Patent ID: 8514500

Claim:
An imaging lens system, in order from an object side to an image side comprising five lens elements with refractive power: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a plastic third lens element having at least one of the object-side and image-side surfaces thereof being aspheric; a plastic fourth lens element having a concave image-side surface, at least one of the object-side and image-side surfaces thereof being aspheric; and a plastic fifth lens element with positive refractive power having a convex object-side surface and a convex image-side surface, and at least one of the object-side and image-side surfaces thereof being aspheric; wherein a focal length of the imaging lens system is f, a focal length of the third lens element is f3, an axial distance between the object-side surface of the first lens element and an image plane is TTL, a maximal image height of the imaging lens system is ImgH, a back focal length of the imaging lens system is BFL, and they satisfy the following relations: | f/f 3|<1.1; TTL/ImgH< 2.0; and 0 <BFL/TTL< 0.40.