Title:
RETRO-FOCUS TYPE LENS
Document Type and Number:
Japanese Patent JPH04174808
Kind Code:
A
Abstract:
PURPOSE:To obtain a high optical performance image with aberrations such as distortion aberration and flare corrected properly by providing a meniscus shaped aspherical lens which has an aspherical shape in the third part system and whose recessed surface faces the second conjugate point side. CONSTITUTION:When a plurality of lenses are divided into three groups, the first part system I, second part system II and third part system III, in the order from the first conjugate point side of long distance, and the focal distance of a total system is taken as fT, back focus SK is set so as to be SK>0.7fT, and at least one meniscus shaped aspherical lens (the 31st aspherical lens), the surface of at least one side of which is aspheric and, which has an aspheric shape, whose thickness measured in the direction of an optical axis increases within an effective diameter as it separates from the optical axis, and whose recessed surface faces the second conjugate point side, is arranged in the third part system III. By thus setting lens constitution, a high optical performance projected image with aberrations such as distortion aberration and flare corrected properly can be obtained.
Inventors:
HAYAKAWA SHINGO
YAMAZAKI SHOICHI
YANO KOTARO
KITAGISHI NOZOMI
YAMAZAKI SHOICHI
YANO KOTARO
KITAGISHI NOZOMI
Application Number:
JP30300790A
Publication Date:
June 23, 1992
Filing Date:
November 08, 1990
Export Citation:
Assignee:
CANON KK
International Classes:
G02B13/04; G02B13/18; (IPC1-7): G02B13/04; G02B13/18
Domestic Patent References:
| JP44012393A | ||||
| JPS6410206A | 1989-01-13 | |||
| JPH02228620A | 1990-09-11 |
Attorney, Agent or Firm:
Takanashi Yukio