Zoom lens system

Abstract

A zoom lens system includes a negative first lens group, a variable diaphragm, a positive second lens group, in this order from the object. Zooming is performed by moving the negative first lens group and the positive second lens group. The negative first lens group is constituted by at least two negative lens elements and at least two positive lens elements. The zoom lens system satisfies the following conditions: 1.5<|f1/fw|<1.8  (1) 1.0<|f2/(fw×ft)1/2<1.3  (2) 1.0<|f2/f1|<1.2  (3) wherein f1 designates the focal length of the negative first lens group; f2 designates the focal length of the positive second lens group; fw designates the focal length of the entire the zoom lens system at the short focal length extremity; and ft designates the focal length of the entire the zoom lens system at the long focal length extremity.

Dependencies are inferred from the claim text.