Patent ID: 7995292

Claim:
An image pickup lens comprising, in order from an object side: a first lens element having a positive refractive power and a convex surface facing the object side; an aperture stop adjusting the amount of light; a second lens element having a negative refractive power; a third lens element having a positive refractive power and a concave surface facing the object side; and a fourth lens element having a negative refractive power, wherein the following conditional expressions are satisfied, 0.6 <|f 2 /f |<1.8 0≦ f 2 /R 4<1.7 0< f 12 /f 34<0.9 where f denotes a focal length of an entire lens system, f 2 denotes a focal length of the second lens element, R 4 denotes a curvature radius of an object-side surface of the second lens element, f 12 denotes a combined focal length of the first and second lens elements, and f 34 denotes a combined focal length of the third and fourth lens elements.