Patent ID: 8730594

Claim:
An image pickup lens for a solid-state image pickup element, comprising, in order from an object side, a first lens having a positive refractive power with a convex surface facing the object side in the vicinity of an optical axis, a second lens of a biconcave lens shape facing concave surfaces to the object side and an image side in the vicinity of the optical axis, a third lens of a meniscus shape having a positive refractive power with a convex surface facing the image side in the vicinity of the optical axis, and a fourth lens of a biconcave lens shape facing concave surfaces to the object side and the image side in the vicinity of the optical axis, wherein the image pickup lens satisfies the following conditional expressions (1), (2), (4), (5), (7), and (8): −1.3< r 1/ r 2<0.03 (1) 0.09< r 6/ r 5<1.0 (2) −0.52644≦ f 4/ f< −0.35 (4) −0.16270≦ r 8/ r 7≦−0.0049871 (5) 0.38659694≦ f 3/ f≦ 0.565293 (7) −2.0< r 4/ r 3≦−0.02195 (8) where r 1 : a curvature radius of the object side surface of the first lens; r 2 : a curvature radius of the image side surface of the first lens; r 3 : a curvature radius of the object side surface of the second lens; r 4 : a curvature radius of the image side surface of the second lens; r 5 : a curvature radius of the object side surface of the third lens; r 6 : a curvature radius of the image side surface of the third lens; r 7 : a curvature radius of the object side surface of the fourth lens; r 8 : a curvature radius of the image side surface of the fourth lens; f: a composite focal length of an overall image pickup lens system; f 3 : a focal length of the third lens; and f 4 : a focal length of the fourth lens.