# US 9,753,250 B2 · Wide angle lens and image pickup apparatus using the same

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- Number: US 9,753,250 B2
- Document ID: US9753250B2
- Status: Granted
- Kind: B2
- Application number: 14/716,523
- Filed: 2015-05-19
- Published: 2015-11-26
- Granted: 2017-09-05
- Earliest claimed: 2014-05-26
- Assignees: Olympus Corporation
- Applicants: Olympus Corporation
- Inventors: Akinori Nishio; Masahiro Imamura; Tomoyuki Satori; Koji Nakagawa
- Web page: https://patentgrep.com/patent/US9753250B2

## CPC

- G02B 9/64: having more than six components
- G02B 13/04: Reversed telephoto objectives
- G02B 13/18: with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)}
- G02B 27/0025: {for optical correction, e.g. distorsion, aberration}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A wide angle lens includes in order from an object side, a front lens unit having a positive refractive power, one focusing lens having a negative refractive power, and a rear lens unit having a positive refractive power, and at the time of focusing, the focusing lens moves on an optical axis, and the following conditional expressions (1) and (2) are satisfied. 0.1<f1/SSD<0.5 (1) 3.0≦f23/f (2)

## Claims

### Claim 1

A wide angle lens comprising in order from an object side:
a front lens unit having a positive refractive power;
one focusing lens having a negative refractive power; and
a rear lens unit having a positive refractive power, wherein
at the time of focusing, the focusing lens moves on an optical axis, and
the following conditional expressions (1) and (2) are satisfied:
0.1<f1/SSD<0.5 (1)
3.0≦f23/f (2)
where,
f1 denotes a focal length of the front lens unit;
SSD denotes a distance from a lens surface nearest to an object of the wide angle lens up to an imaging surface, at the time of infinite object point focusing;
f23 denotes a focal length of a lens system in which, the focusing lens and the rear lens unit are combined, at the time of infinite object point focusing; and
f denotes a focal length of an overall wide angle lens system.

### Claim 2 (depends on 1)

The wide angle lens according to claim 1, wherein
a first lens is positioned nearest to an object in the front lens unit, and
the first lens satisfies the following conditional expression (6):
0.5<(rL1f+rL1r)/(rL1f−rL1r)<3 (6)
where,
rL1f denotes a paraxial radius of curvature of an object-side surface of the first lens, and
rL1r denotes a paraxial radius of curvature of an image-side surface of the first lens.

### Claim 3 (depends on 1)

The wide angle lens according to claim 1, wherein the following conditional expression (7) is satisfied:
0.4<(rFof+rFor)/(rFof−rFor)<4 (7)
where,
rFof denotes a paraxial radius of curvature of an object-side surface of the focusing lens, and
rFor denotes a paraxial radius of curvature of an image-side surface of the focusing lens.

### Claim 4 (depends on 1)

The wide angle lens according to claim 1, wherein the following conditional expression (8) is satisfied:
(1−mgFo2)×mgR2<−0.4 (8)
where,
mgFo denotes a lateral magnification of the focusing lens, and
mgR denotes a lateral magnification of the rear lens unit.

### Claim 5 (depends on 1)

The wide angle lens according to claim 1, wherein the following conditional expression (9) is satisfied:
ndFo≦1.6 (9)
where,
ndFo denotes a refractive index for a d-line of the focusing lens.

### Claim 6 (depends on 1)

The wide angle lens according to claim 1, wherein the following conditional expression (10) is satisfied:
νdFo≧55.0 (10)
where,
νdFo denotes Abbe's number for the focusing lens.

### Claim 7 (depends on 1)

An image pickup apparatus comprising:
a wide angle lens according to claim 1; and
an image pickup element which has an image pickup surface, and which converts an image formed by the wide angle lens on the image pickup surface, to an electric signal.

### Claim 8

A wide angle lens comprising in order from an object side:
a front lens unit having a positive refractive power;
one focusing lens having a negative refractive power; and
a rear lens unit having a positive refractive power, wherein
at the time of focusing, the focusing lens moves on an optical axis, and
the following conditional expressions (3), (4), and (5) are satisfied:
0.8<f1/f<1.2 (3)
|f1/f23|<0.5 (4)
0.03<Fno/(f×21.633/Y)<0.08 (5)
where,
f1 denotes a focal length of the front lens unit,
f23 denotes a focal length of a lens system in which, the focusing lens and the rear lens unit are combined, at the time of infinite object point focusing,
f denotes a focal length of an overall wide angle lens system,
Fno denotes an F-number of the overall wide angle lens system, and
Y denotes a maximum image height at an imaging surface of the wide angle lens.

### Claim 9 (depends on 8)

The wide angle lens according to claim 8, wherein
a first lens is positioned nearest to an object in the front lens unit, and
the first lens satisfies the following conditional expression (6A):
0.4<(rL1f+rL1r)/(rL1f−rL1r)<6 (6A)
where,
rL1f denotes a paraxial radius of curvature of an object-side surface of the first lens, and
rL1r denotes a paraxial radius of curvature of an image-side surface of the first lens.

### Claim 10 (depends on 8)

The wide angle lens according to claim 8, wherein the following conditional expression (7A) is satisfied:
0.4<(rFof+rFor)/(rFof−rFor)<3 (7A)
where,
rFof denotes a paraxial radius of curvature of an object-side surface of the focusing lens, and
rFor denotes a paraxial radius of curvature of an image-side surface of the focusing lens.

### Claim 11 (depends on 8)

The wide angle lens according to claim 8, wherein the following conditional expression (8) is satisfied:
(1−mgFo2)×mgR2<−0.4 (8)
where,
mgFo denotes a lateral magnification of the focusing lens, and
mgR denotes a lateral magnification of the rear lens unit.

### Claim 12 (depends on 8)

The wide angle lens according to claim 8, wherein the following conditional expression (9A) is satisfied:
ndFo≦1.75 (9A)
where,
ndFo denotes a refractive index for a d-line of the focusing lens.

### Claim 13 (depends on 8)

The wide angle lens according to claim 8, wherein the following conditional expression (10) is satisfied:
νdFo≧55.0 (10)
where,
νdFo denotes Abbe's number for the focusing lens.

### Claim 14 (depends on 8)

An image pickup apparatus comprising:
a wide angle lens according to claim 8; and
an image pickup element which has an image pickup surface, and which converts an image formed by the wide angle lens on the image pickup surface, to an electric signal.