Zoom lens and image pickup apparatus including the same
A zoom lens according to the present invention includes, in order from an object side to an image side, first to third lens units with positive, negative and positive refractive powers, and a rear group including two or more lens units, in which an interval between adjacent lens units is varied during zooming. The zoom lens includes a correction lens unit which has a function of moving an imaging position in a direction perpendicular to an optical axis. The correction lens unit includes, in order from the object side to the image side, a positive first subunit, a positive second subunit which moves in a direction having a component of the direction perpendicular to the optical axis, and a negative third subunit. Focal lengths of the zoom lens when focused at infinity at a wide angle end and the correction lens unit are appropriately set.
1 . A zoom lens including a plurality of lens units, an interval between adjacent lens units of the plurality of lens units being varied during zooming, the plurality of lens units comprising:
a first lens unit with a positive refractive power;
a second lens unit with a negative refractive power;
a third lens unit with a positive refractive power; and
a rear group consisting of three lens units having a lens unit B and a lens unit FA,
the first lens unit, the second lens unit, the third lens unit and the rear group being arranged in order from an object side to an image side,
wherein the first lens unit consists of a negative lens, a positive lens and a positive lens arranged in order from the object side to the image side,
wherein the second lens unit consists of a negative lens, a negative lens, a positive lens and a negative lens arranged in order from the object side to the image side,
wherein the third lens unit includes three positive lenses,
wherein a lens unit arranged closest to the image side in the zoom lens consists of a negative lens and a positive lens arranged in order from the object side to the image side,
wherein at least a subunit included in the plurality of lens units moves in a direction having a component of a direction perpendicular to an optical axis during an image blurring correction,
wherein the lens unit FA moves toward the image side during focusing from an infinity to a closest distance, the lens unit FA being arranged adjacent to the lens unit arranged closest to the image side in the zoom lens and having a negative refractive power,
wherein the lens unit B has a positive refractive power, and consists of a positive lens A, a negative lens B and a positive lens C arranged in order from the object side to the image side, the lens unit B being arranged at the object side of the lens unit FA, and
wherein the following inequality is satisfied:
3.40 ≤fxyz/fw <4.55
where fw is a focal length of the zoom lens when focused at infinity at a wide angle end and fxyz is a focal length of the third lens unit.
2 . The zoom lens according to claim 1 , wherein the positive lens included in the lens unit arranged closest to the image side in the zoom lens has a biconvex shape.
3 . The zoom lens according to claim 2 , wherein the negative lens included in the lens unit arranged closest to the image side in the zoom lens has a meniscus shape which is concave toward the object side.
4 . The zoom lens according to claim 3 , wherein each of the positive lens and the negative lens included in the lens unit arranged closest to the image side in the zoom lens is a single lens.
5 . The zoom lens according to claim 1 , wherein the negative lens B and the positive lens C are cemented with each other.
6 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
3.40 ≤fxyz/fw <4.30.
7 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
1.0 <fxyz/fy <1.43
where fy is a focal length of the subunit.
8 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.8<( Ryz 1+ Ryz 2)/( Ryz 1− Ryz 2)<1.89
where Ryz1 is a curvature radius of a lens surface arranged closest to the image side in the subunit, and Ryz2 is a curvature radius of a lens surface on the object side in a lens which is arranged adjacent to the subunit at the image side.
9 . An image pickup apparatus comprising:
a zoom lens including a plurality of lens units, an interval between adjacent lens units of the plurality of lens units being varied during zooming; and
an image pickup element receiving light of an image formed by the zoom lens,
the plurality of lens units including:
a first lens unit with a positive refractive power;
a second lens unit with a negative refractive power;
a third lens unit with a positive refractive power; and
a rear group consisting of three lens units having a lens unit B and a lens unit FA,
the first lens unit, the second lens unit, the third lens unit and the rear group being arranged in order from an object side to an image side,
wherein the first lens unit consists of a negative lens, a positive lens and a positive lens arranged in order from the object side to the image side,
wherein the second lens unit consists of a negative lens, a negative lens, a positive lens and a negative lens arranged in order from the object side to the image side,
wherein the third lens unit includes three positive lenses,
wherein a lens unit arranged closest to the image side in the zoom lens consists of a negative lens and a positive lens arranged in order from the object side to the image side,
wherein at least a subunit included in the plurality of lens units moves in a direction having a component of a direction perpendicular to an optical axis during an image blurring correction,
wherein the lens unit FA moves toward the image side during focusing from an infinity to a closest distance, the lens unit FA being arranged adjacent to the lens unit arranged closest to the image side in the zoom lens and having a negative refractive power,
wherein the lens unit B has a positive refractive power, and consists of a positive lens A, a negative lens B and a positive lens C arranged in order from the object side to the image side, the lens unit B being arranged at the object side of the lens unit FA, and
wherein the following inequality is satisfied:
3.40 ≤fxyz/fw <4.55
where fw is a focal length of the zoom lens when focused at infinity at a wide angle end and fxyz is a focal length of the third lens unit.
10 . The image pickup apparatus according to claim 9 , wherein the positive lens included in the lens unit arranged closest to the image side in the zoom lens has a biconvex shape.
11 . The image pickup apparatus according to claim 10 , wherein the negative lens included in the lens unit arranged closest to the image side in the zoom lens has a meniscus shape which is concave toward the object side.
12 . The image pickup apparatus according to claim 11 , wherein each of the positive lens and the negative lens included in the lens unit arranged closest to the image side in the zoom lens is a single lens.