Patent ID: 8614854

Claim:
A zoom lens comprising: a first lens unit disposed closest to an object of all lens units within the zoom lens and having a positive optical power; and at least one subsequent lens unit being disposed closer to an image than the first lens unit, wherein the first lens unit is moved toward the object during variation of magnification from a wide-angle end to a telephoto end, and wherein the first lens unit comprises at least three lenses including a negative lens disposed closest to the image among the at least three lenses and having an image side concave surface, and a positive lens disposed on an object side next to the negative lens and having an object side convex surface, and satisfies the following conditions: 0.50< Rpo/f 1<2.00; and 1.55< Nn 1<1.68, where Rpo represents a curvature radius of the object side convex surface of the positive lens, f 1 represents a focal length of the first lens unit, and Nn represents a refractive index of a material forming the negative lens.