Patent ID: 7667898

Claim:
A zoom lens, comprising: a first lens group having negative power, a second lens group having positive power, a third lens group having positive power, and a fourth lens group having positive power, disposed in this order from the enlargement side, wherein at the time of zooming from the wide angle side to the telephoto side, the first lens group shifts from the enlargement side to the reduction side and the second and third lens groups shift from the reduction side to the enlargement side and the fourth lens group is fixed, the overall length of the zoom lens becomes a maximum at the wide angle end, the second lens group consists of one positive lens having a convex surface on the enlargement side, and assuming that the focal length of the entire system at the wide angle end is Fw and that the focal length of the second lens group is F2, the second lens group satisfies the following conditional expression: 0.1 <|Fw/F 2|<0.35.