Zoom lens and image pickup apparatus including the same

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

• a first lens unit having a positive refractive power that does not move for zooming;
• a second lens unit having a negative refractive power that moves during zooming;
• a third lens unit having a positive refractive power that moves during zooming;
• a fourth lens unit having a positive refractive power that moves during zooming;
• and a fifth lens unit, in which an interval between each pair of all of the first lens unit, the second lens unit, the third lens unit, the fourth lens unit, and the fifth lens unit is changed during zooming, wherein
• the third lens unit moves during zooming along a locus having a zoom position at which a distance between a surface closest to the image side of the first lens unit and a surface closest to the object side of the third lens unit on an optical axis is longer than that at a wide angle end, and
• the zoom lens satisfies the following conditions:
• 1.0<Lw/Lt<10.0,
• 1.0<Dw/Dt<100.0, and
• −5.0<f1/f2<−0.5,
• where Lw and Lt respectively represent distances between the surface closest to the image side of the first lens unit and a surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and a telephoto end, Dw and Dt respectively represent distances between a surface closest to the image side of the third lens unit and the surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and the telephoto end, and f1 and f2 respectively represent focal lengths of the first lens unit and the second lens unit.

An image pickup apparatus comprising:

• a zoom lens;
• and
• an image pickup element that receives light of an image formed by the zoom lens,
• the 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;
• a third lens unit having a positive refractive power;
• a fourth lens unit having a positive refractive power;
• and a rear lens unit including at least one lens unit, wherein
• the second lens unit includes one or more lens sub-units, and has a negative refractive power as a whole,
• the first lens unit does not move for zooming, the second lens unit moves during zooming, the fourth lens unit moves during zooming,
• the zoom lens includes a stop between the second lens unit and the third lens unit or between the third lens unit and the fourth lens unit, and
• the zoom lens satisfies the following expressions:
• 0.50<(ft×β2w2)/(fw×β2t2)<1.40 and
• −2.45<f1/f2<−0.50,
• where β2w and β2t respectively represent lateral magnifications of the second lens unit at a wide angle end and a telephoto end when a light beam enters from infinity, fw and ft respectively represent focal lengths of the zoom lens at the wide angle end and the telephoto end, f1 represents a focal length of the first lens unit, and f2 represents a focal length of the second lens unit at the wide angle end.

An image pickup apparatus comprising:

• a zoom lens;
• and
• an image pickup element that receives light of an image formed by the zoom lens,
• the zoom lens comprising in order from an object side to an image side:
• a first lens unit having a positive refractive power that does not move for zooming;
• a second lens unit having a negative refractive power that moves during zooming;
• a third lens unit having a positive refractive power that moves during zooming;
• a fourth lens unit having a positive refractive power that moves during zooming;
• and a fifth lens unit, in which an interval between each pair of all of the first lens unit, the second lens unit, the third lens unit, the fourth lens unit, and the fifth lens unit is changed during zooming, wherein
• the third lens unit moves during zooming along a locus having a zoom position at which a distance between a surface closest to the image side of the first lens unit and a surface closest to the object side of the third lens unit on an optical axis is longer than that at a wide angle end, and
• the zoom lens satisfies the following conditions:
• 1.0<Lw/Lt<10.0,
• 1.0<Dw/Dt<100.0, and
• −5.0<f1/f2<−0.5,
• where Lw and Lt respectively represent distances between the surface closest to the image side of the first lens unit and a surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and a telephoto end, Dw and Dt respectively represent distances between a surface closest to the image side of the third lens unit and the surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and the telephoto end, and f1 and f2 respectively represent focal lengths of the first lens unit and the second lens unit.