Patent ID: 8576496

Claim:
An imaging lens system, in order from an object side to an image side comprising two non-cemented lens elements with refractive power: a positive first lens element having a convex object-side surface at a paraxial region thereof and a convex or flat image-side surface at the paraxial region thereof; and a negative second lens element having a concave object-side surface at a paraxial region thereof and a concave image-side surface at a paraxial region thereof, and both the object-side and image-side surfaces being aspheric; wherein, the shape of the image-side surface of the second lens element changes from concave when near an optical axis to convex when away from the optical axis; wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, a focal length of the imaging lens system is f, half of the maximal field of view is HFOV, and they satisfy the following relations: 0.4<ln( V 1/ V 2)<1.1; −1.0≦( R 1+ R 2)/( R 1− R 2)<0.4; and 1.0 mm< f /tan(HFOV)<7.5 mm.