| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection lens that is downsized, and has a small curvature of field.SOLUTION: There is provided the projection lens which comprises, in order from an enlargement side,: a positive first lens group G1; and a positive second lens group G2, and in which the first lens group G1 has a surface on a most contraction side shaped into a convex, and the second lens group G2 includes two pieces of positive single lenses with a surface small in a an absolute value of a radius of curvature directed at the contraction side. The projection lens satisfies following conditional expressions (1) to (4). |R1b/R1f|≤0.5(1), |R2b/R2f|≤0.6(2), |&Dgr;/f2|≤0.3(3) and d2/f2≤0.4(4) where R1b denotes a radius of curvature of an enlargement side surface of the first lens of the second lens group, R1f denotes a radius of curvature of a contraction side surface of a first lens of the second lens group, R2b denotes a radius of curvature of a contraction side surface of a second lens of the second lens group, R2f denotes a radius of curvature of an enlargement side surface of the second lens of the second lens group, &Dgr; denotes a distance between a last surface of the first lens group and an enlargement side focus position of the second lens group, f2 denotes a focal length of the second lens group, and d2 denotes an entire length of the second lens group. |
