Patent ID: 8817390

Claim:
An image pickup lens comprising, in order from an object side to an image plane side: an aperture stop; a first lens of a biconvex shape having a positive refractive power with convex surfaces facing both the object side and the image side near an optical axis; a second lens of a meniscus shape having a negative refractive power with a concave surface facing the object side near the optical axis; a third lens of a meniscus shape having a positive refractive power with a concave surface facing the object side near the optical axis; and a fourth lens of a biconcave shape having a negative refractive power with concave surfaces facing both the object side and the image side near the optical axis; wherein the image pickup lens satisfies following conditional expressions (1) and (4): 0.6< f 1 / f <0.8 (1) 0.7<| f 2|/ f <1.2 (4) where f 1 represents a focal length of the first lens, f 2 represents a focal length of the second lens, and f represents a focal length of an overall optical system of the image pickup lens, and wherein none of the first lens, the second lens, the third lens, and the fourth lens are in contact with each other.