Patent ID: 7215484

Claim:
A zoom lens system comprising, in the order from an object side: (a) a first lens group which has a negative refractive power; (b) a second lens group which has a positive refractive power; and (c) a third lens group which has a positive refractive power in the order from the object side, wherein power of the zoom lens system is varied from a wide-angle end to a telephoto end by changing distances among the lens groups, wherein the second lens group has a three-element cemented lens and at least one negative lens, the three-element cemented lens comprising a positive lens c 1 , a negative lens c 2 , and a positive lens c 3 in the order from the object side, and wherein the three-element cemented lens satisfies the following conditional expressions: 0.05< n c3 −n c2 5<ν c3 −ν c2 where n c2 represents refractive index of the lens c 2 , n c3 represents refractive index of the lens c 3 , ν c2 represents Abbe's number of the lens c 2 , and ν c3 represents Abbe's number of the lens c 3 .