US Patent 7274519 Zoom lens system

Providing a compact zoom lens system having a high zoom ratio. The zoom lens system includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. When a state of lens group positions varies from a wide-angle end state W to a telephoto end state T, at least the first lens group G1 and the third lens group G3 are moved along the optical axis to the object. Given conditional expressions are satisfied.