Patent ID: 8184385

Claim:
An optical system for taking image comprising three lens elements with refractive power, from the object side to the image side: a first lens element with positive refractive power having a convex aspheric front surface and a concave aspheric rear surface; a plastic second lens element with negative refractive power having a concave aspheric front surface and a convex aspheric rear surface; a plastic third lens element with negative refractive power having a convex aspheric front surface and a concave aspheric rear surface, and the third lens element being formed with at least one inflection point; and an aperture stop located in front of the first lens element; a center thickness of the second lens element being CT 2 , a focal length of the third lens element being f 3 , a focal length of the optical system being f, a height at the position of the effective diameter of the front surface of the third lens being SAG 31 , they satisfying the relations: CT 2<0.34 mm; | f/f 3|>0.2; SAG 31<0 mm.