Zoom lens and image pickup apparatus including the same

An image pickup apparatus, comprising:

• a zoom lens, comprising, in order from an object side to an image side:
• a first lens group which is not moved for zooming and is composed of a single lens unit having a positive refractive power;
• a second lens group which has a negative refractive power and comprises at least one lens unit each of which is moved toward an image side during zooming from a wide angle end to a telephoto end;
• a third lens group which has a positive refractive power and comprises at least one lens unit each of which is moved toward the object side during zooming from the wide angle end to the telephoto end;
• a fourth lens group which is configured to move during zooming and focusing and is composed of a single lens unit having a negative refractive power;
• and
• a rear lens group which is composed of at least one lens unit,
• wherein intervals between adjacent lens units are changed during zooming,
• wherein the first lens group comprises at least three lenses, and
• wherein the following conditional expressions are satisfied:
• 4.80<f1/fw<8.00;
• −5.00<M2/Mv<−1.50;
• −3.50<Mv/fw<−0.77;
• and
• 0.99<Nd1pr/Nd1pf<1.40,
• where f1 represents a focal length of the first lens group, fw represents a focal length of the zoom lens at the wide angle end, M2 represents an amount of movement of a lens unit which is moved by a largest amount during zooming from the wide angle end to the telephoto end among the at least one lens unit included in the second lens group, Mv represents an amount of movement of a lens unit which is moved by a largest amount during zooming from the wide angle end to the telephoto end among lens units which are moved toward an object side during zooming from the wide angle end to the telephoto end, Nd1pr represents a refractive index with respect to a d-line of a material of a positive lens G1pr arranged closest to the image side in the first lens group, Nd1pf represents an average of refractive indices with respect to the d-line of materials of positive lenses included in the first lens group other than the positive lens G1pr, and a sign of an amount of movement of a lens unit is defined as positive when the lens unit is located closer to the image side at the telephoto end than at the wide angle end;
• and
• an image pickup element configured to receive light of an image formed by the zoom lens.