Zoom lens and image pickup apparatus including the same

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<(θp−θna)/(νp−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.