Zoom lens and image pickup apparatus having the same
A zoom lens includes, in order from an object side to an image side, 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 fourth lens unit with a positive refractive power. During zooming from a wide-angle end to a telephoto end, the first lens unit moves, the second lens unit is fixed, a distance between the first lens unit and the second lens unit is widened, a distance between the second lens unit and the third lens unit is narrowed, and a distance between the third lens unit and the fourth lens unit is narrowed. The first lens unit includes a positive lens and a negative lens. Each of the second, third, and fourth lens units consists of two lenses or less.
1. A zoom lens comprising, in order from an object side to an image side, 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, fourth lens unit with a positive refractive power, and a fifth lens unit with a negative refractive power,
wherein during zooming from a wide-angle end to a telephoto end, the first lens unit moves, the second lens unit does not move along an optical axis, a distance between the first lens unit and the second lens unit is widened, a distance between the second lens unit and the third lens unit is narrowed, and a distance between the third lens unit and the fourth lens unit is narrowed,
wherein the first lens unit includes a positive lens and a negative lens,
wherein the second lens unit consists of two lenses or less,
wherein the third lens unit consists of two lenses or less,
wherein the fourth lens unit consists of two lenses or less, and
wherein during image stabilization, the second lens unit moves to include a component of a direction perpendicular to the optical axis,
wherein the following inequality is satisfied:
0.25< fL 3/ ft< 0.90
where fL3 is a focal length of the third lens unit, and ft is a focal length at the telephoto end of the zoom lens.
2. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.10< TLt/ft< 0.80
where TLt is an overall optical length of the zoom lens at the telephoto end.
3. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
1.40< ndL 4ave<1.70
where ndL4ave is an average of refractive index of lenses included in the fourth lens unit.
4. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
-0.30< fL 2/ ft<− 0.10
where fL2 is a focal length of the second lens unit.
5. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.3< ML 4/ ML 1<3.0
where ML1 is a moving amount of the first lens unit and ML4 is a moving amount of the fourth lens unit during zooming from the wide-angle end to the telephoto end.
6. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
-0.80< fL 2/ fL 1<−0.20
where fL1 is a focal length of the first lens unit, and fL2 is a focal length of the second lens unit.
7. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.05< fL 4/ ft< 0.50
where fL4 is a focal length of the fourth lens unit.
8. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.10< fL 4/ fL 1<0.70
where fL1 is a focal length of the first lens unit, and fL4 is a focal length of the fourth lens unit.
9. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.05< fL 4/ fL 3<1.00
where fL3 is a focal length of the third lens unit, and fL4 is a focal length of the fourth lens unit.
10. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.90< SL 4ave<2.80
where SL4ave is an average specific gravity of one or more lenses included in the fourth lens unit.
11. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
55< vdL 1 P ave<99
where vdL1Pave is an average value of an Abbe number for d-line of one or more positive lenses included in the first lens unit.
12. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
55< vdL 3 P ave<99
where vdL3Pave is an average value of an Abbe number for d-line of one or more positive lenses included in the third lens unit.
13. The zoom lens according to claim 1 , wherein the second lens unit consists of two lenses that are a negative lens and a positive lens arranged in order from the object side to the image side.
14. The zoom lens according to claim 1 , wherein the fourth lens unit includes a lens having at least one aspherical surface.
15. The zoom lens according to claim 1 , further comprising:
a diaphragm; and
a focus lens unit located closer to an image plane than the diaphragm and configured to perform focusing from infinity to a close end.
16. The zoom lens according to claim 1 , wherein the second lens unit consists of a positive lens A and a negative lens B, and the positive lens A and the negative lens are cemented.
17. The zoom lens according to claim 1 , wherein the third lens unit includes a negative meniscus lens having a concave surface towards the object side.
18. The zoom lens according to claim 1 , wherein the fourth lens unit includes a negative meniscus lens having a concave surface towards the object side.
19. The zoom lens according to claim 1 , wherein a total number of lens units which are arranged in the zoom lens is five.
20. An image pickup apparatus comprising:
a zoom lens; and
an image sensor configured to receive 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 with a positive refractive power, a second lens unit with a negative refractive power, a third lens unit with a positive refractive power, a fourth lens unit with a positive refractive power, and a fifth lens unit with a negative refractive power,
wherein during zooming from a wide-angle end to a telephoto end, the first lens unit moves, the second lens unit does not move along an optical axis, a distance between the first lens unit and the second lens unit is widened, a distance between the second lens unit and the third lens unit is narrowed, and a distance between the third lens unit and the fourth lens unit is narrowed,
wherein the first lens unit has a positive lens and a negative lens,
wherein the second lens unit consists of two lenses or less,
wherein the third lens unit consists of two lenses or less,
wherein the fourth lens unit consists of two lenses or less, and
wherein during image stabilization, the second lens unit moves to include a component of a direction perpendicular to the optical axis,
wherein the following inequality is satisfied:
0.25< fL 3/ ft< 0.90
where fL3 is a focal length of the third lens unit, and ft is a focal length at the telephoto end of the zoom lens.