Patent ID: 7813051

Claim:
A high zoom-ratio zoom lens system of five lens groups comprises a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group, in this order from an object, wherein upon zooming from the short focal length extremity to the long focal length extremity, a distance between said positive first lens group and said negative second lens group increases, and a distance between said negative second lens group and said positive third lens group decreases; and wherein said high zoom-ratio zoom lens system satisfies the following conditions: 5.5< f 1/| f 2|<10.0( f 2<0) 1.7< f 3/ f 4<4.0 wherein f 1 designates the focal length of said positive first lens group; f 2 designates the focal length of said negative second lens group; f 3 designates the focal length of said positive third lens group; f 4 designates the focal length of said positive fourth lens group.