Patent ID: 10302921

Abstract:
A zoom lens system comprises, in order from an object side to an image side: a first lens group having a positive power; a second lens group having a negative power; an aperture stop, a third lens group having a positive power; and a fourth lens group having a negative power. During zooming, a total length of the zoom lens system does not change, while a distance between each adjacent two of the lens groups changes, and the aperture stop moves along an optical axis independently of the second lens group and the third lens group. The zoom lens system satisfies condition (1) 6.0<f1/fw<20.0 and condition (2) 0.5<|f4|/fw<4.0, where f1 is a focal length of the first lens group, f4 is a focal length of the fourth lens group, and fw is a focal length of the zoom lens system at a wide-angle limit.