Patent ID: 8780465

Claim:
An optical system, comprising a first lens having positive refractive power and being convex toward an object side; a second lens having negative refractive power and being concave toward an image side; a third lens having positive refractive power and being biconvex; a fourth lens having positive refractive power and being convex toward the image side; a fifth lens having negative refractive power and being convex in the center toward the object side and concave in the center toward the image side, the fifth lens having at least one inflection point on an image-side surface; and an aperture stop disposed in front of the first lens to adjust a light amount, wherein the optical system satisfies the following conditional expression: 1.744≦ r 1≦1.938 1.658≦ r 4≦3.145 where r1 is a radius of curvature of an object-side surface of the first lens and r4 is a radius of curvature of an image-side surface of the second lens, and wherein the first lens, the second lens, the third lens, the fourth lens and the fifth lens are arranged in order from the object side to the image side.