Patent ID: 8830358

Claim:
A high zoom-ratio 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 that order from the object side, wherein upon zooming from the short focal length extremity to the long focal length extremity, at least the first through third lens groups move along the optical axis direction in a manner 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 the amount of movement of said first lens group during zooming is larger than that of said third lens group, wherein said first lens group includes a negative lens element, a positive lens element, and a positive lens element, in that order from the object side, wherein the absolute value of the radius of curvature of the surface on the image side of the negative lens element which is provided within said first lens group is smaller than the absolute value of the radius of curvature of the surface on the object side of the positive lens element which is provided on the object side within said first lens group, and wherein the following condition (1) is satisfied: 1.95 <n 11 (1), wherein n11 designates the refractive index at the d-line of the negative lens element which is provided within said first lens group.