# US 10,481,371 B2 · Imaging lens and imaging apparatus

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- Number: US 10,481,371 B2
- Document ID: US10481371B2
- Status: Granted
- Kind: B2
- Application number: 15/873,364
- Filed: 2018-01-17
- Published: 2018-07-26
- Granted: 2019-11-19
- Earliest claimed: 2017-01-20
- Assignees: FUJIFILM Corporation
- Applicants: FUJIFILM Corporation
- Inventors: Hiroki Saito; Shunsuke Miyagishima
- Web page: https://patentgrep.com/patent/US10481371B2

## CPC

- G02B 13/06: Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces}
- G02B 3/0037: {characterized by the distribution or form of lenses}
- G02B 3/04: with continuous faces that are rotationally symmetrical but deviate from a true sphere {, e.g. so called "aspheric" lenses}
- G02B 9/64: having more than six components
- G02B 13/0045: {having five or more lenses}
- G02B 15/143: {having three groups only}
- G02B 2207/117: Adjustment of the optical path length
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

The imaging lens consists of a first lens group fixed to an image plane during focusing, an aperture stop, a second lens group having a positive refractive power which moves along an optical axis during focusing, and a third lens group fixed to the image plane during focusing, in order from an object side. The first lens group includes at least two negative lenses among three lenses from a lens closest to the object side to a third lens, a negative lens of the at least two negative lenses closest to the object side being a negative meniscus lens with its convex surface toward the object side, the second lens group includes at least three lenses, and the third lens group includes at least three lenses.

## Claims

### Claim 1

An imaging lens comprising, in order from an object side:
a first lens group fixed to an image plane during focusing;
a stop;
a second lens group having a positive refractive power which moves along an optical axis during focusing; and
a third lens group fixed to the image plane during focusing,
wherein the first lens group includes at least two negative lenses among three lenses from a lens closest to the object side to a third lens, a negative lens of the at least two negative lenses closest to the object side being a negative meniscus lens with its convex surface toward the object side,
the second lens group includes at least three lenses, and
the third lens group includes at least three lenses,
wherein in a case where a focal length of the whole system is set to f, and a focal length of the second lens group is set to f2, the following Conditional Expression (1) is satisfied,
0.1<f/f2<0.6 (1).

### Claim 2 (depends on 1)

The imaging lens according to claim 1,
wherein in a case where a distance on the optical axis from the stop to the image plane is set to BS, a focal length of the whole system is set to f, and a half angle of view of the whole system is set to ω, the following Conditional Expression (2) is satisfied,
2<BS/(f·tan ω)<3 (2).

### Claim 3 (depends on 2)

The imaging lens according to claim 2,
wherein the following Conditional Expression (2-1) is satisfied,
2.2<BS/(f·tan ω)<2.8 (2-1).

### Claim 4 (depends on 1)

The imaging lens according to claim 1,
wherein in a case where a focal length of the second lens group is set to f2, and a focal length of the third lens group is set to f3, the following Conditional Expression (3) is satisfied,
−0.2<f2/f3<0.2 (3).

### Claim 5 (depends on 4)

The imaging lens according to claim 4,
wherein the following Conditional Expression (3-1) is satisfied,
−0.16<f2/f3<0.16 (3-1).

### Claim 6 (depends on 1)

The imaging lens according to claim 1,
wherein in a case where a focal length of the second lens group is set to f2, and a focal length of the first lens group is set to f1, the following Conditional Expression (4) is satisfied,
0<f2/f1<1.5 (4).

### Claim 7 (depends on 6)

The imaging lens according to claim 6,
wherein the following Conditional Expression (4-1) is satisfied,
0.3<f2/f1<0.9 (4-1).

### Claim 8 (depends on 1)

The imaging lens according to claim 1,
wherein in a case where an Abbe number of a positive lens of the second lens group is set to ν2p, the second lens group includes at least one positive lens satisfying the following Conditional Expression (5),
70<ν2p<100 (5).

### Claim 9 (depends on 8)

The imaging lens according to claim 8,
wherein the second lens group includes at least one positive lens satisfying the following Conditional Expression (5-1)
80<ν2p<95 (5-1).

### Claim 10 (depends on 1)

The imaging lens according to claim 1, wherein the third lens group includes a positive lens closest to an image side.

### Claim 11 (depends on 1)

The imaging lens according to claim 1, wherein the first lens group is configured such that two lenses from the lens closest to the object side to a second lens are negative lenses.

### Claim 12 (depends on 1)

The imaging lens according to claim 1, wherein the second lens group consists of three or four lenses.

### Claim 13 (depends on 1)

The imaging lens according to claim 1, wherein the third lens group consists of four or five lenses.

### Claim 14 (depends on 1)

The imaging lens according to claim 1,
wherein the following Conditional Expression (1-1) is satisfied,
0.25<f/f2<0.55 (1-1).

### Claim 15 (depends on 1)

The imaging lens according to claim 1,
wherein the following Conditional Expression (1-2) is satisfied,
0.4<f/f2<0.52 (1-2).

### Claim 16 (depends on 1)

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

### Claim 17

An imaging lens comprising, in order from an object side:
a first lens group fixed to an image plane during focusing;
a stop;
a second lens group having a positive refractive power which moves along an optical axis during focusing; and
a third lens group fixed to the image plane during focusing,
wherein the first lens group includes at least two negative lenses among three lenses from a lens closest to the object side to a third lens, a negative lens of the at least two negative lenses closest to the object side being a negative meniscus lens with its convex surface toward the object side,
the second lens group includes at least three lenses, and
the third lens group includes at least three lenses,
wherein the first lens group includes at least two positive lenses.

### Claim 18 (depends on 17)

An imaging apparatus comprising the imaging lens according to claim 17.

### Claim 19

An imaging lens comprising, in order from an object side:
a first lens group fixed to an image plane during focusing;
a stop;
a second lens group having a positive refractive power which moves along an optical axis during focusing; and
a third lens group fixed to the image plane during focusing,
wherein the first lens group includes at least two negative lenses among three lenses from a lens closest to the object side to a third lens, a negative lens of the at least two negative lenses closest to the object side being a negative meniscus lens with its convex surface toward the object side,
the second lens group includes at least three lenses, and
the third lens group includes at least three lenses,
wherein the first lens group is configured such that three lenses from the lens closest to the object side to the third lens are negative lenses.

### Claim 20 (depends on 19)

An imaging apparatus comprising the imaging lens according to claim 19.