High-magnification zoom lens system

A high-magnification zoom lens system comprising a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth 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 positive first lens group, said positive third lens group, said negative fourth lens group, and said positive fifth lens group move from the image side toward the object side;
• wherein said high-magnification zoom lens system satisfies the following conditions:
• 0.65<(fw*ft)½f1<0.95−7.0<(fw*ft)½/f2<−4.80.80<X4/X5<0.95
• wherein
• fw designates the focal length of the entire high-magnification zoom lens system at the short focal length extremity;
• ft designates the focal length of the entire high-magnification zoom lens system at the long focal length extremity;
• f1 designates the focal length of said positive first lens group;
• f2 designates the focal length of said negative second lens group;
• X4 designates the traveling distance of said negative fourth lens group upon zooming from the short focal length extremity to the long focal length extremity;
• and
• X5 designates the traveling distance of said positive fifth lens group upon zooming from the short focal length extremity to the long focal length extremity.