Zoom lens system

Abstract

A zoom lens system includes a positive first lens group and a negative second lens group in this order from an object side. A distance between the first and second lens groups is varied during a zooming operation. The first lens group consists of a negative first sub-group and a positive second sub-group, in this order from an object side. The negative first sub-group consisting of a negative first lens element, having a concave surface facing toward the object side, and a negative second lens element, having a concave surface that faces toward an image side, in this order from the object side. The negative first sub-group being provided with at least one aspherical surface. The zoom lens system satisfies the following relationships: SF1<-34<SF2 -0.4<r.sub.1-1 /f.sub.L <-0.15 0.15<r.sub.2-2 /f.sub.L <0.32 wherein SF1 represents a shaping factor of the negative first lens element (=(r.sub.1-1 +r.sub.1-2)/(r.sub.1-1 -r.sub.1-2)), SF2 represents a shaping factor of the negative second lens element (=(r.sub.2-1 +r.sub.2-2)/(r.sub.2-1 -r.sub.2-2)), r.sub.i-j represents a radius of curvature of the j-th surface of the i-th negative lens element, and f.sub.L represents a focal length of the whole lens system at a longest focal length extremity.

Dependencies are inferred from the claim text.