Patent ID: 8054560
Filing Date: 2011-11-08
Classification: G02B

Abstract:
1. A zoom lens, comprising: a first lens group with positive refractive power fixed at a predetermined position; a second lens group with negative refractive power being movable along an optical axis of the zoom lens in accordance with the change of the magnification of the zoom lens; a third lens group with positive refractive power having at least one lens that is fixed at a predetermined position; and a fourth lens group with positive refractive power being movable along the optical axis in order to keep an image plane generated by the zoom lens to be projected accurately onto an image sensor; wherein the first, the second, the third and the fourth lens groups are arranged along the optical axis and from an object side of the zoom lens to an image side of the zoom lens in sequence, and the first, the second, the third and the fourth lens groups conform to the following conditions: wherein F1 is the focal length of the first lens group, F2 is the focal length of the second lens group, F3 is the focal length of the third lens group, F4 is the focal length of the fourth lens group, FW is the focal length at wide-configuration, and FT is the focal length at tele-configuration.