Patent ID: 6118593
Filing Date: 2000-09-12
Classification: G02B

Abstract:
A zoom lens comprising, in order from an object side to an image side:a first lens unit of positive optical power;a second lens unit of negative optical power arranged to move during a variation of magnification, said second lens unit consisting of, in order from the object side to the image side, a negative lens, a negative lens, a positive lens and a negative lens;a third lens unit of positive optical power, said third lens unit having a plurality of positive lenses and a negative lens; anda fourth lens unit of positive optical power arranged to move during the variation of magnification, said fourth lens unit consisting of a negative lens and a positive lens, and focusing being effected by moving said fourth lens unit,wherein the following condition is satisfied:0.25<(Fm-Fw)/(Ft-Fw)<0.45where Fm is a focal length of the entire zoom lens in a position where said fourth lens unit has moved a maximum distance during the variation of magnification with focusing on an infinitely distant object, Fw is a focal length of the entire zoom lens at a wide-angle end, and Ft is a focal length of the entire zoom lens at a telephoto end.