Patent ID: 6768595
Filing Date: 2004-07-27
Classification: G02B

Abstract:
A zoom lens formed of only five lens groups, in order from the enlarging side, as follows:a negative first lens group that is movable for focusing and that is stationary during zooming; a positive second lens group; a positive third lens group; a negative fourth lens group; a positive fifth lens group that is stationary during zooming; whereinsaid positive second lens group includes a negative lens component; said positive second lens group, said positive third lens group, and said negative fourth lens group move relative to one another and relative to said negative first lens group and said positive fifth lens group during zooming; and the follow conditions are satisfied: âˆ’1.21/f0.9 0.92/f<1.5 1.03/f<1.5 1.05/f<1.5 wheref1 is the focal length of said first lens group; f is the focal length of the zoom lens at the wide-angle end; f2 is the focal length of said second lens group; f3 is the focal length of said third lens group; and f5 is the focal length of said fifth lens group.