The optical system includes a plurality of lens groups in which an interval between adjacent lens groups changes when focusing, and an aperture stop, and when intervals between an exit pupil of an on-axis ray by the aperture stop and an image plane in an infinite-distance object focusing state, a first short-distance object focusing state in which an imaging magnification is β1, and a second short-distance object focusing state in which an imaging magnification is β2 are Pinf, P1, and P2, respectively, the optical system satisfies predetermined conditions. An imaging apparatus includes the optical system and an image sensor.

The optical system includes a plurality of lens groups in which an interval between adjacent lens groups changes when focusing, and an aperture stop, and when intervals between an exit pupil of an on-axis ray by the aperture stop and an image plane in an infinite-distance object focusing state, a first short-distance object focusing state in which an imaging magnification is β1, and a second short-distance object focusing state in which an imaging magnification is β2 are Pinf, P1, and P2, respectively, the optical system satisfies predetermined conditions. An imaging apparatus includes the optical system and an image sensor.

A 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 first lens group and the fifth lens group are not moved, and the second lens group, the third lens group, and the fourth lens group are moved. The second lens group includes a negative lens closest to the object side. In a case where a focal length of the second lens group is denoted by f2 and a focal length of the negative lens of the second lens group closest to the object side is denoted by f21, the zoom lens satisfies 0.6<f2/f21<0.9.

A 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 first lens group and the fifth lens group are not moved, and the second lens group, the third lens group, and the fourth lens group are moved. The second lens group includes a negative lens closest to the object side. In a case where a focal length of the second lens group is denoted by f2 and a focal length of the negative lens of the second lens group closest to the object side is denoted by f21, the zoom lens satisfies 0.6<f2/f21<0.9.

An image capturing lens system includes four lens groups which include eight lens elements. The four lens groups are, in order from an object side to an image side: first, second, third and fourth lens groups. The eight lens elements are, in order from the object side to the image side: first, second, third, fourth, fifth, sixth, seventh and eighth lens elements. The first and second lens elements respectively have positive and negative refractive power. At least one lens element in the second through fourth lens groups has an inflection point. A focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process. The second lens group is moved relative to the first lens group along an optical axis in the zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end.

An image capturing lens system includes four lens groups which include eight lens elements. The four lens groups are, in order from an object side to an image side: first, second, third and fourth lens groups. The eight lens elements are, in order from the object side to the image side: first, second, third, fourth, fifth, sixth, seventh and eighth lens elements. The first and second lens elements respectively have positive and negative refractive power. At least one lens element in the second through fourth lens groups has an inflection point. A focal length of the image capturing lens system is varied by changing axial distances between the four lens groups in a zooming process. The second lens group is moved relative to the first lens group along an optical axis in the zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end.

The zoom lens consists of, in order from an object side, a first lens group having a positive power, a second lens group having a negative power, a third lens group having a positive power, a fourth lens group having a negative power, and a fifth lens group having a positive power. An aperture diaphragm is disposed between a surface of the second lens group closest to an image side and a surface of the fourth lens group closest to the object side. The first lens group and the fifth lens group each consist of two or less lenses. A negative meniscus lens, which is convex toward the object side, is disposed to be closest to the object side of the second lens group. A negative meniscus lens, which is convex toward the image side, is disposed to be closest to the image side of the fourth lens group.

Provided is a zoom lens, including, in order from an object side, a positive first lens unit, a negative second lens unit, a positive third lens unit, a negative fourth lens unit, and a positive fifth lens unit, in which an interval between each pair of adjacent lens units is changed during zooming, in which the second lens unit moves during focusing, and includes, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, and a negative lens, and in which a focal length of the second lens unit, a thickness of the second lens unit on an optical axis, a refractive index of a material of the positive lens included in the second lens unit, and an average value of refractive indices of materials of the negative lenses included in the second lens unit are each appropriately set.

Provided is a zoom lens, including, in order from an object side, a positive first lens unit, a negative second lens unit, a positive third lens unit, a negative fourth lens unit, and a positive fifth lens unit, in which an interval between each pair of adjacent lens units is changed during zooming, in which the second lens unit moves during focusing, and includes, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, and a negative lens, and in which a focal length of the second lens unit, a thickness of the second lens unit on an optical axis, a refractive index of a material of the positive lens included in the second lens unit, and an average value of refractive indices of materials of the negative lenses included in the second lens unit are each appropriately set.

Provided is a zoom lens. The zoom lens includes a fixed lens group having a positive optical power, a first zoom lens group having a negative optical power, a second zoom lens group having a positive optical power, and a compensation lens group having a positive optical power which are sequentially arranged along an optical axis from an object side to an image side, where the first zoom lens group and the second zoom lens group are capable of reciprocating along the optical axis. The fixed lens group includes a first lens, and the first zoom lens group includes a second lens, a third lens, and a fourth lens which are sequentially arranged along the optical axis from the object side to the image side.