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:
Dec. 07, 1999
Filed:
Dec. 03, 1998
William T 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, a middle lens unit of positive refractive power, and a rear lens unit of negative refractive power. The front lens unit has a positive lens element and a negative lens element airspaced from the positive lens element. During zooming from a wide-angle to a telephoto position, the front and the rear lens units simultaneously move the toward an object side. The middle lens unit also moves toward the object side, but by a shorter net axial distance than the distance traveled by the front and rear lens units. The 'net axial distance' refers to the axial distance between one zoom and another zoom position of a lens unit. 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 >2.5, where L.sub.v is the distance from the front vertex of the zoom lens to the film plane in the telephoto position, f.sub.t is the focal length of the zoom lens in the telephoto position, and f.sub.w is the focal length of the zoom lens in the wide-angle position.