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:
Mar. 23, 1999
Filed:
Jul. 28, 1997
William Thomas Goosey, Jr, Fairport, NY (US);
Eastman Kodak Company, Rochester, NY (US);
Abstract
The zoom lens according to the present invention comprises three lens units. More specifically, there is a front lens unit of positive refractive power consisting of a positive lens element and a negative lens element, a middle lens unit of positive refractive power, and a rear lens unit of negative refractive power. During zooming from a wide-angle to a telephoto position, the front lens unit and the rear lens unit simultaneously movable towards an object side during zooming from a wide angle to a telephoto position. The middle lens unit moves towards the object side at a relatively slower speed than that at which the front and the rear lens units are moved. The lens elements have sufficient optical powers, spacings and radii of curvature to provide for a large zoom ratio ZR and to maintain an overall compactness so that L.sub.v /f.sub.t <0.9 and ZR=f.sub.t /f.sub.w >2.3, where L.sub.v is the distance from the front vertex of the lens system to the film plane in the telephoto position, f.sub.t is the focal length of the lens system in the telephoto position, and f.sub.w is the focal length of the zoom lens system in the wide-angle position. At least one lens element comprising the middle or the rear lens unit has a V-number greater than 70. According to a preferred embodiment, this V-number is greater than 80. Also, according to a preferred embodiment the front and the rear lens units are integral so as to be simultaneously movable for zooming at the same speed and direction.