Patent ID: 7253965

Claim:
A zoom lens system comprising, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having positive refractive power, wherein when a state of lens group positions varies from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group increases, a distance between the second lens group and the third lens group decreases, and a distance between the third lens group and the fourth lens group varies, the third lens group consists of, in order from the object, a front lens group having positive refractive power and a rear lens group having negative refractive power, and only the rear lens group is capable of shifting in a direction substantially perpendicular to an optical axis to correct an image blur caused by a camera shake, and wherein the following conditional expression is satisfied: 3.5 <f 1 /fw <8.0 where f 1 denotes the focal length of the first lens group and fw denotes the focal length of the zoom lens system in the wide-angle end state.