Patent ID: 8724237

Claim:
An optical photographing 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; second lens element with positive refractive power; a third lens element with negative refractive power; a fourth lens element with refractive power having a convex object-side surface and a concave image-side surface, wherein the object-side surface and the image-side surface of the fourth lens element are aspheric; a fifth lens element with positive refractive power having a convex image-side surface, wherein an object-side surface and the image-side surface of the fifth lens element are aspheric; and a sixth lens element with negative refractive power having a concave image-side surface, wherein the image-side surface of the sixth lens element changes from concave at a paraxial region thereof to convex at a peripheral region thereof, and an object-side surface and the image-side surface of the sixth lens element are aspheric; wherein a focal length of the optical photographing lens system is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, and the following relationships are satisfied: 0 <f 2 /f 1<5.0; and 0<( f/f 1)/(( f/f 2)+( f/f 4))<2.0.