Patent ID: 8503095

Claim:
A zoom lens system, comprising, in an order from an object side to an image side: a first lens unit having positive refractive power; a second lens unit having negative refractive power; a third lens unit having positive refractive power; a fourth lens unit having negative refractive power; and a fifth lens unit having positive refractive power, wherein: in zooming from a wide angle end to a telephoto end, the first lens unit, the second lens unit, the third lens unit, and the fourth lens unit move so that an interval between the first lens unit and the second lens unit is larger at the telephoto end than that at the wide angle end, an interval between the second lens unit and the third lens unit is smaller at the telephoto end than that at the wide angle end, and an interval between the third lens unit and the fourth lens unit varies; and the following conditional expressions are satisfied: 10.0< f 1/ fw< 23.0; and 0.35< f 1/ ft≦ 0.647, where f1 denotes a focal length of the first lens unit, and fw and ft denote focal lengths of an entire system at the wide angle end and at the telephoto end, respectively.