Granted Patent B2

US 12,613,397 · App. 18/304,391 · Granted Apr 28, 2026

Inventors: Yasutaka Shimada (Saitama, JP); Shunsuke Miyagishima (Saitama, JP)

Assignee: FUJIFILM Corporation

G02B13/18G02B9/12G02B15/143503G02B15/22G03B13/34

Abstract

Claims (51)

1 . An imaging lens consisting of, in order from an object side to an image side: a first lens group that has a refractive power; a second lens group that has a positive refractive power; and a third lens group that has a negative refractive power,

wherein during focusing, the first lens group and the third lens group remain stationary with respect to an image plane, and the second lens group moves along an optical axis,

the second lens group includes a stop and at least three negative lenses,

a sum of a distance on the 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 third lens group and a back focal length of the imaging lens in terms of an air-equivalent distance is TTL,

a focal length of the imaging lens in a state in which an infinite distance object is in focus is f,

a maximum half angle of view in a state in which the infinite distance object is in focus is ωm, and

Conditional Expression (1) is satisfied, which is represented by

5 <TTL 2 /( f 2 ×tan ω m )<15  (1),

wherein

a focal length of the first lens group is f1,

a focal length of the third lens group is f3, and

Conditional Expression (6) is satisfied, which is represented by

1.5 <f 3 /f 1<3.5  (6).

2 . The imaging lens according to claim 1 , wherein the back focal length of the imaging lens in terms of the air-equivalent distance is Bf, Conditional Expression (2) is satisfied, which is represented by

0.1 <Bf/f< 0.6  (2).

3 . The imaging lens according to claim 1 , wherein the first lens group is a lens group having a negative refractive power.

4 . The imaging lens according to claim 1 , wherein

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

Conditional Expression (3) is satisfied, which is represented by

−18.5 <f 3 /f 2<−1  (3).

5 . The imaging lens according to claim 1 , wherein

a refractive index of a positive lens closest to the object side among positive lenses in the second lens group at a d line is N2po,

a refractive index of a positive lens closest to the image side among the positive lenses in the second lens group at the d line is N2pi, and

Conditional Expression (4) is satisfied, which is represented by

1.86<( N 2 po+N 2 pi )/2<2.2  (4).

6 . The imaging lens according to claim 1 , wherein

an Abbe number of a positive lens closest to the object side among positive lenses in the second lens group at a d line is ν2po,

an Abbe number of a positive lens closest to the image side among the positive lenses in the second lens group at the d line is ν2pi, and

Conditional Expression (5) is satisfied, which is represented by

15<(ν2 po+ν 2 pi )/2<40  (5).

7 . The imaging lens according to claim 1 , wherein Conditional Expression (7) is satisfied, which is represented by

−0.35< f/f 1<−0.08  (7).

8 . The imaging lens according to claim 1 , wherein a positive lens closest to the image side among positive lenses in the second lens group is cemented to a negative lens.

9 . The imaging lens according to claim 1 , wherein a positive lens closest to the object side among positive lenses in the second lens group is a meniscus lens of which an image side surface is concave.

10 . The imaging lens according to claim 1 , wherein the second lens group includes at least one aspherical lens surface.

11 . The imaging lens according to claim 1 , wherein the third lens group includes at least one aspherical lens surface.

12 . The imaging lens according to claim 1 , wherein the third lens group includes a cemented lens which is formed by cementing a positive lens and a negative lens in order from the object side, and a negative lens which is disposed closest to the image side and of which an object side surface is concave.

13 . The imaging lens according to claim 12 , wherein

an Abbe number of the positive lens of the cemented lens at a d line is ν3p,

an Abbe number of the negative lens of the cemented lens at the d line is ν3n, and

Conditional Expression (8) is satisfied, which is represented by

1<ν3 p −ν3 n< 10  (8).

14 . The imaging lens according to claim 1 , wherein

a distance on the optical axis from a lens surface closest to the object side in the third lens group to the lens surface closest to the image side in the third lens group is DG3, and

the back focal length of the imaging lens in terms of the air-equivalent distance is Bf,

Conditional Expression (9) is satisfied, which is represented by

0.85 <DG 3/ Bf< 2  (9).

15 . The imaging lens according to claim 1 , wherein a lens closest to the object side in the first lens group is a negative lens of which an object side surface is concave.

16 . The imaging lens according to claim 15 , wherein a positive lens is disposed adjacent to the image side of the negative lens closest to the object side in the first lens group.

17 . The imaging lens according to claim 16 , wherein the negative lens closest to the object side in the first lens group is a biconcave lens.

18 . An imaging apparatus comprising the imaging lens according to claim 1 .

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (34)