Patent ID: 8498057
Filing Date: 2013-07-30
Classification: G02B

Abstract:
1. A zoom lens system comprising a negative first lens group, a positive second lens group and a positive third lens group, in that order from the object side, wherein upon zooming from the short focal length extremity to the long focal length extremity, each of said first through third lens groups move along the optical axis of the zoom lens system so that the distance between said first lens group and said second lens group decreases, and the distance between said second lens group and said third lens group increases, wherein said first lens group consists of a negative lens element and a positive lens element, in that order from the object side, wherein said second lens group includes a cemented lens including a positive lens element and a negative lens element, and a negative lens element, in that order from the object side, and wherein the following conditions are satisfied: ft designates the focal length of the entire said zoom lens system at the long focal length extremity, f1 designates the focal length of said first lens group, and f2 designates the focal length of said second lens group.