Patent ID: 8315000

Claim:
An image pickup lens for forming an image onto a photoelectric conversion section of a solid-state image pickup element, the image pickup lens comprising, in order from an object side thereof: an aperture stop; a first lens with a positive refractive power; a second lens with a negative refractive power; a third lens with a positive refractive power; and a fourth lens with a negative refractive power whose object-side surface is a convex surface, wherein the image pickup lens satisfies the following conditional expressions (1) and (2): 0.29≦( r 1 +r 2)/( r 1 −r 2)<0.9 (1) 0.80<( r 3 +r 4)/( r 3 −r 4)<5.1 (2) where r1 is a curvature radius of an object-side surface of the first lens, r2 is a curvature radius of an image-side surface of the first lens, r3 is a curvature radius of the object-side surface of the second lens, and r4 is a curvature radius of an image-side surface of the second lens.