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:
Oct. 06, 1981
Filed:
Feb. 27, 1980
Koichi Kobayashi, Tokyo, JP;
Sadao Okudaira, Ranzan, JP;
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
A high performance telephoto lens having a small telephoto ratio including eight lenses disposed in seven lens groups in front, intermediate and rear groups. The front lens group is composed of, in order, a positive lens having two curved surfaces with the surface of greater absolute value of curvature disposed on the object side, a positive meniscus lens having its convex surface disposed toward the object, a negative biconcave lens having the surface of greater absolute value of curvature disposed toward the image side, a positive meniscus lens having a convex surface directed toward the object. The intermediate lens groups includes two cemented lenses one of which is a negative biconcave lens disposed on the object side and a positive lens disposed on the image side. The rear lens group is composed of a negative lens with the surface of greater absolute value of curvature disposed on the object side and a positive convex lens with the surface of greater absolute value of curvature disposed on the image side. The lenses satisfy: -1.2<(r.sub.6 +r.sub.5)/(r.sub.6 -r.sub.5)<-0.7, 6.7<.vertline.f/r.sub.9 .vertline.<7.6, and - 0.5<f(-1/r.sub.14 +1/r.sub.15)<3, where r.sub.i is the radius of curvature of the i-th lens surface and f is the overall focal length.