Zoom Lens System, Interchangeable Lens Apparatus and Camera System

• US 20120162779A1
• Filed: 12/22/2011
• Published: 06/28/2012
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Imaoka, Takuya
• Granted Patent: US 8,743,471 B2
• Time in Patent Office: Days
• US Class Current: 359/684
• CPC Class Codes: G02B 15/144511 arranged -+-+
• CPC Class Codes: 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

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 first lens unit moves along an optical axis, and 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, and the condition: 0.8<|f_I/f_W|<1.4 (f_I: a composite focal length of the first lens unit, f_W: a focal length of the entire system at a wide-angle limit) is satisfied; an interchangeable lens apparatus; and a camera system are provided.

Claims

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 first lens unit moves along an optical axis, and 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, and

the following condition (1) is satisfied:

0.8<

f_I/f_W|<

1.4 

 

(1)

where

f_I is a composite focal length of the first lens unit, and

f_W is a focal length of the entire system at a wide-angle limit.

2. The zoom lens system as claimed in claim 1, wherein

the following condition (2) is satisfied:

0.30<

d_I/f_W<

0.85 

 

(2)

where

d_I is an optical axial thickness of the first lens unit, and

f_W is a focal length of the entire system at a wide-angle limit.

3. The zoom lens system as claimed in claim 1, wherein

the following condition (3) is satisfied:

0.7<

f₂/f_W<

1.2 

 

(3)

where

f₂ is a composite focal length of the second lens unit, and

f_W is a focal length of the entire system at a wide-angle limit.

4. The zoom lens system as claimed in claim 1, wherein

the third lens unit moves along the optical axis in focusing from an infinity in-focus condition to a close-object in-focus condition.

5. 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.

6. 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.