US Patent 7817351 Zoom lens system

A zoom lens system includes, in order from the object side, a negative first lens group, a positive second lens group; and a positive third lens group. The first lens group includes, in order from the object side to the image side, a negative first lens and a positive second lens. The second lens group includes, in order from the object side to the image side, a positive third lens, a negative fourth lens, and a negative fifth lens. The zoom lens system satisfies certain conditions related to the configuration of the lens and lens groups of the zoom lens system in order to provide a compact zoom lens having excellent correction of aberrations.