Title:
ズームレンズ
Document Type and Number:
Japanese Patent JP4432153
Kind Code:
B2
Abstract:
The present invention makes it possible to provide a variable focal length lens system having a zoom ratio of 2.5 or over, a field angle of 60° or over at the wide-angle end, and an excellent imaging quality which is suited for use with a video camera and the like. According to one aspect of the present invention, a variable focal length lens system has, in order from an object side, a first negative lens group G1, a second positive lens group G2, and a third positive lens group G3. The first lens group includes, in order from the object side, a negative lens unit 1-1 U11 and a positive lens unit 1-2 U12 separated by predetermined air space; and the second lens group includes, in order from the object side, a positive lens unit 2-1 U21, a negative lens unit 2-2 U22 separated by predetermined air space, and a positive lens unit 2-3 U23 separated by predetermined air space, with the first and second lens groups being moved such that when a state of the lens group positions is changed from a wide-angle end state to a telephoto end state, a space between the first and second lens group is decreased and a space between the second and third lens groups is increased while the third lens group is fixed, and further with designated conditional equations being satisfied.
Inventors:
Atsushi Shibayama
Application Number:
JP22000099A
Publication Date:
March 17, 2010
Filing Date:
August 03, 1999
Export Citation:
Assignee:
NIKON CORPORATION
International Classes:
G02B15/163; G02B15/20; G02B13/18; G02B15/177
Domestic Patent References:
| JP1039214A | ||||
| JP1152246A | ||||
| JP921950A | ||||
| JP62200316A |
Attorney, Agent or Firm:
Yoshio Inoue
Mitsuhiro Fukuda
Mitsuhiro Fukuda