Patent ID: 6429979
Filing Date: 2002-08-06
Classification: G02B

Abstract:
A zoom lens system comprising a positive first lens group and a negative second lens group, in this order from an object,wherein one of said first lens group and said second lens group comprises a switching lens group, and said switching lens group comprises at least two sub-lens groups; wherein one sub-lens group is made moveable, with respect to other sub-lens groups, to either the object-side end or the image-side end; wherein in a short-focal-length side zooming range from the short focal length extremity to an intermediate switching focal length, said first lens group and said second lens group are moved towards said object, and the distance therebetween is varied, while said moveable sub-lens group in said switching lens group is being made stationary at the object-side end; wherein at said intermediate switching focal length, said moveable sub-lens group is moved to the image-side end, and said first lens group and said second lens group are moved towards the image plane; wherein in a long-focal-length side zooming range from said intermediate switching focal length to the long focal length extremity, said first lens group and said second lens group are moved towards said object, and the distance therebetween is varied, while said moveable sub-lens group in said switching lens group is being made stationary at the image-side end; and wherein said zoom lens system satisfies the following condition: 0.3whereinZi=fm/fw; Z=ft/fw; fw designates the focal length at the short focal length extremity; ft designates the focal length at the long focal length extremity; and fm designates said intermediate switching focal length.