A zoom optical system includes a positive first lens group, a negative second lens group disposed on an image side of the first lens group, a positive third lens group disposed on an image side of the second lens group, a negative fourth lens group disposed on an image side of the third lens group, and a final lens group disposed on an image side of the fourth lens group and closest to an image. During zooming, distances between lens groups change, and the first lens group moves along an optical axis. A negative focusing lens group is provided, and the final lens group is disposed on an image side of the focusing lens group. A negative vibration proof group of the second lens group may include, in order from an object, a negative lens, an air gap and a cemented lens of a negative lens and a positive lens. The final lens group may have negative refractive power.

A zoom lens system includes a positive first lens group, a negative second lens group, a positive intermediate lens group, and a negative image-side lens group. Upon zooming from the short to long focal length extremities, a distance between the first and second lens groups increases, and a distance between the second and intermediate lens groups decreases. The image-side lens group consists of two lens elements. The following conditions are satisfied:
6.0<f1/f2<4.3,
5.4<f1/fIMG<3.9, and
0.3<D2/fw<3.0, f1, f2 and fIMG designate the focal lengths of the first, second and the image-side lens groups, respectively, D2 designates a distance between the second lens group and the intermediate lens group, at the short focal length extremity, fw designates the focal length of the zoom lens system at the short focal length extremity.

Provided is a zoom lens having, in order from an object, a first lens group (G1) having positive refractive power, a second lens group (G2) having negative refractive power, a third lens group (G3) having positive refractive power, and a fourth lens group (G4) having positive refractive power. Upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, a distance between the third lens group and the fourth lens group changes, and at least the first lens group (G1) moves. The first lens group (G1) is constituted by a set of cemented lenses, the third lens group (G3) is constituted by, in order from the object, a positive lens and a negative lens, and the conditional expression 0.50<TL/ft<1.28 is satisfied, where TL denotes a total length of the zoom lens (ZL) in the telephoto end state, and ft denotes a focal length of the zoom lens (ZL) in the telephoto end state.

According to an embodiment of the present disclosure, an image capturing optical system includes a first lens group having a positive refractive power and disposed along an optical axis and to face an object. A second lens group has a negative refractive power and disposed along the optical axis and adjacent to the first lens group, and second lens group includes a focus correction lens to correct a difference in a focused position according to a variation in a position of the object. A third lens group has a positive refractive power and disposed along the optical axis. A subsequent lens group adjacent the third lens group and disposed along the optical axis and to face an image of the object, and the lens group subsequent to the second lens group includes a camera shake correction lens to move in a direction perpendicular to the optical axis.

Provided is a zoom lens including, 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; and a third lens unit having a positive refractive power, in which an interval between each pair of adjacent lens units is changed during zooming, the first lens unit consists of, in order from the object side to the image side, a positive lens and a negative lens, and a focal length of the first lens unit, a focal length of the third lens unit, a focal length of the negative lens, and a focal length of an entire system of the zoom lens at a wide-angle end are each appropriately set.

A variable magnification optical system comprises, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power and a fourth lens group G4 having negative refractive power; upon varying a magnification, a distance between the first lens group G1 and the second lens group G2 being varied, a distance between the second lens group G2 and the third lens group G3 being varied, and a distance between the third lens group G3 and the fourth lens group G4 being varied; upon focusing, the fourth lens group G4 being moved; and a predetermined conditional expression being satisfied. With such a configuration, there is provided a variable magnification optical system whose focusing lens group is compact in size and reduced in weight, so high speed and quiet focusing can be effected without lens barrel being made large in size, and further by which variations in aberrations upon varying magnification from the wide angle end state to the telephoto end state as well as variations in aberrations upon focusing from the infinite distance object to the close distance object can be superbly suppressed.

The zoom lens includes, in order from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, a diaphragm, and a fourth lens group G4. During zooming, only the second lens group G2 and the third lens group G3 move. The first lens group G1 includes, in order from the object side, a cemented lens that is formed by cementing a positive lens and a negative meniscus lens convex toward the object side, a positive lens, and a negative lens. A conditional expression (1): 0.8<f1a/f1b<0 is satisfied, where f1a is a composite focal length of the first to third lenses from the object side of the first lens group G1, and f1b is a focal length of the fourth lens.

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 a first lens unit with positive refractive power, a second lens unit with negative refractive power, an intermediate group including an aperture stop and at least one lens unit, and a rear group including at least two lens units placed in this order from an object side to an image side, and an interval between adjacent lens units changes during zooming. The lens unit of the rear group placed closest to the object side has the strongest negative refractive power among lens units placed closer to the image side than the aperture stop. In zooming from a wide-angle end to a telephoto end, every lens unit of the first lens unit, the intermediate group, and the rear group moves toward the object side, and the second lens unit moves along a convex trajectory toward the image side. The zoom lens satisfies predetermined inequalities.

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.