# US 8,786,958 B2 · Zoom lens system, interchangeable lens apparatus and camera system

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- Number: US 8,786,958 B2
- Document ID: US8786958B2
- Status: Granted
- Kind: B2
- Application number: 13/334,071
- Filed: 2011-12-22
- Published: 2012-06-28
- Granted: 2014-07-22
- Earliest claimed: 2010-12-22
- Assignees: Panasonic Corporation
- Applicants: Takuya Imaoka
- Inventors: Takuya Imaoka
- Web page: https://patentgrep.com/patent/US8786958B2

## CPC

- 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 15/144511: {arranged -+-+}
- G02B 15/177: having a negative front lens or group of lenses
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A zoom lens system, in order from an object side to an image side, comprising a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having negative optical power, and a fourth lens unit having positive optical power, wherein the third lens unit moves along an optical axis in focusing from an infinity in-focus condition to a close-object in-focus condition, and the conditions: 0.5<|f3/fW|<2.0 and 0.005<d3/fW<0.070 (f3: a focal length of the third lens unit, d3: an optical axial thickness of the third lens unit, fW: a focal length of the entire system at a wide-angle limit) are satisfied; an interchangeable lens apparatus; and a camera system are provided.

## Claims

### Claim 1

A zoom lens system, in order from an object side to an image side, comprising a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having negative optical power, and a fourth lens unit having positive optical power, wherein
the third lens unit moves along an optical axis in focusing from an infinity in-focus condition to a close-object in-focus condition, and
the following conditions (1) and (2) are satisfied:
0.5<|f3/fW|<2.0 (1)
0.005<d3/fW<0.070 (2)
where
f3 is a focal length of the third lens unit,
d3 is an optical axial thickness of the third lens unit, and
fW is a focal length of the entire system at a wide-angle limit.

### Claim 2 (depends on 1)

The zoom lens system as claimed in claim 1, wherein
the following condition (3) is satisfied:
0.30<d1/fW<0.85 (3)
where
d1 is an optical axial thickness of the first lens unit, and
fW is a focal length of the entire system at a wide-angle limit.

### Claim 3 (depends on 1)

The zoom lens system as claimed in claim 1, wherein
the fourth lens unit is fixed relative to an image surface in zooming from a wide-angle limit to a telephoto limit at the time of image taking.

### Claim 4 (depends on 1)

The zoom lens system as claimed in claim 1, wherein
the first lens unit moves along the optical axis in zooming from a wide-angle limit to a telephoto limit at the time of image taking.

### Claim 5 (depends on 1)

An interchangeable lens apparatus comprising:
a zoom lens system as claimed in claim 1; and
a lens mount section which is connectable to a camera body including an image sensor for receiving an optical image formed by the zoom lens system and converting the optical image into an electric image signal.

### Claim 6 (depends on 1)

A camera system comprising:
an interchangeable lens apparatus including a zoom lens system as claimed in claim 1; and
a camera body which is detachably connected to the interchangeable lens apparatus via a camera mount section, and includes an image sensor for receiving an optical image formed by the zoom lens system and converting the optical image into an electric image signal.