Patent ID: 7978420

Claim:
A zoom lens comprising: a first lens group having negative refracting power; a second lens group having positive refracting power; and a third lens group having positive refracting power, disposed in the order from an object side to an image side, wherein, during zooming from a wide angle end to a telephoto end, the first lens group is moved and the second lens group is moved together with a stop toward the object such that an air space between the first lens group and the second lens group decreases and such that an air space between the second lens group and the third lens group increases, the second lens group includes a positive lens aspherically shaped on at least a side thereof facing the object and having a convex surface facing the object and a negative lens positioned on the image side of the positive lens, aspherically shaped on at least a side thereof facing the image and having a concave surface facing the image, and the zoom lens is configured to satisfy the following Conditional Expressions (1) and (2) 0.7 <R 2 f/R 2 r< 2.0 (1) 1.0 <|Sga/Sgs|< 1.5 (2) wherein R 2 f represents a paraxial radius of curvature of the object-facing surface of the positive lens; R 2 r represents a paraxial radius of curvature of the image-facing surface of the negative lens; Sgs represents the sag of the paraxial radius of curvature of the image-facing surface in the effective aperture of the image-facing surface of the negative lens; and Sga represents the sag of the aspherical shape of the image-facing surface in the effective aperture of the image-facing surface of the negative lens.