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:
Nov. 16, 1999
Filed:
Jan. 15, 1998
Applicant:
Inventors:
Fumiaki Usui, Kanagawa-ken, JP;
Kiyoshi Fukami, Kanagawa-ken, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B / ;
U.S. Cl.
CPC ...
359684 ; 359686 ; 359676 ;
Abstract
A zoom lens is disclosed comprising, from front to rear a first lens unit of positive refractive power, a second lens unit of negative refractive power for varying the focal length, a third lens unit for compensating for the image shift with zooming, and a fourth lens unit having the image forming function and stationary during zooming, wherein the first lens unit is divided into two or three lens subunits, one of which is moved to effect focusing, and various rules of design are set forth to suppress well the variation of aberrations with focusing.