In an optical system according to each exemplary embodiment, an interval between adjacent lens units changes in focusing from an infinite-distance object to a close-distance object, and a first in-focus state in which ?=?1.2 is obtained can be caused, where ? is a lateral magnification of an entire system. The optical system according to each exemplary embodiment includes a plurality of focus lens units, and out of a focus lens unit having a largest absolute value of a focus sensitivity and a focus lens unit having a second largest absolute value of a focus sensitivity in a state in which focus is put on an infinite-distance object, a focus lens unit disposed on an object side is a lens unit LA, and a focus lens unit disposed on an image side is a lens unit LB. A partial optical system LC including all lenses disposed on the image side of the lens unit LB has negative refractive power. The partial optical system LC satisfies a predetermined conditional expression.

A zoom lens ZL includes: a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and a third lens unit L3 having a positive refractive power, an N?1th lens unit, and an Nth lens unit, the lens units being arranged in order from an object side to an image side. The N?1th lens unit and the Nth lens unit are located on the image side with respect to an aperture stop SP.

A zoom lens system according to the disclosure, in order from an object side to an image side, includes a first lens group with positive optical power, a second lens group with negative optical power, and a subsequent lens group composed of at least three lens groups. During zooming operation, the first lens group moves along the optical axis and the second lens group does not move. The second lens group has an aperture stop. The second lens group satisfies following condition (1),

9.0fG1/fG22.0 (1) where fG1 is the focal length of the first lens group, and fG2 is the focal length of the second lens group.

The present invention provides a zoom lens which is the zoom lens that includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power in order from an object side, and changes focal length by changing an air interval between the respective lens groups, the zoom lens including a focus group F constituted from one lens in or after the third lens group G3, moving only the focus group F along an optical axis direction when focusing from an infinity object to a proximity object, and satisfying specific conditional expressions, and an imaging apparatus including the zoom lens.

A zoom optical system (ZL) comprises, in order from an object: a first lens group (G1) having a positive refractive power; a second lens group (G2) having a negative refractive power; a third lens group (G3) having a positive refractive power; and a subsequent lens group (GR), wherein upon zooming, a distance between the first lens group (G1) and the second lens group (G2) changes, a distance between the second lens group (G2) and the third lens group (G3) changes, and a distance between the third lens group (G3) and the subsequent lens group (GR) changes, the subsequent lens group (GR) comprises a focusing lens group that moves upon focusing, and the second lens group (G2) comprises a partial group that satisfies following conditional expressions, 1.40<fvr/f2<2.30, 1.80<f1/fw<3.50 where fvr: a focal length of the partial group, f2: a focal length of the second lens group (G2), f1: a focal length of the first lens group (G1), and fw: a focal length of the zoom optical system (ZL) in a wide-angle end state.

A variable magnification optical system comprising a plurality of lens groups which includes a first negative lens group having negative refractive power, a second negative lens group disposed at a more image side than the first negative lens group and having negative refractive power, a third negative lens group disposed at a more image side than the second negative lens group and having negative refractive power; upon varying a magnification, distances between adjacent lens groups being varied; the first negative lens group being movable to include a component in a direction perpendicular to the optical axis as a vibration reduction lens group; the second negative lens group being moved along the optical axis upon carrying out focusing; and the predetermined conditional expression(s) being satisfied. The variable magnification optical system can attain a high optical performance and be made in small in size.

A zoom lens includes, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a negative fifth lens group, and magnifies by changing an interval on an optical axis between adjacent lens groups. The third lens group includes an object side portion group arranged on an object side with a widest air interval in the third lens group and an image side portion group arranged on an image side of the object side portion group, and the second lens group moves along the optical axis at a time of magnification change. The object side portion group and the image side portion group each include a positive lens, a positive lens, and a negative lens arranged in order from the object side. Further, an imaging device including the zoom lens is provided.

A lens system, from an object side to an image side in the following order, includes; an object-side lens group that is disposed closest to the object side and having positive refractive power; a focusing lens group that moves during a focusing operation and having negative refractive power; a third lens group; a wobbling lens group that vibrates in an optical axis direction; and an image-side lens group that is disposed closest to the image side.

In an optical system according to each exemplary embodiment, an interval between adjacent lens units changes in focusing from an infinite-distance object to a close-distance object, and a first in-focus state in which =1.2 is obtained can be caused, where is a lateral magnification of an entire system. The optical system according to each exemplary embodiment includes a plurality of focus lens units, and out of a focus lens unit having a largest absolute value of a focus sensitivity and a focus lens unit having a second largest absolute value of a focus sensitivity in a state in which focus is put on an infinite-distance object, a focus lens unit disposed on an object side is a lens unit LA, and a focus lens unit disposed on an image side is a lens unit LB. A partial optical system LC including all lenses disposed on the image side of the lens unit LB has negative refractive power. The partial optical system LC satisfies a predetermined conditional expression.

Provided are: a zoom lens including, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, an Intermediate group having one or more lens groups and having positive refractive power as a whole, a lens group having negative refractive power, and a rear group having one or more lens groups, wherein the intermediate group includes at least two lens surfaces each of which is a cemented surface and is a diverging surface, a space between adjacent lens groups changes in zooming, the lens group moves on an optical axis in focusing, and the zoom lens satisfies the predetermined conditional expression; and an imaging apparatus including the zoom lens.