Patent ID: 7777965
Filing Date: 2010-08-17
Classification: G02B

Abstract:
1. 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 an object, wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between said negative first lens group and said positive second lens group decreases, and the distance between said positive second lens group and said positive third lens group increases; wherein said negative first lens group comprises a negative first lens element, a positive or negative second lens element having a weaker refractive power, and a positive third lens element, in this order from the object; wherein said zoom lens system satisfied the following condition: wherein f1 designates the focal length of said negative first lens group; and fp designates the focal length of said second lens element; wherein said positive third lens group is arranged to function as a focusing lens group, and comprises a biconvex plastic lens element having at least one aspherical surface; and wherein said zoom lens system satisfies the following conditions: wherein f2 designates the focal length of said positive second lens group; rs designates a radius of curvature of the most image-side surface of said positive second lens group; and f3 designates the focal length of said positive third lens group.