The imaging lens consists of a positive first lens group remaining stationary during focusing, a negative second lens group, a positive third lens group, and a negative fourth lens group remaining stationary during focusing, in order from an object side. During focusing from the infinite object to the closest object, the second lens group moves to an image side, the third lens group moves to the object side, and the fourth lens group consists of a fourth-a lens group which is a vibration-proof lens group and a fourth-b lens group, in order from the object side. In the imaging lens, predetermined conditional expressions are satisfied.

A zoom lens of the present invention is a zoom lens including a variable stop whose aperture diameter is variable in zooming, the variable stop is a stop which determines a minimum f-number of the zoom lens at least at one of zoom positions in an entire zoom range, and the aperture diameter of the variable stop is variable in focusing at least at a telephoto end in the entire zoom range.

A zoom optical system comprises, in order from an object: a front lens group (GFS) having a positive refractive power; an M1 lens group (GM1) having a negative refractive power; an M2 lens group (GM2) having a positive refractive power; and an RN lens group (GRN) having a negative refractive power, wherein upon zooming, distances between the front lens group and the M1 lens group, between the M1 lens group and the M2 lens group, and between the M2 lens group and the RN lens group change, upon focusing from an infinite distant object to a short distant object, the RN lens group moves, and the M2 lens group comprises an A lens group that satisfies a following conditional expression, 1.10<fvr/fTM2<2.00, where, fvr: a focal length of the A lens group, and fTM2: a focal length of the M2 lens group in a telephoto end state.

A zoom lens includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a rear lens group including a lens unit having negative refractive power arranged along an optical axis thereof. A focal length fw of the zoom lens at a wide-angle end, a focal length ft of the zoom lens at a telephoto end, an amount of movement M1 of the first lens unit on the optical axis in zooming from the wide-angle end to the telephoto end, and a focal length frn of a lens unit Lrn that is a lens unit having a shortest focal length among lens units having negative refractive power included in the rear lens group are appropriately set based on predetermined mathematical conditions.

In a zoom lens including a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power that are arranged in order from an object side to an image side, a movement locus of each of the lens units, an amount of movement of the third lens unit when zooming from a wide angle end to a telephoto end, and a focal length of the third lens unit are set as appropriate.

A zoom lens includes positive first, negative second, positive third units, and rear group. An interval between first and second units is larger and that between second and third units is smaller at telephoto end (TE) than at wide angle end. Second unit or a negative sub-unit corresponding to a part of second unit serves as first image stabilizing (IS) unit moving during image blur correction in a direction having a component in a direction perpendicular to optical axis. A negative sub-unit corresponding to a part of third unit or a negative unit included in rear group serves as second IS unit. A distance from a surface closest to object side of first IS unit to image plane at TE, a distance from a surface closest to object side of second IS unit to image plane at TE, and focal length of the zoom lens at TE are appropriately set.

In a zoom lens system, a distance between a first lens group and a second lens group is increased, a distance between the second lens group and a third lens group is reduced, and a distance between the third lens group and a fourth lens group is reduced. The third lens group includes, in order from an object side, a front lens group and a rear lens group separated from each other by a widest air gap on an optical axis in the third lens group. Camera-shake correction is performed by moving whole or part of the front lens group as a camera-shake correction lens group perpendicularly to the optical axis. Conditional formula below is satisfied: 3.0<fis/f3<0.9, where f3 represents a focal length of the third lens group and fis represents a focal length of the camera-shake correction lens group.

Composing, in order from an object side along the optical axis, a first lens group having positive refractive power, and at least one lens group; upon varying magnification, an interval between the first lens group and a lens group at an image side of the first lens group and adjacent thereto being varied, said first lens group comprising a focusing lens group which is moved along the optical axis for focusing and a vibration reducing lens group that is movable to include a component in a direction perpendicular to the optical axis, thereby providing a an excellent optical performance upon focusing.

A variable magnification optical system comprising, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear lens group having negative refractive power; upon varying a magnification from a wide angle end state to a tele photo end state, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the rear lens group being varied; the third lens group or the rear lens group comprising a focusing lens group which is moved upon carrying out focusing from an infinitely distant object to a closely distant object; and predetermined conditional expression(s) being satisfied, thereby various aberrations being corrected superbly.

A zoom lens includes, in order from object side to image side, a first lens unit having positive refractive power; a second lens unit having negative refractive power; a third lens unit having positive refractive power; and a rear lens group including one or more lens units. During zooming, three or more lens units move to change an interval between adjacent lens units. The third lens unit includes, in order from object side to image side, a first lens subunit having positive refractive power, a second lens subunit having negative refractive power, and a third lens subunit having positive refractive power. The second lens subunit moves in a direction having a component perpendicular to the optical axis regarding image blurring correction, a focal length of the zoom lens at the telephoto end and a focal length of the third lens unit are set to satisfy specific mathematical conditions.