Patent ID: 8861099

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; a fifth lens having negative refractive power; and a sixth 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 surface thereof on the object side has a positive curvature radius, said second lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have positive curvature radii, said third lens is formed in a shape so that a surface thereof on the image plane side has a negative curvature radius, said fourth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have negative curvature radii, said fifth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have negative curvature radii, said sixth lens is formed to have negative refractive power near an optical axis and positive refractive power increasing toward a periphery portion thereof, said sixth lens is formed in a shape so that a surface thereof on the image plane side has an aspheric shape having an inflexion point, 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, said fifth lens has an Abbe's number νd5, and said sixth lens has an Abbe's number νd6 so that the following conditional expressions are satisfied: 45<ν d 1<75 20<ν d 2<40 45<ν d 3<75 45<ν d 4<75 20<ν d 5<40 45<ν d 6<75.