Patent ID: 7463425

Claim:
A zoom lens system comprising: a front first lens group including a first lens of divergent meniscus and a second lens of plano-convex; an intermediate second lens group including a third lens of plano-concave, a fourth lens of plano-concave, and a fifth lens of plano-convex; and a rear third lens group including a sixth lens of double-convex, a seventh lens of double-convex, an eighth lens of plano-concave, and a ninth lens of plano-concave, wherein the sixth and the ninth lenses are non-spherical lenses formed of a plastic material, and the zoom lens system satisfies the following conditions (a)-(d): 0.16 <f w /f 1 <0.21 (a) −0.78 <f w /f 2 <−0.64 (b) 0.70 <f w /f 3 <0.75 (c) 0.47<log Z 3 /log Z< 0.76 (d) where f w is a focal length of the overall system at a wide angle end, f 1 is a focal length of the first lens group, f 2 is a focal length of the second lens group, f 3 is a focal length of the third lens group, Z is the change ratio of magnification of the overall system, Z 3 is a change ratio (Z 3 =m3t/m3w) of magnification of the third lens group, m3t is a lateral magnification of the third lens group at a telescopic end, and m3w is a lateral magnification of the third lens group at a wide angle end.