Patent ID: 8085476

Claim:
A zoom lens system comprising: a first lens unit having a negative optical power; a second lens unit having a positive optical power, the second lens unit having a plurality of lenses, wherein distances between the lenses of the second lens unit are constant during zooming; and a third lens unit having a negative optical power, wherein the first, second, and third lens units being disposed in order from the object side to the image side of the zoom lens system, wherein a distance between the first and second lens units and a distance between the second and third lens units changes during a zooming process of the zoom lens system, and wherein 0.40 <Z 3 /Z 2<0.82, −0.67 <fW/f 3<−0.53, and −0.9 <f 2 /f 3≦−0.644 are satisfied, where Z 2=β2 T/β 2 W Z 3=β3 T/β 3 W β 2 T represents the imaging magnification of the second lens unit at the telephoto end, β 2 W represents the imaging magnification of the second lens unit at the wide-angle end, β 3 T represent the imaging magnification of the third lens unit at the telephoto end, β 3 W represents the imaging magnification of the third lens unit at the wide-angle end, fW represents the focal length of the overall zoom lens system at the wide-angle end, f 3 represents the focal length of the third lens unit, and f 2 represents the focal length of the second lens unit, and wherein the first, second and third lens units are moved during the zooming process of the zoom lens system.