Cushman, Darby & Cushman
Wide-angle zoom lens system
 A wide-angle zoom lens system consisting of a front lens group, a rear lens group and an aperture stop arranged therebetween, said front lens group comprising a first positive meniscus lens element having a convex surface on the object side, a second negative meniscus lens element having a strongly concave surface on the image side, a third positive meniscus lens element having a concave surface on the object side, a fourth biconcave lens element and a fifth biconvex lens element, and said rear lens group comprising a sixth biconvex lens element, a seventh positive meniscus lens element, an eighth positive meniscus lens element, a ninth biconcave lens element, a tenth negative meniscus lens element having a concave surface on the image side and an eleventh biconvex lens element. Said zoom lens system is so adapted as to permit changing forcal length of the entire lens system by changing the airspace reserved between said front and rear lens groups. 
Olympus Optical Co., Ltd.
G G
G02B G02B
inventional inventional
Toru
Fujii