Patent ID: 6757108
Filing Date: 2004-06-29
Classification: G02B

Abstract:
A zoom lens system comprising at least two lens groups,wherein a negative first lens group is positioned at the most object-side of said zoom lens system; wherein said negative first lens group comprises a negative sub-lens group and a positive sub-lens group, in this order from an object; wherein said positive sub-lens group comprises a positive lens element and a rearmost lens element of said negative first lens group, in this order from said object; wherein said rearmost lens element comprises a plastic lens element having at least one aspherical surface; and wherein said zoom lens system satisfies the following conditions: |f1/f1B-2|<0.3 0.02<D1B-2/fw<0.2 0.001<DB1-B2/fw<0.1 wherein f1 designates the focal length of said negative first lens group; f1B-2 designates the focal length of said rearmost lens element of said negative first lens group; fw designates the focal length of the entire the zoom lens system at the short focal length extremity; D1B-2 designates the thickness of said rearmost lens element of said negative first lens group; and DB1-B2 designates the distance between said positive lens element and said rearmost lens element in said positive sub-lens group.