Patent ID: 7885014

Claim:
A zoom lens system comprising, in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a negative refractive power; an aperture stop; and a fourth lens unit having a positive refractive power, wherein the fourth lens unit includes, in order from the object side, a front lens subunit having a positive refractive power and a rear lens subunit having a positive refractive power with a largest air interval in the fourth lens unit therebetween, wherein the following expression is satisfied, 0.400<ν m /(ν rp−νrn )<0.630, where νm represents the Abbe number of the material of a first positive lens having the largest dispersion of the positive lenses included in the rear lens subunit, νrp represents the average Abbe number of materials of positive lenses other than the first positive lens in the rear lens subunit, and νrn represents the average Abbe number of materials of negative lenses in the rear lens subunit.