Patent ID: 7227696

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; and a third lens unit having a positive refractive power, wherein an interval between the first lens unit and the second lens unit at a telephoto end is smaller than an interval between the first lens unit and the second lens unit at a wide-angle end, wherein an interval between the second lens unit and the third lens unit at the telephoto end is larger than an interval between the second lens unit and the third lens unit at the wide-angle end, wherein the first lens unit includes, in order from the object side to the image side, one negative lens whose surface on the image side has a concave shape and one positive lens whose surface on the object side has a convex shape, wherein at least one surface of the negative lens has an aspheric shape, and wherein a refractive index of a material of the negative lens (N 11 ), a thickness of a center portion of the negative lens (DC), a distance from a surface vertex on a lens surface of the negative lens on the object side to an optical effective diameter thereof along an optical axis (SG 1 ), a distance from a surface vertex on a lens surface of the negative lens on the image side to an optical effective diameter thereof along the optical axis (SG 2 ), a focal length of the first lens unit (f 1 ), and a focal length of the zoom lens at the telephoto end (ft) satisfy following conditions: 1.84<N11<2.00 2.2<( DC−SG 1 +SG 2)/ DC< 3.2 0.5 <|f 11 /ft< 0.8.