Patent ID: 7982971

Claim:
A zoom lens system comprising, in order of from an object side to an image side: a first lens unit having a positive refractive power, which does not move for zooming; a second lens unit having a negative refractive power, which moves during zooming; a third lens unit having a negative refractive power, which moves during zooming; and a fourth lens unit having a positive refractive power, which does not move for zooming, wherein: the first lens unit includes a negative lens, a positive lens, a positive lens, and a positive lens arranged in this order from the object side to the image side, and when an Abbe number ν and a partial dispersion ratio θ of a material of the negative lens in the first lens unit are denoted respectively by νn and θn, an average value of Abbe numbers ν and an average value of partial dispersion ratios θ of materials of the positive lenses in the first lens unit are denoted respectively by νpa and θpa, and a refractive power of the negative lens in the first lens unit is denoted by φn, conditions expressed by the following expressions are satisfied: −1.75×10 −3 <(θ pa−θn )/(ν pa−νn ); and 9.1×10 −3 (1/mm)<|φ n|.