Zoom lens system

摘要

A zoom lens system which includes a positive first lens group and a negative second lens group, arranged in this order from an object side so that a distance between the first and second lens groups is changed to alter the focal length. The first lens group includes a first negative sub-lens group, and a first positive sub-lens group. The first negative sub-lens group includes a first negative lens made of glass, and a second negative lens made of plastic. The first positive sub-lens group includes a positive third lens made of glass. The negative second lens group includes a positive fourth lens made of plastic, and a negative fifth lens made of glass lens, in this order from the object side. The zoom lens system satisfies the following relationships:SF1=(r1-1+r1-2)/(r1-1-r1-2)0where SF1 designates the shaping factor of the first negative lens, SF2 the shaping factor of the second negative lens, and r1-j the radius of curvature of the j-th surface of the i-th lens, respectively.