Patent ID: 8879167

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; a fourth lens having negative refractive power; and a fifth lens having negative refractive power, arranged in this order from an object side to an image plane side, wherein said first lens is formed in a shape so that a curvature radius of a surface thereof on the object side is positive, said second lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both positive, said third lens is formed in a shape so that a curvature radius of a surface thereof on the object side is positive, said fifth lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both positive, each of said first lens, said third lens, said fourth lens, and said fifth lens has an Abbe's number greater than 45, said second lens has an Abbe's number less than 35, and said third lens and said fourth lens have a composite focal length f 34 and a whole lens system has a focal length f so that the following conditional expression is satisfied: 5.0 <f 34 /f< 25.0.