Patent ID: 7830614
Filing Date: 2010-11-09
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, each of said negative first lens group, said positive second lens group and said positive third lens group moves along the optical axis; wherein said negative first lens group comprises a negative first sub-lens element, a second sub-lens element having a weak negative refractive power and at least one aspherical surface, and a positive third sub-lens element, in this order from the object; and wherein said zoom lens system satisfies the following condition: wherein ra designates the radius of curvature of the object-side surface of said second sub-lens element of said negative first lens group; and rb designates the radius of curvature of the image-side surface of said second sub-lens element of said negative first lens group; and said negative first lens group satisfies the following condition: wherein ν1−3 designates the Abbe number of said positive third sub-lens element of said negative first lens group.