Patent ID: 8243371
Filing Date: 2012-08-14
Classification: G02B

Abstract:
1. A high zoom-ratio zoom lens system comprising a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth 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 the first through fourth lens groups are moved along the optical axis direction, wherein an amount of movement of said first lens group along the optical axis direction is greater than that of said third lens group, and wherein the following conditions (1) and (2) are satisfied: wherein FT designates the entire focal length at the long focal length extremity, F1 designates the focal length of the first lens group, M2T designates the magnification of the second lens group with respect to an object at infinity at the long focal length extremity, and M2W designates the magnification of the second lens group with respect to an object at infinity at the short focal length extremity.