Patent ID: 7301711

Claim:
A fast zoom lens system comprises a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth 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, a distance between said negative second lens group and said positive third lens group decreases, and a distance between said positive third lens group and said positive fourth lens group decreases; wherein said fast zoom lens system satisfies the following conditions: 6.0 <f 1 /fw< 10.0 3.0 <f 3 /fw <8.0 wherein f 1 designates the focal length of said positive first lens group; f 3 designates the focal length of said positive third lens group; and fw designates the focal length of the entire fast zoom lens system at the short focal length extremity; wherein said positive fourth lens group comprises three positive lens elements, and wherein at least one of said three positive lens elements is bonded to a negative lens element.