Zoom lens and image pickup apparatus having the same

An image pickup apparatus comprising:

• a zoom lens 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 positive refractive power, a fourth lens unit having a positive refractive power, and a fifth lens unit having a negative refractive power, wherein
• the first lens unit does not move for zooming,
• each of the distances between the lens units adjacent to each other is changed during zooming, and
• when a magnification amount Z2 of the second lens unit, a magnification amount Z3 of the third lens unit, and a magnification amount Z4 of the fourth lens unit are given by
• Z2=β2t/β2w,
• Z3=β3t/β3w, and
• Z4=β4t/β4w,
• where β2w and β2t are respectively lateral magnifications of the second lens unit focused at infinity at a wide angle end and a telephoto end, β3w and β3t are respectively lateral magnifications of the third lens unit focused at infinity at the wide angle end and the telephoto end, and β4w and β4t are respectively lateral magnifications of the fourth lens unit focused at infinity at the wide angle end and the telephoto end, the following conditional expressions are satisfied:
• 2.0<Z2/(Z3×Z4)<5.0, and
• 0.5<|f5|/M5<2.0
• where f5 is a focal length of the fifth lens unit, and M5 is an amount of movement of the fifth lens unit in zooming from the wide angle end to the telephoto end while focused at infinity;
• and
• a solid-state image pickup element that receives an image formed by the zoom lens.