There is provided a zoom lens including first and second lens groups independently movable in an optical axis direction in an optical system. Before and after switching between two modes different in minimum focusing distance, a lens group to rule focusing changes between the first and second lens groups or a relative position between the first and second lens groups changes.

A zoom lens includes, in order from an object side to an image side, a first lens unit that has a positive refractive power and does not move for zooming, a second lens unit that has a negative refractive power and moves in zooming, at least two lens units that move in zooming, and a final lens unit that has a positive refractive power, is disposed closest to the image side, and does not move for zooming. The first lens unit includes, in order from the object side to the image side, a first sub-lens unit that has a negative refractive power and does not move for focusing, a second sub-lens unit that has a negative refractive power and moves for focusing, and a third sub-lens unit having a positive refractive power. A distance between the second sub-lens unit and the third sub-lens unit changes for focusing. Predetermined inequalities are satisfied.

A zoom lens includes, in order from an object side to an image side, a first lens unit that has a positive refractive power and does not move for zooming, a second lens unit that has a negative refractive power and moves in zooming, at least two lens units that move in zooming, and a final lens unit that has a positive refractive power, is disposed closest to the image side, and does not move for zooming. The first lens unit includes, in order from the object side to the image side, a first sub-lens unit that has a negative refractive power and does not move for focusing, a second sub-lens unit that has a negative refractive power and moves for focusing, and a third sub-lens unit having a positive refractive power. A distance between the second sub-lens unit and the third sub-lens unit changes for focusing. Predetermined inequalities are satisfied.

A zoom lens system includes: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a positive refractive power; a fifth lens group having a positive refractive power; and a sixth lens group having a positive refractive power, wherein the first to sixth lens groups are sequentially arranged along an optical axis from an object side to an image plane side, and zooming is performed by moving at least one of the second lens group, the fourth lens group and the fifth lens group along the optical axis. A distance between a focal point of light having a first wavelength and a focal point of light having a second wavelength is about 50 μm or less at a wide-angle position and a telephoto position. The first wavelength corresponds to green light, the second wavelength corresponds to near infrared (NIR) light.

A zoom lens consists of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power in this order from an object side. The third lens group includes a cemented lens closest to the object side and a cemented lens closest to an image side, and the fourth lens group consists of a negative lens and a positive lens in this order from the object side. Distances between the lens groups change, and the fifth lens group is fixed, and at least the first lens group and the fourth lens group move when magnification is changed from the wide angle end to the telephoto end.

A zoom lens consists of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power in this order from an object side. The third lens group includes a cemented lens closest to the object side and a cemented lens closest to an image side, and the fourth lens group consists of a negative lens and a positive lens in this order from the object side. Distances between the lens groups change, and the fifth lens group is fixed, and at least the first lens group and the fourth lens group move when magnification is changed from the wide angle end to the telephoto end.

Provided is an optical system, which retains enhanced optical performance at any object distance, and has compact and light-weight focus lens units. Provided is an optical system including a plurality of lens units, in which an interval between adjacent lens units changes during focusing, the optical system including: a positive lens unit arranged closest to an object side; first and second focus lens units having negative refractive powers configured to move during focusing; and an intermediate lens unit having a positive refractive power and arranged between the first and second focus lens units. The first and second focus lens units are configured to move toward an image side during focusing.

A zoom image pickup apparatus includes a mount portion, a zoom lens which forms an image of light incident from the mount portion, and an image pickup element which is disposed at an image forming position. The zoom lens includes a plurality of lens unit, and a focusing lens unit, and the following conditional expressions (1) and (2) are satisfied:

1.5<f.sub.Lt/f.sub.Lw   (1), and

|(y.sub.w7d′−y.sub.w7d)/y.sub.w7d×100<0.66   (2).

Provided is an optical system, comprising, in order from an object side: a positive first unit; a negative second unit; and a positive third unit, in which, during focusing from infinity to a close distance, the second unit moves toward the image side, and an interval between adjacent units is changed, in which the first unit consists of, in order from the object side: a negative first sub-unit, which does not move for image stabilization; a positive second sub-unit, which moves during the image stabilization; and a third sub-unit, which does not moves for the image stabilization, and in which a distance from a lens surface closest to the object side in the first unit to an image plane when focusing at infinity, and a distance from a lens surface closest to the object side in the second sub-unit to the image plane when focusing at infinity are appropriately set.

A variable magnification optical system according to the present invention includes a C lens group having positive refractive power, a B lens group having negative refractive power, and an A lens group having positive refractive power in order from an image side and includes an N lens group having negative refractive power on an object side in relation to the A lens group, wherein when zooming from a wide angle end to a telephoto end, at least the A lens group, the B lens group, and the N lens group are moved relative to an image plane and a predetermined conditional expression is satisfied.