Patent ID: 7920334

Claim:
A zoom lens system comprising, in order from an object along an optical axis: a first lens group having negative refractive power; a second lens group having positive refractive power; and a third lens group having positive refractive power; for zooming from a wide-angle end state to a telephoto end state, each distance between adjacent lens groups is variable , and the following conditional expression being satisfied: 0.45816<( Nnav− 0.80)× ft ×tan ω w/TLw < 0.90 where Nnav denotes an average of refractive indices at d-line (wave length λ=587.6 nm) of all negative lenses included in the zoom lens system, ft denotes a focal length of the zoom lens system in the telephoto end state, ωw denotes a half angle of view of the zoom lens system in the wide-angle end state, and TLw denotes a total lens length of the zoom lens system in the wide-angle end state.