Patent ID: 9448386
Filing Date: 2016-09-20
CPC Classification: G02B

Claim Text:
1. An imaging lens comprising: a first lens group having positive refractive power; a second lens group having negative refractive power; and a third lens group having negative refractive power, arranged in this order from an object side to an image plane side, wherein said first lens group includes a first lens having positive refractive power, a second lens having negative refractive power, and a third lens having positive refractive power, said second lens group includes a fourth lens and a fifth lens, said third lens group includes a sixth lens having positive refractive power and a seventh lens having negative refractive power, said fourth lens is formed in a meniscus shape so that a concave surface thereof faces the object side near an optical axis thereof, 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 sixth lens has an Abbe's number νd6, and said seventh lens has an Abbe's number νd7 so that the following conditional expressions are satisfied: said fourth lens has a focal length f4 so that the following conditional expression is satisfied: where f is a focal length of a whole lens system.