Patent ID: 6094314
Filing Date: 2000-07-25
Classification: G02B

Abstract:
A zoom lens system which, in order from an object side of said zoom lens system, comprises at least a negative lens group and a first positive lens group and further includes a second positive lens group located between said first positive lens group and an image side of said zoom lens system and including at least one surface having diffractive action substantially rotationally symmetric with respect to an optical axis of said zoom lens system, and in which at least a spacing between said negative lens group and said first positive lens group is varied for zoomingwherein said zoom lens system satisfies the following conditions (1) and (2):0.02.ltoreq.f.sub.3 /(.nu..sub.2 f.sub.2).ltoreq.0.4 (1)-25.ltoreq..nu..sub.1 -.nu..sub.2 .ltoreq.20 (2)where f.sub.2 is a focal length of said first positive lens group, f.sub.3 is a focal length of said surface having diffractive action, .nu..sub.1 is an equivalent Abbe number of said negative lens group, and .nu..sub.2 is an equivalent Abbe number of said first positive lens group.