Title:
【発明の名称】2焦点切替レンズ系
Document Type and Number:
Japanese Patent JP2679017
Kind Code:
B2
Abstract:
The present invention provides a focal length changeable lens system which comprises a master lens group of a positive refractive power having at least one negative lens element made of a synthetic resin material; and a rear conversion lens group of a negative refractive power retractably arranged on the image side of the master lens group and having at least one positive lens element made of a synthetic resin material, in order to well compensate the change of back focal length of the lens system due to the change in temperature thereof without increasing the cost of the lens system.
Inventors:
Yoshinobu Kudo
Kazuo Kimura
Kazuo Kimura
Application Number:
JP31144886A
Publication Date:
November 19, 1997
Filing Date:
December 27, 1986
Export Citation:
Assignee:
Minolta Co., Ltd.
International Classes:
G02B9/34; G02B9/60; G02B9/16; G02B9/62; G02B9/64; G02B13/18; G02B15/08; G02B15/10; G02B15/12; (IPC1-7): G02B15/12; G02B13/18
Domestic Patent References:
| JP6117114A | ||||
| JP61279816A |