A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a plurality of lens units which move in zooming, and a final lens unit having a positive refractive power, an interval between each pair of adjacent lens units changing in zooming, the plurality of lens units including a lens unit having a negative refractive power, the first lens unit including a negative lens and a positive lens, at least a part of the first lens unit moving for focusing, the first lens unit including a negative lens made of a material satisfying inequalities defined by a refractive index, an Abbe number, and a partial dispersion ratio, and the zoom lens satifying an inequality defined by a maximum value of an Abbe number of at least one positive lens of the first lens unit.

A zoom lens includes, in order from an object side to an image side, a lens unit closest to the object side and having a positive refractive power, an intermediate unit including at least three lens units and an aperture stop, and a lens unit closest to the image side and having a positive refractive power. A distance between each pair of adjacent lens units changes in zooming. The lens unit closest to the object side is configured not to move for zooming, and the at least three lens units and the aperture stop are configured to move in zooming. The lens unit closest to the image side includes a first positive lens. A predetermined condition is satisfied.

The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a positive fifth lens group. During zooming, the second lens group, the third lens group, and the fourth lens group move. The first lens group consists of, in order from an object side, a negative first a lens group, a positive first b lens group that moves during focusing, and a positive first c lens group. The second lens group includes one positive lens and one or more negative lenses successively in order from a most object side to an image side.

A zoom lens consists of, in order from the object side to the image side, a first lens unit having a positive refractive power and configured not to be moved for zooming, a second lens unit having a negative refractive power and configured to be moved for zooming, and a rear lens group including at least one lens unit. The first lens unit includes at least six lenses, a lens closest to the object side included in the first lens unit is a negative lens, and the zoom lens satisfies conditional expressions: −1.65<f1n/f1<−1.10; 37<ν1n<48; and 87<νpave<100, where f1n is a focal length of the negative lens, ν1n is an Abbe number of the negative lens with respect to d-line, f1 is a focal length of the first lens unit, and νpave is an average of Abbe numbers of positive lenses included in the first lens unit with respect to d-line.

A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, one or two intermediate lens units having positive refractive powers, and a final lens unit having a positive power. A distance between each pair of adjacent lens units changes in zooming from a wide-angle end to a telephoto end. The one or two intermediate lens units include three or four lenses. The one or two intermediate lens units include a single lens having a positive refractive power and being closest to the image side. The final lens unit includes three or four lenses. The zoom lens satisfies specified conditional expressions.

A zoom lens includes, in order from an object side, a first lens group that is positive, a second lens group that is negative, a third lens group that is positive, and a fourth lens group that is positive. During zooming from a wide angle end to a telephoto end, at least the first lens group and the third lens group are fixed and an interval on an optical axis of an adjacent lens group relative thereto is changed. In the zoom lens, the fourth lens group includes at least one positive lens and satisfies a predetermined conditional expression. In addition, an imaging device includes the zoom lens and an image sensor.

A zoom optical system comprises, in order from an object side: a first lens group having positive refractive power; a front-side lens group; an intermediate lens group having positive refractive power; and a rear-side lens group. The front-side lens group is composed of one or more lens groups and has a negative lens group. At least part of the intermediate lens group is a focusing lens group. The rear-side lens group is composed of one or more lens groups. Upon zooming, distances between the first lens group and the front-side lens group, between the front-side lens group and the intermediate lens group, and between the intermediate lens group and the rear-side lens group change. At least one of the following conditional expressions is satisfied:

0.010<fF/fXR<10.000

2.250<TLW/ZD1<10.000

where fF denotes a focal length of the focusing lens group, fXR denotes a focal length of a lens group closet to the image surface in the front-side lens group, TLW denotes an entire length of the optical system in a wide angle end state, and ZD1 denotes a movement amount of the first lens group upon zooming from the wide angle end state to a telephoto end state.

An extender lens changes a focal length of an entire lens system after replacement to a longer focal length side than a focal length of a master lens by replacing a part of the master lens with the extender lens. The extender lens consists of, in order from an object side to an image side, a first lens group, and a negative second lens group. The first lens group is a lens group that has a positive refractive power as a whole and has a shortest focal length among lens groups consisting of one lens component or a plurality of consecutively arranged lens components. The extender lens satisfies a predetermined conditional expression.

A zoom lens consists of 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; three or four moving lens units configured to move in zooming: an aperture stop: and one or two rear lens units including a rear lens unit closest to the object side and configured not to move for zooming. An interval between each pair of adjacent lens units is changed in zooming. The three or four moving lens units include a moving lens unit having a negative refractive power. The three or four moving lens units include a rear positive lens unit closest to the image side and having a positive refractive power. The first lens unit includes three positive lenses. Conditional expressions are satisfied by the zoom lens.

Provided is a zoom lens including, in order from an object side to an image side: a positive first lens unit; a negative second lens unit; a positive third lens unit; a positive fourth lens unit; and a rear unit including at least one lens unit. An interval between each pair of adjacent lens units is changed during zooming. The first lens unit includes, in order from the object side to the image side, a negative lens and a positive lens. A focal length f1 of the first lens unit, a focal length f2 of the second lens unit, a focal length f3 of the third lens unit, and an average value Nd1ave of refractive indices at a d-line of respective materials of the negative lens and the positive lens of the first lens unit are each appropriately set.