Patent ID: 7042652
Filing Date: 2006-05-09
Classification: G02B

Abstract:
1. A zoom lens system for forming an optical image of a subject on an image-sensing surface of an image sensor, wherein the zoom lens system comprises three lens units, namely, from an object side thereof, a first lens unit having a negative optical power, a second lens unit having a positive optical power, and a third lens unit having a positive optical power, wherein the zoom lens system achieves zooming by varying distances between the individual lens units in such a way that, during zooming from a wide-angle end to a telephoto end, a distance between the first and second lens units decreases, wherein the first lens unit comprises two or more lens elements, wherein a first lens element, i.e., a lens element disposed at an object-side end of the first lens unit, and a last lens element, i.e., a lens element disposed at an image-side end of the third lens unit, are plastic lens elements, and wherein the following conditional formula (1) is fulfilled: where fl fw represents a focal length of the zoom lens system as a whole at the wide-angle end.