive lens group and having positive refractive power as a whole; and a rear lens group including at least a negative lens group and a positive lens group in order from the side of the object, wherein when an object distance varies from infinity to a short distance, focusing is performed by allowing the negative lens group and the positive lens group in the rear lens group to move in an optical axis direction in trajectories different from each other and the negative lens group in the rear lens group to move to the side of the image plane, upon zooming from a wide-angle end to a telephoto end, the first lens group moves to the side of the object with respect to the image plane, and the first lens group, the second lens group, the intermediate lens group, and the rear lens group each move to allow an interval between adjacent lens groups to vary on an optical axis, the first lens group includes three lenses, and the following conditional expression is satisfied: −0.31≤(1−β rp _ w 2 )/[(1−β rn _ w 2 )*β rp _ w 2 ]≤0 (1) where βrn_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the negative lens group in the rear lens group, and βrp_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the positive lens group in the rear lens group.
  3. 3 . The zoom lens according to claim 2 , wherein the intermediate lens group includes at least one lens group including the positive lens group, and the at least one lens group in the intermediate lens group moves with respect to the image plane upon zooming.
  4. 4 . The zoom lens according to claim 2 , wherein the intermediate lens group includes two of the positive lens groups.
  5. 5 . The zoom lens according to claim 2 , wherein the intermediate lens group satisfies the following conditional expression: 0.60< fm _ w/fw< 1.60 (2) where fw denotes a focal distance of a total system at the wide-angle end, and fm_w denotes a focal distance of the intermediate lens group at the wide-angle end.
  6. 6 . The zoom lens according to claim 2 , wherein the intermediate lens group satisfies the following conditional expression: 0.25< fm _ t/ft< 0.70 (3) where ft denotes a focal distance of a total system at the telephoto end, and fm_t denotes a focal distance of the intermediate lens group at the telephoto end.
  7. 7 . The zoom lens according to claim 2 , wherein the negative lens group in the rear lens group includes a single lens.
  8. 8 . The zoom lens according to claim 2 , wherein the positive lens group in the rear lens group includes a single lens.
  9. 9 . The zoom lens according to claim 2 , wherein the following conditional expression is further satisfied: 0.2< BF _ w/fw≤ 1.2 (4) where BF_w denotes a back focus, which is a distance to the image plane from a surface of the rear lens group on a side closest to the image plane, upon infinity focusing at the wide-angle end.
  10. 10 . The zoom lens according to claim 2 , wherein the first lens group includes a lens that satisfies the following conditional expression (5): nd _ L 1 i/dL 1 i> 0.50 (5) where nd_L1i denotes a refractive index, with respect to a d-line, of a glass material of the lens that satisfies the conditional expression (5) in the first lens group, and d_L1i denotes a ratio, which is a specific gravity, between a mass of the glass material of the lens at an ordinary temperature, which ranges from 15 degrees Celsius to 25 degrees Celsius, and a mass of pure water of a same volume at four degrees Celsius under a pressure of 101.325 kPa, which is a standard atmospheric pressure, the lens satisfying the conditional expression (5) and being in the first lens group.
  11. 11 . The zoom lens according to claim 2 , wherein the second lens group includes a positive lens that satisfies the following conditional expression (6): 1.955< nd _ L 2 p (6) where nd_L2p denotes a refractive index, with respect to a d-line, of the positive lens that satisfies the conditional expression (6) in the second lens group.
  12. 12 . The zoom lens according to claim 2 , wherein the intermediate lens group includes a positive lens on which an aspherical surface is formed, the aspherical surface partially having a negative refractive action.
  13. 13 . The zoom lens according to claim 2 , wherein the first lens group includes a positive lens that satisfies the following conditional expression (7): θ gF _ L 1 p −(−0.001801*ν d _ L 1 p+ 0.648262)>0.005 (7) where θgF_L1p denotes a partial dispersion ratio between a g-line and an F-line of the positive lens that satisfies the conditional expression (7) in the first lens group, and νd_L1p denotes Abbe number, with respect to a d-line, of the positive lens that satisfies the conditional expression (7) in the first lens group.
  14. 14 . The zoom lens according to claim 2 , wherein the first lens group includes a negative lens that satisfies the following conditional expression (8): ν d _ L 1 n< 23.0 (8) where νd_L1n denotes Abbe number, with respect to a d-line, of the negative lens that satisfies the conditional expression (8) in the first lens group.
  15. 15 . The zoom lens according to claim 2 , wherein the intermediate lens group includes a positive lens that satisfies the following conditional expression (9): θ gF _ Lmp −(−0.001801*ν d _ Lmp+ 0.648262)>0.045 (9) where θgF_Lmp denotes a partial dispersion ratio between a g-line and an F-line of the positive lens that satisfies the conditional expression (9) in the intermediate lens group, and νd_Lmp denotes Abbe number, with respect to a d-line, of the positive lens that satisfies the conditional expression (9) in the intermediate lens group.
  16. 16 . The zoom lens according to claim 2 , wherein a lens disposed on a side closest to the image plane in the rear lens group includes a negative lens that satisfies the following conditional expression (10): 0.9<( r 2_ rr+r 1_ rr )/( r 2_ rr−r 1_ rr )<6.9 (10) where r1_rr denotes a curvature radius of a surface, on the side of the object, of the lens disposed on the side closest to the image plane in the rear lens group, and r2_rr denotes a curvature radius of a surface, on the side of the image plane, of the lens disposed on the side closest to the image plane in the rear lens group.
  17. 17 . An imaging apparatus comprising: a zoom lens; and an imaging element that outputs an imaging signal corresponding to an optical image formed by the zoom lens, the zoom lens including, in order from a side of an object toward a side of an image plane a first lens group having positive refractive power, a second lens group having negative refractive power, an intermediate lens group including at least one positive lens group and having positive refractive power as a whole, and a rear lens group including at least a negative lens group and a positive lens group in order from the side of the object, wherein when an object distance varies from infinity to a short distance, focusing is performed by allowing the negative lens group and the positive lens group in the rear lens group to move in an optical axis direction in trajectories different from each other and the negative lens group in the rear lens group to move to the side of the image plane, upon zooming from a wide-angle end to a telephoto end, the first lens group moves to the side of the object with respect to the image plane, and the first lens group, the second lens group, the intermediate lens group, and the rear lens group each move to allow an interval between adjacent lens groups to vary on an optical axis, the intermediate lens group includes at least two negative lenses, and the following conditional expression is satisfied: −0.31≤(1−β rp _ w 2 )/[(1−β rn _ w 2 )*β rp _ w 2 ]≤0 (1) where βrn_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the negative lens group in the rear lens group, and βrp_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the positive lens group in the rear lens group.
  18. 18 . An imaging apparatus comprising: a zoom lens; and an imaging element that outputs an imaging signal corresponding to an optical image formed by the zoom lens, the zoom lens including, in order from a side of an object toward a side of an image plane a first lens group having positive refractive power, a second lens group having negative refractive power, an intermediate lens group including at least one positive lens group and having positive refractive power as a whole, and a rear lens group including at least a negative lens group and a positive lens group in order from the side of the object, wherein when an object distance varies from infinity to a short distance, focusing is performed by allowing the negative lens group and the positive lens group in the rear lens group to move in an optical axis direction in trajectories different from each other and the negative lens group in the rear lens group to move to the side of the image plane, upon zooming from a wide-angle end to a telephoto end, the first lens group moves to the side of the object with respect to the image plane, and the first lens group, the second lens group, the intermediate lens group, and the rear lens group each move to allow an interval between adjacent lens groups to vary on an optical axis, the first lens group includes three lenses, and the following conditional expression is satisfied: −0.31≤(1−β rp _ w 2 )/[(1−β rn _ w 2 )*β rp _ w 2 ]≤0 (1) where βrn_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the negative lens group in the rear lens group, and βrp_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the positive lens group in the rear lens group.

Description

TECHNICAL FIELD The present disclosure relates to a zoom lens and an imaging apparatus. BACKGROUND ART There has been a universal demand for an optical system used in an imaging apparatus: to have a small size and a light weight; to have an F-value that allows for brightness; to have high image quality across the entire focusing region; to have a high maximum photographic magnification; and to balance these elements at a high level. In addition, for example, as a zoom lens including a normal viewing angle range, a positive lead configuration has been proposed, that includes, on a side closest to an object, a lens group of positive refractive power to be extended to an object side in association with a varied magnification, in which focusing from infinity to a short distance is performed by moving a plurality of lens groups separately in order to achieve high image quality across the entire focusing region (see PTLs 1 and 2). CITATION LIST Patent Literature PTL 1: Japanese Unexamined Patent Application Publication No. 2015-102588PTL 2: International Publication No. WO2019/97719 SUMMARY OF THE INVENTION It is difficult for configurations proposed in PTLs 1 and 2 to sufficiently meet demands described above. It is desirable to provide a zoom lens having a large aperture and high optical performance despite a small size and a light weight and balancing a high maximum photographic magnification and suppressed variation in performance caused by a photographic distance, as well as an imaging apparatus including such a zoom lens. A first zoom lens according to an embodiment of the present disclosure includes, in order from a side of an object toward a side of an image plane: a first lens group having positive refractive power; a second lens group having negative refractive power; an intermediate lens group including at least one positive lens group and having positive refractive power as a whole; and a rear lens group including at least a negative lens group and a positive lens group in order from the side of the object. When an object distance varies from infinity to a short distance, focusing is performed by allowing the negative lens group and the positive lens group in the rear lens group to move in an optical axis direction in trajectories different from each other and the negative lens group in the rear lens group to move to the side of the image plane. Upon zooming from a wide-angle end to a telephoto end, the first lens group moves to the side of the object with respect to the image plane, and the first lens group, the second lens group, the intermediate lens group, and the rear lens group each move to allow an interval between adjacent lens groups to vary on an optical axis. The intermediate lens group includes at least two negative lenses. The following conditional expression is satisfied: −0.31≤(1−βrp_w2)/[(1−βrn_w2)*βrp_w2]≤0  (1) where βrn_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the negative lens group in the rear lens group, and βrp_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the positive lens group in the rear lens group. A second zoom lens according to an embodiment of the present disclosure includes, in order from a side of an object toward a side of an image plane: a first lens group having positive refractive power; a second lens group having negative refractive power; an intermediate lens group including at least one positive lens group and having positive refractive power as a whole; and a rear lens group including at least a negative lens group and a positive lens group in order from the side of the object. When an object distance varies from infinity to a short distance, focusing is performed by allowing the negative lens group and the positive lens group in the rear lens group to move in an optical axis direction in trajectories different from each other and the negative lens group in the rear lens group to move to the side of the image plane. Upon zooming from a wide-angle end to a telephoto end, the first lens group moves to the side of the object with respect to the image plane, and the first lens group, the second lens group, the intermediate lens group, and the rear lens group each move to allow an interval between adjacent lens groups to vary on an optical axis. The first lens group includes three lenses. The following conditional expression is satisfied: −0.31≤(1−βrp_w2)/[(1−βrn_w2)*βrp_w2]≤0  (1) where βrn_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the negative lens group in the rear lens group, and βrp_w denotes a lateral magnification upon infinity focusing at the wide-angle end of the positive lens group in the rear lens group. A first imaging apparatus according to an embodiment of the present disclosure includes a zoom lens and an imaging element that outputs an imaging signal corresponding to an optical image formed by the zoom lens, and the zoom lens is co