IMAGING LENS

摘要

An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens; and a fifth lens having negative refractive power, arranged in this order from an object side to an image plane side. The first lens is formed in a shape so that an object side surface thereof has a positive curvature radius. The second lens is formed in a shape so that an object side surface thereof and an image plane side surface thereof have positive curvature radii. The first lens, the third lens, and the second lens have specific Abbe's numbers. The third lens has a specific focal length so that a specific conditional expression is satisfied. The second lens, the third lens, and the fourth lens are arranged so that a specific conditional expression is satisfied.

主权项

1. An imaging lens comprising:
a first lens having positive refractive power; a second lens; a third lens; a fourth lens; 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, each of said first lens and said third lens has an Abbe's number greater than 45, said second lens has an Abbe's number less than 35, said third lens has a focal length f3 so that the following conditional expression is satisfied:
5.58≦|f3|/f≦16.23where f is a focal length of a whole lens system,
said second lens and said third lens are arranged so that the surface of the second lens on the image plane side is situated away from a surface of the third lens on the object side by a distance dA on an optical axis, and said third lens and said fourth lens are arranged so that a surface of the third lens on the image plane side is situated away from a surface of the fourth lens on the object side by a distance dB on the optical axis so that the following conditional expression is satisfied:
0.3