Patent ID: 7466494

Claim:
A zoom lens consisting of, in order from an enlargement side to a reduction side, a first lens group of negative refractive power disposed adjacent to the enlargement side, a second lens group of positive refractive power disposed adjacent to the reduction side, and an aperture stop, both the first and second lens groups being movable, the first and second lens groups defining a variable distance therebetween; wherein, during zooming from the wide-angle end to the telephoto end, the second lens group moves toward the enlargement side and the variable distance between the first and second lens groups decreases; and wherein the zoom lens satisfies the following condition: 0.649 <  lt tt  < 0.723 where lt represents the overall length from a front vertex of the first lens element to a rear vertex of the last lens element of the zoom lens at the wide-angle end, and tt represents the total optical track of the zoom lens at the wide-angle end.