Patent ID: 6212017
Filing Date: 2001-04-03
Classification: G02B

Abstract:
A soft-focus zoom lens system comprising a positive front lens group, a negative intermediate lens group, and a positive rear lens group, in this order from an object;wherein zooming is performed by respectively moving said front lens group, said intermediate lens group, and said rear lens group, along the optical axis; andwherein said zoom lens system satisfies the following conditions:SAU/fw<-0.100.30<D.sub.23w /fw0.25<D.sub.12t /ftwhereinSAU designates the amount of spherical aberration at an open aperture, with respect to a focal length at which the amount of spherical aberration, upon zooming, becomes the smallest;fw designates the focal length of the entire lens system at the short focal length extremity;D.sub.23w designates the axial distance, at the short focal length extremity, between the most image-side surface of said intermediate lens group and the most object-side surface of said rear lens group;D.sub.12t designates the axial distance, at the long focal length extremity, between the most image-side surface of said front lens group and the most object-side surface of said intermediate lens group; andft designates the focal length of the entire zoom lens system at the long focal length extremity.