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:
Jul. 15, 2003
Filed:
Aug. 22, 2001
Abstract
The invention relates to a zoom lens system which is compatible with a TTL optical finder having a diagonal field angle of at least 70° at the wide-angle end and about 7 to 10 magnifications and is fast as represented by an F-number of about 2.8 at the wide-angle end. The zoom lens system comprises a first lens group G which is movable along its optical axis during zooming and has positive refracting power, a second lens group G which moves toward the image side along the optical axis during zooming from the wide-angle end to the telephoto end and has negative refracting power and rear lens groups G to G having at least two spacings variable during zooming. In particular, the focal length f of the first lens group G should meet 6<f /L<20 where L is the diagonal length of an effective image pickup surface I located in the vicinity of an image-formation plane.