A variable magnification optical system consists of, in order from an object side to an image side, a first lens group, a second lens group, and a subsequent lens group. The variable magnification optical system satisfies a predetermined conditional expression for a partial dispersion ratio related to F line, C line, and a wavelength of 1970.09 nm, a d-line back focus of the variable magnification optical system at a telephoto end, a back focus in any one wavelength from a wavelength of 1300 nm to a wavelength of 2325.42 nm at the telephoto end, and a d-line focal length of the variable magnification optical system at the telephoto end.

A zoom lens consists of, 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, a third lens unit having a positive refractive power, and a rear unit that includes a plurality of lens units. All lens units move during zooming, and a distance between adjacent lens units changes. The third lens unit includes, in order from the object side to the image side, a first subunit having a positive refractive power, a second subunit having a positive refractive power, and a third subunit having a positive refractive power. The second subunit includes a negative lens and a positive lens. The second subunit moves in a direction having a component orthogonal to an optical axis during an image stabilization. A predetermined condition is satisfied.

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; upon varying magnification, the first lens group being fixed with respect to the image plane and each distance between the neighboring lens groups being varied; the rear lens group comprising a focusing lens group which is moved upon carrying out focusing; and the predetermined conditional expressions being satisfied, whereby it is possible to suppress superbly variations in aberrations upon varying the magnification.

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, a third lens unit having a positive refractive power, and a fourth lens unit having a negative refractive power. In the zoom lens, an interval between each pair of adjacent lens units is changed during zooming, and the first lens unit is configured not to move for zooming. Further, a total length DT of the zoom lens at a telephoto end, a focal length fT of the zoom lens at the telephoto end, a distance BW of a back focus at a wide-angle end, a total length DW of the zoom lens at the wide-angle end, and a focal length f3 of the third lens unit are each appropriately set.

Provided is a variable magnification optical system comprising, in order from an object side along an optical axis, 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; upon zooming from a wide angle end state to a telephoto end state, 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 and the fourth lens group being varied; the third lens group G3 comprising, in order from the object side along the optical axis, a 3a-th lens group G3a having positive refractive power, an aperture S, and a 3b-th lens group G3b having positive refractive power; a lens group having negative refractive power within the 3b-th lens group G3b being used as a vibration reduction lens group and moved so as to include a component in a direction orthogonal to the optical axis, whereby image plane correction is performed when image blurring occurs; and predetermined conditions being satisfied. Whereby, a small-size and high-performance variable magnification optical system, capable of realizing a small variation in aberration and attaining a sufficient brightness even in the telephoto state, an imaging apparatus, and a method for manufacturing the variable magnification optical system are provided.

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 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 being moved; and a predetermined conditional expression being satisfied. With such 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.

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 consists of, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a stop, and a negative fourth lens group. During zooming, the second and third lens groups move. The fourth lens group consists of, in order from the object side, a fourth A lens group, a negative fourth B lens group moving during image blur correction, a positive fourth C lens group, and a negative fourth D lens group moving during focusing, and a positive fourth E lens group. The zoom lens satisfies predetermined conditional expressions.

An objective optical system consists of, in order from an object side, a first lens group having a negative refractive power, which is stationary all the time, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power, which is stationary all the time. At a time of focusing from an object point at a long distance to an object point at a short distance, the second lens group moves toward the object side and the third lens group moves toward an image side. The following conditional expressions (1), (5), and (7) are satisfied:

2<fG2/f<8(1)

0.2<(t34ft34n)/f<0.5(5)

8<fG1/f<2(7).