Patent ID: 8462438
Filing Date: 2013-06-11
Classification: G02B

Abstract:
1. A lens for projection substantially consisting of: a first lens group; and a second lens group, which are arranged in this order from the magnification side of the lens for projection, wherein the lens for projection is composed of seven lenses, and wherein the reduction side of the lens for projection is telecentric, and wherein the first lens group is composed of two lenses including at least one negative lens, and wherein the second lens group is composed of a positive second-group first lens having a convex surface facing the magnification side, a negative second-group second lens having a concave surface facing the magnification side, a positive second-group third lens having a convex surface facing the reduction side of the lens for projection, a positive second-group fourth lens, and a positive second-group fifth lens, which are arranged in this order from the magnification side, and wherein a space is provided between a reduction-side surface of the second-group second lens and a magnification-side surface of the second-group third lens, and wherein the following formulas (A) and (B) are satisfied: where Bf is a back focus in air of an entire lens system, f is the focal length of the entire lens system, and f23 is the focal length of an air lens formed between the reduction-side surface of the second-group second lens and the magnification-side surface of the second-group third lens.