Patent ID: 7443613

Claim:
A three-piece lens assembly comprising: a first lens group being a positive meniscus lens with a convex surface facing the object side and with another surface facing an aperture; a second lens group being a positive meniscus lens with a concave surface facing the aperture and the object side; a third lens group being a biconcave lens with a concave surface facing the second lens and the object side and with another surface facing the image side, the concave surface of the third lens facing the object side being greater than the another surface of the third lens facing the image side in radius of curvature; wherein both sides of the first, second and third lens groups are aspheric and are all made of plastic material; a focal length of the first lens group is f 1 , and a focal length of the second lens group is f 2 , they satisfy the relation: 5.0<f 2 /f 1 <18.0.