Patent ID: 8441736

Claim:
A lens for projection substantially consisting of five lenses, wherein a negative first lens having a concave surface facing the reduction side of the lens for projection, a positive second lens having a convex surface facing the magnification side of the lens for projection, a negative third lens having a concave surface facing the magnification side, a positive fourth lens having a convex surface facing the reduction side, and a positive fifth lens are arranged in this order from the magnification side, and wherein the following formulas (A) through (D) are satisfied at the same time: 1.2≦ Bf/f≦ 2.5 (A); −3.0 f 3 F/f− 0.8 (B); 1.4≦ f 5 F/f 5≦8.5 (C); and 1.0 ≦d 12/ f≦ 2.7 (D), where Bf is a back focus in air of the entire system of the lens for projection, f is the focal length of the entire system of the lens for projection, f3F is the focal length of a magnification-side surface of the third lens, f5F is the focal length of a magnification-side surface of the fifth lens, f5 is the focal length of the fifth lens, and d12 is an air space between the first lens and the second lens.