Patent ID: 7561342

Claim:
A zoom lens system comprising, in order from an object along an optical axis: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having positive refractive power; and a fourth lens group having positive refractive power, the first lens group and the fourth lens group being always fixed in the direction of the optical axis upon zooming from a wide-angle end state to a telephoto end state and focusing, the second lens group and the third lens group being moved upon zooming from the wide-angle end state to the telephoto end state, respectively, the second lens group and the third lens group being moved upon focusing from infinity to a close object, respectively, such that the second lens group and the third lens group are moved along the optical axis in the wide-angle end state and the telephoto end state, a moving direction of the second lens group and the third lens group upon focusing in the wide-angle end state is opposite to that in the telephoto end state, and, upon focusing, the second lens group and the third lens group are moved along the optical axis in opposite directions to each other in focal length states other than the wide-angle end state or telephoto end state; wherein the second lens group comprises, in order from the object, a first lens component having positive refractive power, and a second lens component having negative refractive power, and the following conditional expression is satisfied: 0.1< f 21/(− f 22)<1.0 where f 21 denotes the focal length of the first lens component, and f 22 denotes the focal length of the second lens component.