Patent ID: 7724446

Claim:
A zoom lens system, in order from an object side to an image side along an optical axis, comprising: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; a fourth lens group having positive refractive power; and a fifth lens group having positive refractive power; wherein, during zooming of the zoom lens system from a wide-angle end to a telephoto end for changing a focal length thereof, the second and third lens groups are moved independently toward the object side in such a manner that a spacing between the second and third lens groups increases and a spacing between the first and second lens groups decreases; and wherein the zoom lens system satisfies the following condition: 1.05 ≤ f W · L W f T · Y ≤ 1.53 where f W represents the focal length of the zoom lens system at the wide-angle end, f T represents the focal length of the zoom lens system at the telephoto end, Y represents a maximum diagonal length of an image plane, and L w represents a total length of the zoom lens system at the wide-angle end which is defined as a distance from the vertex of a first surface of the first lens on the object side to the image plane.