Patent ID: 8780460

Claim:
An imaging lens system comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface at a paraxial region; a second lens element having positive refractive power; a third lens element having positive refractive power; a fourth lens element having refractive power; and a fifth lens element with refractive power having a concave image-side surface at a paraxial region, wherein the image-side surface of the fifth lens element changes from concave at the paraxial region to convex at a peripheral region, and both of an object-side surface and the image-side surface of the fifth lens element are aspheric; wherein a focal length of the imaging lens system is f, a curvature radius of an object-side surface of the second lens element is R3, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, and the following relationships are satisfied: −0.80 <f/R 3<4.0; −1.5 <f/f 4<0.45; and 0 <|f 5/ f 4|<1.50.