Zoom lens and image pickup apparatus
A zoom lens includes, in order from an object side to an image side, a first lens unit that has a positive refractive power and does not move for zooming, a second lens unit that has a negative refractive power and moves in zooming, at least two lens units that move in zooming, and a final lens unit that has a positive refractive power, is disposed closest to the image side, and does not move for zooming. The first lens unit includes, in order from the object side to the image side, a first sub-lens unit that has a negative refractive power and does not move for focusing, a second sub-lens unit that has a negative refractive power and moves for focusing, and a third sub-lens unit having a positive refractive power. A distance between the second sub-lens unit and the third sub-lens unit changes for focusing.
1 . A zoom lens comprising in order from an object side to an image side:
a first lens unit that has a positive refractive power and does not move for zooming;
a second lens unit that has a negative refractive power and moves in zooming;
a middle group that has at least two lens units that move in zooming; and
a final lens unit that has a positive refractive power, is disposed closest to the image side, and does not move for zooming,
wherein the zoom lens further comprises an aperture stop that is disposed between a surface closest to the image side of the second lens unit and a surface closest to the object side of the final lens unit, and moves in zooming,
wherein each distance between adjacent lens groups changes in zooming,
wherein the first lens unit includes, in order from the object side to the image side,
a first sub-lens unit that has a negative refractive power and does not move for focusing;
a second sub-lens unit that has a negative refractive power and moves for focusing; and
a third sub-lens unit having a positive refractive power,
wherein a distance between the second sub-lens unit and the third sub-lens unit changes for focusing,
wherein the second sub-lens unit includes a negative lens, and
wherein following inequalities are satisfied:
0.2
≤
flb
/
fla
≤
3
.
2
35
≤
vlbn
≤
100
0.3
≤
❘
"\[LeftBracketingBar]"
f
2
/
fl
❘
"\[RightBracketingBar]"
≤
0.8
0.08
≤
(
Lspt
-
Lspw
)
/
Skw
≤
0
.80
where f1a is a focal length of the first sub-lens unit, f1b is a focal length of the second sub-lens unit, νbn is an Abbe number with respect to d-line of the negative lens in the second sub-lens unit, f1 is a focal length of the first lens unit, and f2 is a focal length of the second lens unit, Lspw is a distance on an optical axis from a surface closest to the object side of the first lens unit to the aperture stop at a wide-angle end, Lspt is a distance on the optical axis from the surface closest to the object side of the first lens unit to the aperture stop at a telephoto end, and Skw is a distance on the optical axis from a surface closest to the image side of the final lens unit to an image plane.
2 . The zoom lens according to claim 1 , wherein a following inequality is satisfied:
0.1≤| f 1 c/f 1 a|≤ 0.9
where f1c is a focal length of the third sub-lens unit.
3 . The zoom lens according to claim 1 , wherein the first sub-lens unit includes a negative lens, and
wherein a following equality is satisfied:
45≤ν1 an≤ 70
where ν1an is an Abbe number with respect to d-line of the negative lens in the first sub-lens unit.
4 . The zoom lens according to claim 1 , wherein a following inequality is satisfied:
0.2≤| f 1/ f 1 a|≤ 0.8.
5 . The zoom lens according to claim 1 , wherein a following inequality is satisfied:
0.2≤β1 b≤ 0.8
where β1b is a lateral magnification of the second sub-lens unit in an in-focus state at infinity.
6 . The zoom lens according to claim 1 , wherein a following inequality is satisfied:
−2.0≤β1 c≤ 0
where β1c is a lateral magnification of the third sub-lens unit in an in-focus state at infinity.
7 . The zoom lens according to claim 1 , wherein the at least two lens units disposed in the middle group that move for zooming include, in order from the object side to the image side, a third lens unit, and a fourth lens unit having a positive refractive power, and
wherein a following inequality is satisfied:
0.3≤| f 4/ f 3|≤0.7
where f3 is a focal length of the third lens unit, and f4 is a focal length of the fourth lens unit.
8 . The zoom lens according to claim 1 , wherein the second sub-lens unit includes a positive lens, and
wherein a following inequality is satisfied:
15≤ν1 bp≤ 40
where ν1bp is an Abbe number with respect to d-line of the positive lens.
9 . The zoom lens according to claim 1 , wherein the third sub-lens unit moves for focusing.
10 . An image pickup apparatus comprising:
a zoom lens; and
an image pickup element configured to pick up an image formed by the zoom lens,
wherein the zoom lens includes, in order from an object side to an image side,
a first lens unit that has a positive refractive power and does not move for zooming;
a second lens unit that has a negative refractive power and moves in zooming;
a middle group that has at least two lens units that move in zooming; and
a final lens unit that has a positive refractive power, is disposed closest to the image side, and does not move for zooming,
wherein the zoom lens further comprises an aperture stop that is disposed between a surface closest to the image side of the second lens unit and a surface closest to the object side of the final lens unit, and moves in zooming,
wherein each distance between adjacent lens groups changes in zooming,
wherein the first lens unit includes, in order from the object side to the image side,
a first sub-lens unit that has a negative refractive power and does not move for focusing;
a second sub-lens unit that has a negative refractive power and moves for focusing; and
a third sub-lens unit having a positive refractive power,
wherein a distance between the second sub-lens unit and the third sub-lens unit changes for focusing,
wherein the second sub-lens unit includes a negative lens, and
wherein following inequalities are satisfied:
0.2
≤
flb
/
fla
≤
3
.
2
35
≤
vlbn
≤
100
0.3
≤
❘
"\[LeftBracketingBar]"
f
2
/
fl
❘
"\[RightBracketingBar]"
≤
0.8
0.08
≤
(
Lspt
-
Lspw
)
/
Skw
≤
0
.80
where f1a is a focal length of the first sub-lens unit, f1b is a focal length of the second sub-lens unit, νbn is an Abbe number with respect to d-line of the negative lens in the second sub-lens unit, f1 is a focal length of the first lens unit, and f2 is a focal length of the second lens unit, Lspw is a distance on an optical axis from a surface closest to the object side of the first lens unit to the aperture stop at a wide-angle end, Lspt is a distance on the optical axis from the surface closest to the object side of the first lens unit to the aperture stop at a telephoto end, and Skw is a distance on the optical axis from a surface closest to the image side of the final lens unit to an image plane.