Patent ID: 8508648

Claim:
An imaging lens comprising: a first lens having positive refractive power; a second lens having negative refractive power; a third lens having positive refractive power; and a fourth lens arranged in this order from an object side to an image side, wherein said first lens is formed so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive; said second lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive; said third lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are negative; said fourth lens is formed in a shape so that both a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image side are positive; when the first lens has a focal length of f1 and the second lens has a focal length f2, the imaging lens is configured to satisfy the following conditional expression: 0.3< |f 1 /f 2|<0.7, and when the whole lens system has a focal length f and composite focal length of the second lens and the third lens is f23, the imaging lens is configured to satisfy the following conditional expression: 1.5< f 23 /f< 9.0.