Zoom lens and image pickup apparatus including the same

Patent metadata

Field	Value
Publication number	US-11249290-B2
Application number	US-202016825924-A
Country	US
Kind code	B2
Filing date	Mar 20, 2020
Priority date	Mar 26, 2019
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

Provided is a zoom lens including, 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 fourth lens unit having a negative refractive power. In the zoom lens, an interval between each pair of adjacent lens units is changed during zooming, and the first lens unit is configured not to move for zooming. Further, a total length DT of the zoom lens at a telephoto end, a focal length fT of the zoom lens at the telephoto end, a distance BW of a back focus at a wide-angle end, a total length DW of the zoom lens at the wide-angle end, and a focal length f3 of the third lens unit are each appropriately set.

First claim

What is claimed is:

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 fourth lens unit having a negative refractive power,
wherein an interval between each pair of adjacent lens units is changed during zooming,
wherein the first lens unit is configured not to move for zooming, and
wherein the following inequalities are satisfied:
0.30< DT/fT< 0.85;
0.02< BW/DW< 0.14; and
0.145< f 3/ fT< 0.450,

where DT is a total length of the zoom lens at a telephoto end, fT is a focal length of the zoom lens at the telephoto end, BW is a distance of a back focus at a wide-angle end, DW is a total length of the zoom lens at the wide-angle end, and f3 is a focal length of the third lens unit.

2. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
−2.0< f 3/ f 4<−0.4,

where f4 is a focal length of the fourth lens unit.

3. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.31< f 3/ f 1<0.80,
where f1 is a focal length of the first lens unit.

4. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
−1.50< f 3/ f 2<−0.70,

where f2 is a focal length of the second lens unit.

5. The zoom lens according to claim 1 , wherein the following inequality is satisfied:
−0.60< f 4/ fT<− 0.08,

where f4 is a focal length of the fourth lens unit.

6. The zoom lens according to claim 1 , wherein at least a part of the third lens unit is configured to move in a direction having a component perpendicular to an optical axis for image stabilization.

7. The zoom lens according to claim 1 , wherein the third lens unit consists of, in order from the object side to the image side, a cemented lens formed by cementing a positive lens and a negative lens, and a positive lens.

8. The zoom lens according to claim 1 , wherein the third lens unit includes an aperture stop.

9. The zoom lens according to claim 1 , wherein the third lens unit is configured not to move for zooming.

10. The zoom lens according to claim 1 , wherein at least a part of the fourth lens unit is configured to move for focusing.

11. The zoom lens according to claim 1 , wherein the fourth lens unit consists of, in order from the object side to the image side, a positive lens and a negative lens.

12. The zoom lens according to claim 1 , further comprising a fifth lens unit having one of a positive refractive power and a negative refractive power, which is arranged adjacent to, and on the image side of, the fourth lens unit.

13. An image pickup apparatus comprising:
a zoom lens; and
an image pickup element configured to receive an optical image formed through the zoom lens,
the zoom lens including, 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 fourth lens unit having a negative refractive power,

wherein an interval between each pair of adjacent lens units is changed during zooming,
wherein the first lens unit is configured not to move for zooming, and
wherein the following inequalities are satisfied:
0.30< DT/fT< 0.85;
0.02< BW/DW< 0.14; and
0.145< f 3/ fT< 0.450,

where DT is a total length of the zoom lens at a telephoto end, fT is a focal length of the zoom lens at the telephoto end, BW is a distance of a back focus at a wide-angle end, DW is a total length of the zoom lens at the wide-angle end, and f3 is a focal length of the third lens unit.

14. The image pickup apparatus according to claim 13 , wherein in the zoom lens, the following inequality is satisfied:
−2.0< f 3/ f 4<−0.4,

where f4 is a focal length of the fourth lens unit.

15. The image pickup apparatus according to claim 13 , wherein in the zoom lens, the following inequality is satisfied:
0.31< f 3/ f 1<0.80,
where f1 is a focal length of the first lens unit.

16. The image pickup apparatus according to claim 13 , wherein in the zoom lens, the following inequality is satisfied:
−1.50< f 3/ f 2<−0.70,

where f2 is a focal length of the second lens unit.

17. The image pickup apparatus according to claim 13 , wherein jn the zoom lens, the following inequality is satisfied:
−0.60< f 4/ fT<− 0.08,

where f4 is a focal length of the fourth lens unit.

18. The image pickup apparatus according to claim 13 , wherein at least a part of the third lens unit is configured to move in a direction having a component perpendicular to an optical axis for image stabilization.

19. The image pickup apparatus according to claim 13 , wherein the third lens unit includes, in order from the object side to the image side, a cemented lens formed by cementing a positive lens and a negative lens, and a positive lens.

20. The image pickup apparatus according to claim 13 , wherein the third lens unit includes an aperture stop.

Assignees

• Canon Kk

Inventors

• Aoki Koji

Classifications

• H04N23/55

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• H04N23/69

  Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming · CPC title

• G02B15/145121

  arranged +-+-+ · CPC title

• G02B15/144105 Primary

  arranged +-+- · CPC title

• G02B9/34

  having four components only · CPC title