Patent ID: 8279530

Claim:
A zoom lens system for imaging an object to an image plane, the zoom lens system, in the order from the object side to the image plane thereof, comprising: a first lens group with positive refraction power; a second lens group with negative refraction power; a third lens group with positive refraction power; an aperture stop; a fourth lens group with positive refraction power; and a fifth lens group with negative refraction power comprising a lens of negative refraction power and a lens positive refraction power; wherein the first lens group, the third lens group, and the fifth lens group are immovably positioned along the optical axial of the zoom lens system, the second lens group and the fourth lens group are capable of sliding along the optical axis of the zoom lens system, the zoom lens system satisfies the formulas: −0.18 <f 2 /ft< −0.13; and V 11 −V 12<20; wherein, f2 is the effective focal length of the second lens group, ft is the effective focal length of the zoom lens system in the telescopic state, V11 is the Abbe number of the lens of negative refraction power of the fifth lens group, V12 is the Abbe number the lens of positive refraction power of the fifth lens group.