Title:
ZOOM LENS
Document Type and Number:
Japanese Patent JP3853889
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To obtain a zoom lens where aberration is excellently corrected by the small number of lenses by changing an interval between a negative lens group and a positive lens group at the time of variable power.
SOLUTION: A second positive lens group G3 including two groups of the negative lens group G1 and the positive lens group G2 in order from the side of an object and including an optical element having a surface DOE where at least one surface has diffracting action nearly rotationally symmetrically with respect to an optical axis on the side of an image from the first positive lens group G2 is arranged, and at least the interval between the negative lens group G1 and the positive lens group G2 is changed at the time of the variable power. In this case, it is desirable to satisfy the conditional expression of 0.02≤f3/ν2f2)≤0.4 and -25≤ν1-ν2≤20 so as to excellently correct chromatic aberration. In the expression, f2 means the focal distance of the first positive lens group G2, and f3 means the focal distance of the surface having the diffracting action, ν1 means the equivalent Abbe number of the negative lens group G1 and ν2 means the equivalent Abbe number of the first positive lens group G2.
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Inventors:
Kazuyuki Tanaka
Application Number:
JP31770696A
Publication Date:
December 06, 2006
Filing Date:
November 28, 1996
Export Citation:
Assignee:
Olympus Endo Technology America Inc.
International Classes:
G02B15/16; G02B15/163; G02B15/177; (IPC1-7): G02B15/16
Domestic Patent References:
| JP8327900A | ||||
| JP10148769A |
Foreign References:
| WO1996019749A1 | ||||
| US5268790 |
Attorney, Agent or Firm:
Hiroshi Nagisawa
Ryukichi Abe
Hirukawa Masanobu
Norihiko Uchida
Hideo Sugai
Kenji Aoki
Akira Yonezawa
Ryukichi Abe
Hirukawa Masanobu
Norihiko Uchida
Hideo Sugai
Kenji Aoki
Akira Yonezawa