Patent ID: 7697221

Claim:
An imaging lens comprising, in order from an object side: a first lens that is a negative lens having a meniscus shape with a convex surface directed to the object side; a second lens that is a negative lens; a third lens that is a positive lens having a convex surface directed to the object side; an aperture stop; and a fourth lens that is a biconvex lens, wherein the following conditional expression is satisfied: 2.111 <f 4 /fa≦ 2.7 (1) where fa denotes a focal length of the whole lens system, and f 4 denotes a focal length of the fourth lens; and wherein the following conditional expression is satisfied: −3.0<( r 3+ r 4)/( r 3− r 4)<0.2 (3A) where r 3 denotes a curvature radius of an object-side surface of the second lens, and r 4 denotes a curvature radius of an image-side surface of the second lens.