Imaging lens
AssigneeKantatsu Co., Ltd.
InventorsYoji Kubota, Kenichi Kubota, Hitoshi Hirano, Hisao Fukaya
Life of this patent
Estimating the term…
Abstract
An imaging lens includes a first lens having positive refractive power; a second lens having positive refractive power; a third lens; a fourth lens; a fifth lens; and a sixth lens having negative refractive power, arranged in this order from an object side to an image plane side. The sixth 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 negative. The surface of the sixth lens on the image plane side has the specific curvature radius so that a specific conditional expression is satisfied.
Claims14
An imaging lens comprising:
- a first lens having positive refractive power;
- a second lens having positive refractive power;
- a third lens;
- a fourth lens;
- a fifth lens;
- and
- a sixth lens having negative refractive power, arranged in this order from an object side to an image plane side with spaces in between each of the lenses,
- wherein said imaging lens has a total of six lenses,
- said sixth 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 negative, and
- said sixth lens has the surface on the image plane side having the curvature radius R6r, said second lens has Abbe's number νd2, said fourth lens has Abbe's number νd4, and said sixth lens has Abbe's number νd6 so that the following conditional expressions are satisfied:
- −10<R6r/f<−1,
- 35<νd2<75,
- 15<νd4<35,
- 35<νd6<75,
- where f is a focal length of a whole lens system.
Dependencies are inferred from the claim text.