Zoom lens and image pickup apparatus including the same

A zoom lens consisting of, 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 positive refractive power;
• and
• a rear lens group including a plurality of lens units,
• wherein an interval between each pair of adjacent lens units is changed during zooming,
• wherein the first lens unit is configured not to move during zooming,
• wherein the third lens unit is configured to move toward the object side during zooming from a wide angle end to a telephoto end,
• wherein the first lens unit includes three or more positive lenses,
• wherein the following conditional expressions are satisfied:
• 0.18<fw/f1<5.00;
• 8.2<TTD/skw<100.0;
• and
• 0.5<f1 min/f1<50.0,
• where fw represents a focal length of the zoom lens at the wide angle end, f1 represents a focal length of the first lens unit, TTD represents a distance from a lens surface closest to the object side to an image plane, skw represents a back focus at the wide angle end, and flmin represents a focal length of a positive lens having a smallest refractive power among the three or more positive lenses included in the first lens unit.