Zoom lens, image pickup apparatus, and image pickup system
A zoom lens includes a plurality of lens units, which consist of, in order from an object side to an image side, a first lens unit having positive refractive power, an intermediate group including a plurality of lens units, and a rear lens unit. A distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end. The first lens unit is fixed relative to an image plane for zooming from the wide-angle end to the telephoto end. The first lens unit consists of a plurality of subunits in which a distance between adjacent subunits changes during focusing, and the plurality of subunits include, in order from the object side to the image side, a first subunit that does not move for focusing, a second subunit having positive refractive power that moves for focusing, and a third subunit having negative refractive power. A predetermined inequality is satisfied.
1 . A zoom lens comprising a plurality of lens units, the plurality of lens units consisting of, in order from an object side to an image side, a first lens unit having positive refractive power, an intermediate group including a plurality of lens units, and a rear lens unit,
wherein a distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end,
wherein the first lens unit is fixed relative to an image plane for zooming from the wide-angle end to the telephoto end,
wherein the first lens unit consists of a plurality of subunits in which a distance between adjacent subunits changes during focusing, and the plurality of subunits include, in order from the object side to the image side, a first subunit that does not move for focusing, a second subunit having positive refractive power that moves for focusing, and a third subunit having negative refractive power, and
wherein the following inequalities are satisfied:
0
.
1
0
<
(
f
1
+
Ok
1
)
/
f
1
<
0.8
1.
<
f
1
/
f
1
b
<
2
.
0
0
where f1 is a focal length of the first lens unit in an in-focus state at infinity, Ok1 is a distance on an optical axis from a lens surface closest to an object of the first lens unit to an image-side principal point of the first lens unit in the in-focus state at infinity, and f1b is a focal length of the second subunit.
2 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0
.
0
0
<
❘
"\[LeftBracketingBar]"
f
1
/
f
1
a
|
<
0
.
3
0
where f1a is a focal length of the first subunit.
3 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
-
1.
<
f
1
/
f
1
c
<
-
0.1
where f1c is a focal length of the third subunit.
4 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.4
<
L
11
/
f
1
<
0.9
where L11 is a distance on the optical axis from the lens surface closest to the object of the first lens unit to a lens surface closest to the image plane of the first lens unit in the in-focus state at infinity.
5 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.2
<
L
1
a
/
f
1
<
0.7
where L1a is a distance on the optical axis from a lens surface closest to the object of the first subunit to a lens surface closest to the image side of the first subunit.
6 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0
.
0
1
<
L
1
ab
/
f
1
<
0.2
where L1ab is a distance on the optical axis from a lens surface closest to the image side of the first subunit to a lens surface closest to the object side of the second subunit in the in-focus state at infinity.
7 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
-
1
2
.
0
<
f
1
/
f
2
<
-
2.
where f2 is a focal length of a second lens unit located closest to the object in the intermediate group.
8 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
2
0
.
0
<
v
1
ap
-
v
1
an
<
4
0
.
0
where v1ap is an average value of Abbe numbers based on d-line of all positive lens materials included in the first subunit, and v1an is an average value of Abbe numbers based on the d-line of all negative lens materials included in the first subunit.
9 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
1.
<
f
1
/
f
1
bc
<
2
.
0
where f1bc is a combined focal length of the second subunit and the third subunit in the in-focus state at infinity.
10 . The zoom lens according to claim 1 , wherein the first lens unit consists of, in order from the object side to the image side, the first subunit, the second subunit, and the third subunit.
11 . The zoom lens according to claim 10 , wherein the third subunit does not move for focusing.
12 . The zoom lens according to claim 10 , wherein the third subunit moves for focusing.
13 . The zoom lens according to claim 1 , wherein each of the plurality of lens units in the intermediate group is movable.
14 . An image pickup apparatus comprising:
a zoom lens; and
an image sensor configured to capture an image formed by the zoom lens,
wherein the zoom lens includes a plurality of lens units, the plurality of lens units consisting of, in order from an object side to an image side, a first lens unit having positive refractive power, an intermediate group including a plurality of lens units, and a rear lens unit,
wherein a distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end,
wherein the first lens unit is fixed relative to an image plane for zooming from the wide-angle end to the telephoto end,
wherein the first lens unit consists of a plurality of subunits in which a distance between adjacent subunits changes during focusing, and the plurality of subunits include, in order from the object side to the image side, a first subunit that does not move for focusing, a second subunit having positive refractive power that moves for focusing, and a third subunit having negative refractive power, and
wherein the following inequalities are satisfied:
0
.
1
0
<
(
f
1
+
Ok
1
)
/
f
1
<
0.8
1.
<
f
1
/
f
1
b
<
2
.
0
0
where f1 is a focal length of the first lens unit in an in-focus state at infinity, Ok1 is a distance on an optical axis from a lens surface closest to an object of the first lens unit to an image-side principal point of the first lens unit in the in-focus state at infinity, and f1b is a focal length of the second subunit.
15 . An image pickup system comprising:
a zoom lens; and
a control unit configured to control the zoom lens during zooming,
wherein the zoom lens includes a plurality of lens unit, the plurality of lens units consisting of, in order from an object side to an image side, a first lens unit having positive refractive power, an intermediate group including a plurality of lens units, and a rear lens unit,
wherein a distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end,
wherein the first lens unit is fixed relative to an image plane for zooming from the wide-angle end to the telephoto end,
wherein the first lens unit consists of a plurality of subunits in which a distance between adjacent subunits changes during focusing, and the plurality of subunits include, in order from the object side to the image side, a first subunit that does not move for focusing, a second subunit having positive refractive power that moves for focusing, and a third subunit having negative refractive power, and
wherein the following inequalities are satisfied:
0
.
1
0
<
(
f
1
+
Ok
1
)
/
f
1
<
0.8
1.
<
f
1
/
f
1
b
<
2
.
0
0
where f1 is a focal length of the first lens unit in an in-focus state at infinity, Ok1 is a distance on an optical axis from a lens surface closest to an object of the first lens unit to an image-side principal point of the first lens unit in the in-focus state at infinity, and f1b is a focal length of the second subunit.
16 . The image pickup system according to claim 15 , wherein the control unit is configured separately from the zoom lens, and includes a transmission unit configured to transmit a control signal for controlling the zoom lens.
17 . The image pickup system according to claim 15 , wherein the control unit is configured separately from the zoom lens, and includes an operation unit configured to operate the zoom lens.
18 . The image pickup system according to claim 15 , further comprising a display unit configured to display information about zoom of the zoom lens.