Zoom lens and image pickup apparatus including the same

A zoom lens comprising:

• a first lens unit having positive refractive power;
• a second lens unit having negative refractive power;
• a third lens unit having positive or negative refractive power;
• and
• a rear lens group including one or more lens units,
• wherein the first lens unit, the second lens unit, the third lens unit and the rear lens group are arranged in order from an object side to an image side along an optical axis of the zoom lens,
• wherein, during zooming from a wide-angle end to a telephoto end, the second lens unit moves along the optical axis so that a distance between the first lens unit and the second lens unit increases,
• wherein an aperture stop is provided on the image side of the second lens unit, and
• wherein, when a sum of relative anomalous partial dispersion ΔθgF of materials of negative lenses included in the second lens unit is indicated by SUM(ΔθgF2N), a sum of optical power of negative lenses formed of a material having relative anomalous partial dispersion ΔθgF that is equal to or more than an average value of relative anomalous partial dispersion ΔθgF of the materials of the negative lenses included in the second lens unit is indicated by φ2SUM, and an optical power of the second lens unit is indicated by φ2, the following conditions are satisfied:
• 0.065<SUM(ΔθgF2N)<0.200
• 0.4<φ2SUM/φ2<2.0.