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:
Sep. 05, 1995
Filed:
Jul. 09, 1993
Koichi Maruyama, Tokyo, JP;
Jun Hirakawa, Tokyo, JP;
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
A telephoto zoom lens system is disclosed in which the wide-angle end starts with the middle telephoto range and in which focusing is done by means of a lighter focusing lens group than what is used in the method of focusing by advancing the front lens component and that only small aberrational variations occur even if zooming is done up to the closest focusing distance. The telephoto zoom lens system includes a front lens component and a rear lens component, said front lens component comprising a front lens group and having, in order from the object side, a positive first sub-group 1a and a positive second sub-group 1b and having an overall positive power. The first sub-group 1a is such that a negative meniscus lens having a convex surface directed towards the object is located closest to the image plane, and the rear lens component is located closer to the image plane than the front lens component and having a zooming capability, focusing for the object being effected by moving only the second sub-group 1b towards the object when it is positioned at near distance.