Zoom lens and image pickup apparatus

An image pickup apparatus comprising:

• a zoom lens;
• and
• an image pickup element configured to pick up an image formed by the zoom lens,
• wherein the zoom lens comprising, in order from an object side to an image side:
• a first lens unit having a positive refractive power and configured not to move for zooming;
• two or more intermediate lens units configured to move in zooming;
• and
• a rear lens unit having a positive refractive power,
• wherein an interval between each pair of adjacent lens units changes in zooming,
• wherein the first lens unit includes, in order from the object side to the image side, a first lens subunit having a negative refractive power and configured not to move for focusing, a second lens subunit having a positive refractive power and configured to move for focusing, and a third lens subunit having a positive refractive power, and
• wherein the zoom lens satisfies following inequalities:
• 1.655≤(f1+bok1)/f1≤3.000, and
• 2.370≤ft/f1≤3.145, and
• 43.0°≤ωw≤50.0°,
• where f1 denotes a focal length of the first lens unit, bok1 denotes a length on an optical axis from a last surface of the first lens unit to a rear principal point of the first lens unit, and ft denotes a focal length of the zoom lens at a telephoto end, and ωw denotes a half angle of view of the zoom lens at a wide-angle end and is defined by a following equation:
• ωw=arctan(Y/fw),
• where 2Y denotes a diagonal image size of the image pickup apparatus, fw denotes a focal length of the zoom lens at the wide-angle end.

A zoom lens comprising, in order from an object side to an image side:

• a first lens unit having a positive refractive power and configured not to move for zooming;
• two or more intermediate lens units configured to move in zooming;
• and
• a rear lens unit having a positive refractive power,
• wherein an interval between each pair of adjacent lens units changes in zooming,
• wherein the first lens unit includes, in order from the object side to the image side, a first lens subunit having a negative refractive power configured not to move for focusing, a second lens subunit having a positive refractive power and configured to move for focusing, and a third lens subunit having a positive refractive power, and
• wherein the zoom lens satisfies following inequalities:
• 1.655≤(f1+bok1)/f1≤3.000,
• 1.810≤ft/f1≤6.300, and
• 15.0≤ft/fw≤35.0,
• where f1 denotes a focal length of the first lens unit, bok1 denotes a length on an optical axis from a last surface of the first lens unit to a rear principal point of the first lens unit, ft denotes a focal length of the zoom lens at a telephoto end, and fw denotes a focal length of the zoom lens at a wide-angle end.