Patent ID: 8780457

Claim:
An optical photographing system comprising, in order from an object side to an image side: a first lens element with positive refractive power having an object-side surface being convex at a paraxial region thereof; a second lens element with negative refractive power having an object-side surface being concave at a paraxial region thereof; a third lens element having refractive power; a fourth lens element having refractive power; a fifth lens element with positive refractive power having an image-side surface being convex at a paraxial region thereof, wherein an object-side surface and the image-side surface of the fifth lens element are aspheric; and a sixth lens element with refractive power having an mage-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 curvature radius of the object-side surface of the second lens element is R 3 , a curvature radius of an image-side surface of the second lens element is R 4 , and the following relationship is satisfied: −0.70 <R 3 /|R 4|≦0.