The present invention comprises a first lens group (G1) having a positive refractive power and a rear group (GR) having a plurality of lens groups, the first lens group and the rear group being arranged side by side on the optical axis in order from an object side, wherein: when the magnification is varied from a wide-angle end to a telephoto end, the distance between the first lens group (G1) and the rear group (GR) changes; distances between the plurality of lens groups constituting the rear group (GR) change from each other; the rear group (GR) has, in order from the object side, a first focusing lens group (GF1) having a negative refractive power and a second focusing lens group (GF2) having a negative refractive power; both the first and second focusing lens groups move toward an image side on the optical axis when focusing from infinity to a short distance position; and the following conditional expression is satisfied.

0.000<(MWF1/MTF1)/(MWF2/MTF2)<0.500

where

MWF1, which is an amount of movement of the first focusing lens group when focusing from infinity to a short distance position in the wide-angle end state, MTF1, which is an amount of movement of the first focusing lens group when focusing from infinity to a short distance position in the telephoto end state,

MWF2, which is an amount of movement of the second focusing lens group when focusing from infinity to a short distance position in the wide-angle end state, and

MTF2, which is an amount of movement of the second focusing lens group when focusing from infinity to a short distance position in the telephoto end state, are all set such that the movement toward the image side is positive.

The present invention comprises a first lens group (G1) having a positive refractive power and a rear group (GR) having a plurality of lens groups, the first lens group and the rear group being arranged side by side on the optical axis in order from an object side, wherein: when the magnification is varied from a wide-angle end to a telephoto end, the distance between the first lens group (G1) and the rear group (GR) changes; distances between the plurality of lens groups constituting the rear group (GR) change from each other; the rear group (GR) has, in order from the object side, a first focusing lens group (GF1) having a negative refractive power and a second focusing lens group (GF2) having a negative refractive power; both the first and second focusing lens groups move toward an image side on the optical axis when focusing from infinity to a short distance position; and the following conditional expression is satisfied.

0.000<(MWF1/MTF1)/(MWF2/MTF2)<0.500

where

MWF1, which is an amount of movement of the first focusing lens group when focusing from infinity to a short distance position in the wide-angle end state, MTF1, which is an amount of movement of the first focusing lens group when focusing from infinity to a short distance position in the telephoto end state,

MWF2, which is an amount of movement of the second focusing lens group when focusing from infinity to a short distance position in the wide-angle end state, and

MTF2, which is an amount of movement of the second focusing lens group when focusing from infinity to a short distance position in the telephoto end state, are all set such that the movement toward the image side is positive.

A variable magnification optical system (ZL) comprises a front group (GA) and a rear group (GB). The rear group (GB) has a first focusing lens group (GF1) and a second focusing lens group (GF2). From focusing on an object at infinity to focusing on a short-distance object, the front group (GA) is fixed with respect to an image surface, and the first focusing lens group (GF1) and the second focusing lens group (GF2) move on different trajectories along an optical axis. The variable magnification system satisfies the following conditional expressions.

0.25<βF1t/βF1w<2.00

0.25<βF2w/βF2t<2.00 where βF1t is the magnification of the first focusing lens group (GF1) in a telephoto end state, βF1w is the magnification of the first focusing lens group (GF1) in a wide-angle end state, βF2t is the magnification of the second focusing lens group (GF2) in the telephoto end state, and βF2w is the magnification of the second focusing lens group (GF2) in the wide-angle end state.

A variable magnification optical system (ZL) comprises a front group (GA) and a rear group (GB). The rear group (GB) has a first focusing lens group (GF1) and a second focusing lens group (GF2). From focusing on an object at infinity to focusing on a short-distance object, the front group (GA) is fixed with respect to an image surface, and the first focusing lens group (GF1) and the second focusing lens group (GF2) move on different trajectories along an optical axis. The variable magnification system satisfies the following conditional expressions.

0.25<βF1t/βF1w<2.00

0.25<βF2w/βF2t<2.00 where βF1t is the magnification of the first focusing lens group (GF1) in a telephoto end state, βF1w is the magnification of the first focusing lens group (GF1) in a wide-angle end state, βF2t is the magnification of the second focusing lens group (GF2) in the telephoto end state, and βF2w is the magnification of the second focusing lens group (GF2) in the wide-angle end state.

An imaging optical system includes lens group Gm located on that is closest to an object among lens groups in which a distance between the lens groups changes during zooming, the lens groups having negative power. Lens group Gm includes, in order from the object side toward an image side, lens element LGmF1 having the negative power, lens element LGmF2 having the negative power, both surfaces of lens element LGmF2 having an aspherical shape, and at least two lens elements having power. The present disclosure provides the imaging optical system having good various aberrations such as spherical aberration, astigmatism, and distortion and an imaging device and a camera system that are provided with the imaging optical system.

An imaging optical system includes lens group Gm located on that is closest to an object among lens groups in which a distance between the lens groups changes during zooming, the lens groups having negative power. Lens group Gm includes, in order from the object side toward an image side, lens element LGmF1 having the negative power, lens element LGmF2 having the negative power, both surfaces of lens element LGmF2 having an aspherical shape, and at least two lens elements having power. The present disclosure provides the imaging optical system having good various aberrations such as spherical aberration, astigmatism, and distortion and an imaging device and a camera system that are provided with the imaging optical system.

A variable-power optical system (ZL) is constituted by, in order from the object side and along the optical axis, the following: a first lens group (G1) that has a positive refractive power; a second lens group (G2); a third lens group (G3) that has a negative refractive power; and a rear group (GR) that includes a plurality of lens groups. When power is varied from the wide-angle end to the telephoto end, the interval between the first lens group and the second lens group increases, the interval between the second lens group and the third lens group increases, and the interval between the third lens group and a lens group in the rear group positioned closest to the object decreases, thus satisfying the following conditional equation:

0.10<D1/D2<1.80, where D1 is the length on the optical axis from the lens plane closest to the object of the first lens group to the lens plane closest to the image, and D2 is the length on the optical axis from the lens plane closest to the object of the second lens group to the lens plane closest to the image.

A variable-power optical system (ZL) is constituted by, in order from the object side and along the optical axis, the following: a first lens group (G1) that has a positive refractive power; a second lens group (G2); a third lens group (G3) that has a negative refractive power; and a rear group (GR) that includes a plurality of lens groups. When power is varied from the wide-angle end to the telephoto end, the interval between the first lens group and the second lens group increases, the interval between the second lens group and the third lens group increases, and the interval between the third lens group and a lens group in the rear group positioned closest to the object decreases, thus satisfying the following conditional equation:

0.10<D1/D2<1.80, where D1 is the length on the optical axis from the lens plane closest to the object of the first lens group to the lens plane closest to the image, and D2 is the length on the optical axis from the lens plane closest to the object of the second lens group to the lens plane closest to the image.

Provided is a zoom lens, including, in order from an object side: first positive, second negative, third positive lens units, and rear lens group, in which intervals between the first and second lens units, between the second and third lens units, and between the third lens unit and the rear lens group, are respectively is increased, decreased and changed, in which the zoom lens includes an image stabilization unit A configured to move not in an optical axis direction during image blur correction, and an image stabilization unit B configured to rotate around a point on or near the optical axis during the image stabilization, and in which focal lengths of the image stabilization unit B and the zoom lens, maximum value θt of image blur correction angle, and rotation angle of the image stabilization unit B upon the image blur correction angle θt are appropriately set.

Provided is a zoom lens, including, in order from an object side: first positive, second negative, third positive lens units, and rear lens group, in which intervals between the first and second lens units, between the second and third lens units, and between the third lens unit and the rear lens group, are respectively is increased, decreased and changed, in which the zoom lens includes an image stabilization unit A configured to move not in an optical axis direction during image blur correction, and an image stabilization unit B configured to rotate around a point on or near the optical axis during the image stabilization, and in which focal lengths of the image stabilization unit B and the zoom lens, maximum value θt of image blur correction angle, and rotation angle of the image stabilization unit B upon the image blur correction angle θt are appropriately set.