Patent ID: 8300320

Claim:
A zoom lens, comprising, in order from an object side: a first lens unit which has positive refractive power and does not move for magnification-varying; and a second lens unit which has negative refractive power and moves for the magnification-varying, wherein the first lens unit comprises, in order from the object side: a first lens sub unit which has negative refractive power and does not move; a second lens sub unit which has positive refractive power and moves for focusing; and a third lens sub unit which has positive refractive power and does not move; and wherein the following expression is satisfied, −2.27×10 −3 <(θ p−θna )/(ν p−νna )<−1.9×10 −3 , where νna and θna represent an average value of an Abbe number ν and an average value of a partial dispersion ratio θ at a g-line and an F-line of negative lenses included in the first lens sub unit, respectively, νp and θp represent an Abbe number and a partial dispersion ratio of a positive lens having a smallest Abbe number among lenses constituting the first lens sub unit, respectively, θ=(Ng−NF)/(NF−NC), and Ng, NF and NC denote refractive indexes at the g-line, the F-line and a C-line, respectively.