Zoom lens and image pickup apparatus
A zoom lens includes, 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 having a plurality of lens units, and distances change between adjacent lens units during zooming. A predetermined condition is satisfied.
1. A zoom lens comprising, 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 group having a plurality of lens units,
wherein the rear group includes a lens unit LR closest to an image plane,
wherein each distance between adjacent lens units changes during zooming,
wherein a lens disposed closest to the image side in the zoom lens is a biconvex lens, and
wherein the following inequalities are satisfied:
−4.0< mr/bfw<− 1.5
−7.0< m 3/ bfw<− 2.5
where mr is a difference between a position of the lens unit LR relative to the image plane at the telephoto end and a position of the lens unit LR relative to the image plane at a wide-angle end, a sign of mr being negative when the lens unit LR is positioned closer to the object side at the telephoto end than at the wide-angle end, bfw is a distance on an optical axis from a surface closest to the image plane of the lens unit LR to the image plane at the wide-angle end, m3 is a difference between a position of the third lens unit relative to the image plane at the telephoto end and a position of the third lens unit relative to the image plane at the wide-angle end, a sign of m3 being negative when the third lens unit is positioned closer to the object side at the telephoto end than at the wide-angle end.
2. The zoom lens according to claim 1 , wherein the rear group includes at least three lens units.
3. The zoom lens according to claim 1 , wherein the first lens unit includes one negative lens and three positive lenses.
4. The zoom lens according to claim 1 , wherein during zooming from the wide-angle end to the telephoto end, the lens unit LR moves to the object side and then to the image side.
5. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.3< fr/f 1<2.8
where fr is a focal length of the lens unit LR, and f1 is a focal length of the first lens unit.
6. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
−9.0 <f 1 /f 2<−3.5
where f2 is a focal length of the second lens unit, and f1 is a focal length of the first lens unit.
7. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
−1.2< m 1/ f 1<−0.4
where m1 is a moving amount of the first lens unit during zooming from the wide-angle end to the telephoto end, and f1 is a focal length of the first lens unit.
8. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
3.0<β2 t/β 2 w< 12.0
where β2t is a lateral magnification of the second lens unit at the telephoto end, and β2w is a lateral magnification of the second lens unit at the wide-angle end.
9. The zoom lens according to claim 1 , further comprising a diaphragm,
wherein the following inequality is satisfied:
2.0< dpw/fw< 7.0
where dpw is a distance on the optical axis from the diaphragm to the image plane at the wide-angle end, and fw is a focal length of the zoom lens at the wide-angle end.
10. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.4< Lt/ft< 1.2
where Lt is a distance on the optical axis from a surface of the zoom lens closest to an object to the image plane at the telephoto end, and ft is a focal length of the zoom lens at a telephoto end.
11. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
2.0 <VdLR< 50.0
where VdLR is an Abbe number of the biconvex lens.
12. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.20 <f 1 /ft< 0.40
where f1 is a focal length of the first lens unit, and ft is a focal length of the zoom lens at a telephoto end.
13. An image pickup apparatus comprising:
the zoom lens according to claim 1 ; and
an image sensor configured to receive an image formed by the zoom lens.