Zoom lens system

A zoom lens system comprising 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, at least said first, second and third lens groups are moved so that the distance between said first lens group and said second lens group increases, the distance between said second lens group and said third lens group decreases, and the distance between said third lens group and said fourth lens group increases;
• wherein said lens system satisfies the following conditions:
• 0.10<fw/f1<0.300.25<fw/f4<0.450.60<X3/(ft−fw)<0.85
• wherein
• fw designates the focal length of the entire zoom lens system at the short focal length extremity;
• ft designates the focal length of the entire zoom lens system at the long focal length extremity;
• fi designates the focal length of the ith lens group (i=1 to 4);
• and
• X3 designates the traveling distance of said third lens group from the short focal length extremity to the long focal length extremity.