Patent ID: 8259400

Claim:
A zoom lens system comprising, in order from an object side: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power; upon zooming from a wide-angle end state to a telephoto end state, each distance between adjacent lens groups varying, at least one portion of the third lens group shifting in a direction including a component perpendicular to an optical axis, and the following conditional expressions being satisfied: 0.60 <|f 1|/( fw×ft ) 1/2 <0.78 1.20 <f 2/(− f 1)<1.80 where f1 denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, fw denotes a focal length of the zoom lens system in the wide-angle end state, and ft denotes a focal length of the zoom lens system in the telephoto end state.