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:
Jun. 14, 2005
Filed:
Jul. 07, 2003
Nobutaka Minefuji, Saitama, JP;
Nobutaka Minefuji, Saitama, JP;
PENTAX Corporation, Tokyo, JP;
Abstract
A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. The negative first lens group includes a negative meniscus lens element having the convex surface facing toward the object, and the positive third lens group includes a positive biconvex lens element. Upon zooming, at least the negative first lens group and the positive second lens group are moved. A diaphragm is provided on the object side of the positive second lens group, and moves integrally therewith. The zoom lens system satisfies the following conditions: 0.25<R/D<0.55 . . . (1); 0.25<f/TL<0.45 . . . (2) wherein R: the radius of curvature of the image-side surface of the negative meniscus lens element; D: the distance between the negative first lens group and the positive second lens group at the short focal length extremity; f: the focal length of the positive second lens group; and TL: the distance from the most object-side surface the negative first lens group to the most image-side surface of the positive third lens group, at the short focal length extremity.