Zoom lens, and image pickup apparatus having the same

An image pickup apparatus comprising:

• a zoom lens;
• and
• an image sensor configured to receive image light formed by the zoom lens,
• the zoom lens comprising a plurality of lens units, the plurality of lens units consisting of, in order from an object side to an image side, a first lens unit having negative refractive power, a second lens unit having positive refractive power, a third lens unit having negative refractive power, and a fourth lens unit having positive refractive power,
• wherein a distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end,
• wherein the first lens unit includes three or more lenses,
• wherein the first lens unit is fixed relative to an image plane during zooming, and
• wherein the following inequalities are satisfied:
• 0.85<(−f1)/f2<2.00
• 0.00<(−f1)/f4<0.55
• 0.00<LD1/TTL<0.27
• where f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, f4 is a focal length of the fourth lens unit, LD1 is a distance on an optical axis from a lens surface on the object side of a lens closest to an object in the first lens unit to a lens surface on the image side of a lens closest to the image plane in the first lens unit, and TTL is a distance on the optical axis from the lens surface on the object side of the lens closest to the object in the zoom lens at the wide-angle end to the image plane.