Patent ID: 7580202

Claim:
A zoom lens system, in order from an object side to an image side, comprising: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; and a subsequent lens-unit set including at least one lens unit, wherein intervals between the first lens unit, the second lens unit, and the lens units included in the subsequent lens-unit set change during zooming, wherein the first lens unit includes a negative lens element, an optical element, and a positive lens element, and wherein the following conditional expressions are satisfied, 0.755<θ gF −(−1.665×10 −7 ·νn 3 +5.213×10 −5 ·νn 2 −5.656×10 −3 ·νn )<1.011 0.023<| f 1 /( f 1n ·ν 1n )|<0.050 3.2<β 3it /β 3iw <6.0 where νn and θgF denote an Abbe number and a partial dispersion ratio, respectively, of a material composing the optical element; f 1n and ν 1n denote a focal length of the negative lens element and an Abbe number of a material composing the negative lens element, respectively; f 1 denotes a focal length of the first lens unit; and β 3iw and β 3it denote lateral magnifications of the subsequent lens-unit set at a wide-angle end and at a telephoto end, respectively.