# US 12,601,898 B2 · Imaging lens and imaging apparatus

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- Number: US 12,601,898 B2
- Document ID: US12601898B2
- Status: Granted
- Kind: B2
- Application number: 18/470,035
- Filed: 2023-09-19
- Published: 2024-01-04
- Granted: 2026-04-14
- Earliest claimed: 2021-03-29
- Assignees: FUJIFILM Corporation
- Applicants: FUJIFILM Corporation
- Inventors: Shunsuke Miyagishima; Hiroki Saito; Kosuke Takahashi; Tomoki Otsuki
- Web page: https://patentgrep.com/patent/US12601898B2

## CPC

- G02B 13/0045: {having five or more lenses}
- G02B 9/64: having more than six components
- G02B 13/00: Optical objectives specially designed for the purposes specified below (with variable magnification {in general} G02B15/00)
- G02B 13/18: with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)}
- H04N 23/951: by using two or more images to influence resolution, frame rate or aspect ratio
- G02B 27/646: {compensating for small deviations, e.g. due to vibration or shake (movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68)}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

The imaging lens includes, successively in order from a position closest to an object side: a first lens group that remains stationary with respect to an image plane during focusing; and a focus lens group that moves along an optical axis during focusing. Assuming that a maximum image height is Ymax, and a focal length of the imaging lens is f, and a sum of a back focal length in terms of an air-equivalent distance and a distance on the optical axis from a lens surface closest to the object side to a lens surface closest to the image side is TL, the imaging lens satisfies Conditional Expressions (1) and (2). 0.1<Ymax/f<0.26 (1): 0.4<TL/f<1.1 (2):

## Claims

### Claim 1

An imaging lens comprising, successively in order from a position closest to an object side to an image side:
a first lens group that remains stationary with respect to an image plane during focusing; and
a focus lens group that moves along an optical axis during focusing,
wherein assuming that
a maximum image height is Ymax,
a focal length of the imaging lens in a state where an infinite distance object is in focus is f, and
a sum of a back focal length in terms of an air-equivalent distance and 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 imaging lens in a state where the infinite distance object is in focus is TL,
Conditional Expressions (1) and (2) are satisfied, which are represented by
0.1<Ymax/f<0.26 (1), and
0.4<TL/f<1.1 (2), and
wherein the imaging lens consists of, in order from the object side to the image side, the first lens group, the focus lens group that has a negative refractive power as a whole, and a rear lens group that remains stationary with respect to the image plane during focusing, and
assuming that a focal length of the rear lens group is fR, Conditional Expression (13) is satisfied, which is represented by
−0.9<fR/f<−0.1 (13).

### Claim 2 (depends on 1)

The imaging lens according to claim 1, wherein assuming that
an amount of distortion at an image height, which is 50% of the maximum image height in a state where the infinite distance object is in focus, is Dst5, and
an amount of distortion at the maximum image height in a state where the infinite distance object is in focus is Dst10,
Conditional Expression (3) is satisfied, which is represented by
0.2<|Dst5/Dst10|<0.6 (3).

### Claim 3 (depends on 1)

The imaging lens according to claim 1, wherein assuming that
a distance on the optical axis from the image plane to an exit pupil position in a state where the infinite distance object is in focus is Pe,
where a sign of Pe is positive in a case where the exit pupil position is closer to the object side than the image plane, and is negative in a case where the exit pupil position is closer to the image side than the image plane,
Conditional Expression (4) is satisfied, which is represented by
1.5<Pe/Ymax<3 (4).

### Claim 4 (depends on 1)

The imaging lens according to claim 1, further comprising a negative lens at a position closest to the image side,
wherein assuming that
a curvature radius of an object side surface of the negative lens is Rf, and
a curvature radius of an image side surface of the negative lens is Rr,
Conditional Expression (5) is satisfied, which is represented by
−0.6<(Rf−Rr)/(Rf+Rr)<−0.1 (5).

### Claim 5 (depends on 4)

The imaging lens according to claim 4, further comprising a positive lens adjacent to the negative lens on the object side of the negative lens,
wherein assuming that a curvature radius of an image side surface of the positive lens is Rpr, Conditional Expression (6) is satisfied, which is represented by
0.03<(Rpr−Rf)/(Rpr+Rf)<0.4 (6).

### Claim 6 (depends on 4)

The imaging lens according to claim 4, wherein assuming that an Abbe number of the negative lens based on a d line is vn, Conditional Expression (7) is satisfied, which is represented by
12<vn<30 (7).

### Claim 7 (depends on 1)

The imaging lens according to claim 1, wherein assuming that a distance on the optical axis from the 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, Conditional Expression (8) is satisfied, which is represented by
0.02<DG1/f<0.2 (8).

### Claim 8 (depends on 1)

The imaging lens according to claim 1, wherein assuming that
a maximum half angle of view in a state where the infinite distance object is in focus is ω, and
an angle between an axis parallel to the optical axis and a principal ray with the maximum image height toward the image plane from a lens closest to the image side in a state where the infinite distance object is in focus is ωi,
Conditional Expression (9) is satisfied, which is represented by
1.4<tan ωi/tan ω<3.6 (9).

### Claim 9 (depends on 1)

The imaging lens according to claim 1, wherein assuming that
a maximum effective diameter of the lens surface closest to the object side in the first lens group is φf, and
a maximum effective diameter of the lens surface closest to the image side in the imaging lens is φr,
Conditional Expression (10) is satisfied, which is represented by
0.2<φf/φr<1.5 (10).

### Claim 10 (depends on 1)

The imaging lens according to claim 1, wherein assuming that a back focal length in terms of the air-equivalent distance in a state where the infinite distance object is in focus is Bf, Conditional Expression (11) is satisfied, which is represented by
0.4<Bf/Ymax<1.8 (11).

### Claim 11 (depends on 1)

The imaging lens according to claim 1, wherein the focus lens group has a negative refractive power as a whole.

### Claim 12 (depends on 11)

The imaging lens according to claim 11, wherein the number of lenses included in the focus lens group is equal to or less than two.

### Claim 13 (depends on 1)

The imaging lens according to claim 1, wherein assuming that a focal length of the first lens group is f1, Conditional Expression (12) is satisfied, which is represented by
0.25<f1/f<0.5 (12).

### Claim 14 (depends on 1)

The imaging lens according to claim 1,
wherein the imaging lens is provided in an imaging apparatus, and
the imaging apparatus includes an imaging element that captures an optical image formed by the imaging lens, and is capable of outputting an image having an angle of view narrower than a maximum imaging angle of view of the imaging element.

### Claim 15 (depends on 2)

The imaging lens according to claim 2,
wherein the imaging lens is provided in an imaging apparatus, and
the imaging apparatus includes an imaging element that captures an optical image formed by the imaging lens, and is capable of outputting an image having an angle of view narrower than a maximum imaging angle of view of the imaging element.

### Claim 16 (depends on 15)

The imaging lens according to claim 15, wherein the imaging apparatus is capable of outputting the image having the angle of view narrower than the maximum imaging angle of view of the imaging element by using a composite image which is obtained by synthesizing a plurality of images captured by the imaging element.

### Claim 17 (depends on 1)

The imaging lens according to claim 1,
wherein the imaging lens is provided in an imaging apparatus, and
the imaging apparatus includes an imaging element that captures an optical image formed by the imaging lens, and is capable of outputting an image having an angle of view narrower than a maximum imaging angle of view of the imaging element by using a composite image which is obtained by synthesizing a plurality of images captured by the imaging element.

### Claim 18 (depends on 1)

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