# US 2014/0153118 A1 · Superwide-angle lens system

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- Number: US 2014/0153118 A1
- Document ID: US20140153118A1
- Status: Published application
- Kind: A1
- Application number: 14/077,758
- Filed: 2013-11-12
- Published: 2014-06-05
- Earliest claimed: 2012-12-03
- Assignees: Ricoh Imaging Company, Ltd.
- Applicants: Ricoh Imaging Company, Ltd.
- Inventors: Tatsuyuki ONOZAKI
- Web page: https://patentgrep.com/patent/US20140153118A1

## CPC

- G02B 13/06: Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces}
- G02B 13/18: with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A superwide-angle lens system includes a positive front lens group and a negative rear lens group, in that order from the object side, wherein the negative rear lens group serves as a focusing lens group that is moved in the optical axis direction when focusing on an object at infinity to an object at a finite distance. The following condition (1) is satisfied: 1.1<mR<2.0 (1), wherein mR designates the lateral magnification of the negative rear lens group when focusing on an object at infinity.

## Claims

### Claim 1

A superwide-angle lens system comprising a positive front lens group and a negative rear lens group, in that order from the object side, wherein said negative rear lens group serves as a focusing lens group that is moved in the optical axis direction when focusing on an object at infinity to an object at a finite distance,
wherein the following condition (1) is satisfied:
1.1<mR<2.0 (1),
wherein
mR designates the lateral magnification of said negative rear lens group when focusing on an object at infinity.

### Claim 2 (depends on 1)

The superwide-angle lens system according to claim 1, wherein the following condition (2) is satisfied:
−30<fR/fF<−11 (2),
wherein
fR designates the focal length of said negative rear lens group, and
fF designates the focal length of said positive front lens group.

### Claim 3 (depends on 1)

The superwide-angle lens system according to claim 1, wherein said positive front lens group includes at least two negative single lens elements which are consecutively provided from a position closest to the object side.

### Claim 4 (depends on 3)

The superwide-angle lens system according to claim 3, wherein the following condition (3) is satisfied:
−2.0<fn/fF<−1.3 (3),
wherein
fn designates the combined focal length of said at least two negative single lens elements which are consecutively provided from the position closest to the object side within said positive front lens group, and
fF designates the focal length of said positive front lens group.

### Claim 5 (depends on 1)

The superwide-angle lens system according to claim 1, wherein said negative rear lens group comprises a cemented lens provided with one negative lens element and one positive lens element.

### Claim 6 (depends on 1)

The superwide-angle lens system according to claim 1, wherein the following condition (4) is satisfied:
20<νd<35 (4),
wherein
νd designates the Abbe number with respect to the d-line of the positive lens element provided closest to the object side within said positive front lens group.