Patent ID: 7538953

Claim:
A zoom lens system comprises a negative first lens group, a positive second lens group, and a positive third lens group, in this order from the object, wherein each of said negative first lens group, said positive second lens group and said positive third lens group is moved along the optical axis to perform zooming; wherein said negative first lens group comprises a negative lens element, a negative lens element and a positive lens element, in this order from the object; wherein said positive second lens group comprises a positive lens element, a positive lens element and a negative lens element, in this order from the object, a combined refractive power of said image-side positive lens element and said negative lens element is negative, and said image-side positive lens element and said negative lens element are cemented to each other; wherein said positive third lens group comprises a positive lens element and a negative lens element which are cemented to each other, in this order from the object; and wherein said zoom lens system satisfies the following condition: 1.2< f 2G /f 21 <2.0 wherein f 2G designates a focal length of said positive second lens group; and f 21 designates a focal length of the most object-side positive lens element in said positive second lens group.