Patent ID: 7675691

Claim:
A zoom lens system comprising a plurality of lens units, in order from an object side to an image side, including at least: a first lens unit having positive optical power; a second lens unit having negative optical power; and a third lens unit having positive optical power, wherein magnification change is performed by changing an interval between the individual lens units, wherein the first lens unit moves relative to an image surface during changing the magnification from a wide-angle side to a telephoto side, wherein the second lens unit, in order from the object side to the image side, comprises: a lens element A having negative optical power; a lens element B that has an aspheric surface and has negative optical power; and a lens element C having positive optical power, wherein both surfaces of the lens element B have a radius of curvature other than infinity, and wherein the second lens unit satisfies the following conditions (1) and (2): 1.85<NdA<2.20 (1) 1.88<NdC<2.20 (2), where: NdA is the refractive index to the d-line of the lens element A, and NdC is the refractive index to the d-line of the lens element C.