Patent ID: 8264784

Claim:
An optical system, comprising: a first lens having positive refractive power, with both surfaces thereof being convex; a second lens having negative refractive power, with both surfaces thereof being concave; a third lens having positive refractive power and a meniscus shape; and a fourth lens having negative refractive power, with both surfaces thereof being concave, all of which are disposed in order from an object to a front upper surface, wherein the refractive powers of the first lens to the fourth lens satisfy the following Conditional Expressions 1 and 6: f ⁢ ⁢ 1 f ⁢ ⁢ 4 < - 1.1 , and Conditional ⁢ ⁢ Expression ⁢ ⁢ 1 - 1.5 < f ⁢ ⁢ 2 F < - 0.7 Conditional ⁢ ⁢ Expression ⁢ ⁢ 6 and - 1.5 < f ⁢ ⁢ 2 F < - 0.7 , Conditional ⁢ ⁢ Expression ⁢ ⁢ 6 where f1 is the focal distance of the first lens, f is the focal distance of the fourth lens, f2 is the focal distance of the second lens, and F is the entire focal distance of the optical system.