Granted Patent B2

US 12,631,853 · App. 18/636,549 · Granted May 19, 2026

Inventor: Kosuke Machida (Tokyo, JP)

Assignee: Nikon Corporation

G02B9/10G02B15/142G02B15/143105G02B15/1451G02B15/145121G02B15/163G02B15/20G02B15/22G02B5/005G02B9/12G02B9/34G02B9/60G02B9/62G02B9/64G02B13/0045G02B13/009G02B13/18G02B15/14G02B15/17

Abstract

Claims (41)

1 . A zoom optical system comprising, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; and a subsequent group including a third lens group, a fourth lens group, and a fifth lens group,

wherein

upon zooming, distances between the first lens group and the second lens group and between the second lens group and the subsequent group change,

the first lens group moves toward the object upon zooming from a wide-angle end state to a telephoto end state,

the fourth lens group is a focusing group for focusing, and

the following conditional expressions are satisfied:

4.30< f 1/(− f 2)<5.00

0.20< f 1/ fR< 0.85

where,

f1 denotes a focal length of the first lens group,

f2 denotes a focal length of the second lens group, and

fR denotes a focal length of a lens component, in the subsequent group, closest to an image surface.

2 . The zoom optical system according to claim 1 , wherein the first lens group has only one cemented lens and one single lens.

3 . The zoom optical system according to claim 1 , wherein the focusing group comprises at least one lens having positive refractive power and at least one lens having negative refractive power.

4 . The zoom optical system according to claim 3 , wherein

the following conditional expression is satisfied:

1.00< nFP/nFN< 1.20

where,

nFP denotes a refractive index of a lens with largest positive refractive power in the focusing group, and

nFN denotes a refractive index of a lens with largest negative refractive power in the focusing group.

5 . The zoom optical system according to claim 3 , wherein

the following conditional expression is satisfied:

0.52<ν FP/νFN< 0.82

where,

νFP denotes an Abbe number of a lens with largest positive refractive power in the focusing group, and

νFN denotes an Abbe number of a lens with largest negative refractive power in the focusing group.

6 . The zoom optical system according to claim 1 , wherein the first lens group includes, in order from the object: the 1-1st lens; a 1-2nd lens having negative refractive power; and a 1-3rd lens having positive refractive power.

7 . The zoom optical system according to claim 1 , wherein the second lens group includes, in order from the object: a 2-1st lens having negative refractive power; a 2-2nd lens having positive refractive power; and a 2-3rd lens having negative refractive power.

8 . An optical apparatus comprising the zoom optical system according to claim 1 .

9 . A method for manufacturing a zoom optical system which comprises, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; and a subsequent group including a third lens group, a fourth lens group, and a fifth lens group,

the method comprising a step of arranging the lens groups in a lens barrel so that:

upon zooming, distances between the first lens group and the second lens group and between the second lens group and the subsequent group change,

the first lens group moves toward the object upon zooming from a wide-angle end state to a telephoto end state,

the fourth lens group is a focusing group for focusing, and

the following conditional expressions are satisfied:

4.30< f 1/(− f 2)<5.00

0.20< f 1/ fR< 0.85

where,

f1 denotes a focal length of the first lens group,

f2 denotes a focal length of the second lens group, and

fR denotes a focal length of a lens component, in the subsequent group, closest to an image surface.

Priority Claims (1)

Continuity (3)

References Cited (25)