The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 15, 1992
Filed:
Apr. 14, 1992
Applicant:
Inventor:
Jun Hirakawa, Tokyo, JP;
Assignee:
Asahi Kogaku Kogyo K.K., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G02B / ;
U.S. Cl.
CPC ...
359745 ; 359746 ;
Abstract
A large aperture, medium telephoto lens system is disclosed which is composed of a front group G.sub.F that comprises, in order from the object side, at least two positive lens elements having a strong convex surface directed toward the object and a negative lens having a strong concave surface directed toward the image and which has a positive overall refractive power, and a rear group G.sub.R with a surface S.sub.R1 which is the closest to the object being convex toward the object and which the a positive overall refractive power, with only the rear group G.sub.R being moved along the optical axis to perform focusing operations.