Patent ID: 7911705

Claim:
A projection lens comprising at least two movable lens groups constructed to be moved in zooming, wherein one of the movable lens groups having a maximum moving amount includes at least one positive lens element having a positive power, the movable lens group having the maximum moving amount is arranged on an enlargement side with respect to a diaphragm, and is operable to move toward the diaphragm in zooming from a telephoto end to a wide-angle end, and the movable lens group having the maximum moving amount and the positive lens element satisfy the following conditional expressions (1) through (3) Pg,F+ 0.00181 Vd> 0.652 (1) 0.5 <Lr/L< 0.8 (2) 1.2 <Lsf/Lsr< 5 (3) where Pg, F: a partial dispersion ratio of a lens glass material of the positive lens element, Vd: an Abbe number of the lens glass material of the positive lens element, Lr: a distance between an apex of a reduction-side lens surface in the movable lens group having the maximum moving amount, and an apex of a reduction-side lens surface in all the lens groups, in the case where the movable lens group having the maximum moving amount is moved to a position closest to the enlargement side in zooming, L: a lens length of all the lens groups, in the case where the movable lens group having the maximum moving amount is moved to the position closest to the enlargement side in zooming, Lsf: a distance between the apex of the reduction-side lens surface in the movable lens group having the maximum moving amount, and a surface of the diaphragm, in the case where the movable lens group having the maximum moving amount is moved to the position closest to the enlargement side in zooming, and Lsr: a distance between the apex of the reduction-side lens surface in the movable lens group having the maximum moving amount, and the surface of the diaphragm, in the case where the movable lens group having the maximum moving amount is moved to a position closest to a reduction side in zooming.