Patent ID: 8842377

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 positive refractive power; and a fifth lens having negative refractive power in this order from an object side to an image side, wherein 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 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 negative, said first lens and said second lens have a composite focal length f12, and said third lens and said fourth lens have a composite focal length f34 so that the following conditional expression is satisfied: 1.592 ≦f 34 /f 12<4.0, and said first lens has an Abbe's number νd1, said second lens has an Abbe's number νd2, said third lens has an Abbe's number νd3, said fourth lens has an Abbe's number νd4, and said fifth lens has an Abbe's number νd5 so that the following conditional expressions are satisfied: 50 <νd 1<85 ν d 2<30 50 <νd 3<85 50 <νd 4<85 50 <νd 5<85.