Zoom lens, image pickup apparatus including the same, and control device for the same

Patent metadata

Field	Value
Publication number	US-10908400-B2
Application number	US-201715833340-A
Country	US
Kind code	B2
Filing date	Dec 6, 2017
Priority date	Dec 9, 2016
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

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; and a third lens unit having a positive refractive power. The first lens unit does not move and the second lens unit and the third lens unit move in mutually different loci during zooming. Conditional expressions are satisfied as follows:

0.05<| f 2/ m 2|<0.59, and

0.20<| f 3/ m 3|<1.95,

where f2 is a focal length of the second lens unit, f3 is a focal length of the third lens unit, m2 is a moving amount of the second lens unit during zooming from a wide-angle end to a telephoto end, and m3 is a moving amount of the third lens unit during zooming from the wide-angle end to the telephoto end.

First claim

What is claimed is:

1. A zoom lens consisting of, 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; and
a third lens unit having a positive refractive power,
wherein the first lens unit does not move and the second lens unit and the third lens unit move in mutually different loci during zooming, and
wherein conditional expressions are satisfied as follows:
0.45<| f 2/ m 2|<0.59, and
0.20<| f 3/ m 3|<1.95,

where f2 is a focal length of the second lens unit, f3 is a focal length of the third lens unit, m2 is a moving amount of the second lens unit during zooming from a wide-angle end to a telephoto end, and m3 is a moving amount of the third lens unit during zooming from the wide-angle end to the telephoto end.

2. The zoom lens according to claim 1 ,
wherein a conditional expression is satisfied as follows:
0.40<| f 2/ f 3|<1.20.

3. The zoom lens according to claim 1 , wherein the first lens unit includes a cemented lens in which a positive lens and a negative lens arranged on the image side of the positive lens are cemented.

4. The zoom lens according to claim 1 ,
wherein a conditional expression is satisfied as follows:
4.00<| f 1/ f 2|<20.00,

where f1 is a focal length of the first lens unit.

5. The zoom lens according to claim 1 ,
wherein the second lens unit includes at least two negative lenses, and
wherein a conditional expression is satisfied as follows:
1.70< nd 2 n< 2.30,

where nd2n is an average value of refractive indices of materials of negative lenses included in the second lens unit.

6. The zoom lens according to claim 1 ,
wherein the third lens unit includes at least two positive lenses, and
wherein a conditional expression is satisfied as follows:
60.00< νd 3 p< 98.00,

where νd3p is an Abbe number of a material having a largest Abbe number among Abbe numbers of materials of positive lenses included in the third lens unit.

7. The zoom lens according to claim 1 , further comprising:
an aperture stop arranged between the second lens unit and the third lens unit, the aperture stop configured not to move during zooming,
wherein a conditional expression is satisfied as follows:
0.030< d 23 t/TLt< 0.100,

where d23t is a distance on an optical axis between the second lens unit and the third lens unit at the telephoto end, and TLt is a total length of the zoom lens at the telephoto end.

8. 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 positive lens, a cemented lens in which a positive lens and a negative lens are cemented, and a positive lens.

9. 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 positive lens, a negative lens, and a positive lens.

10. An image pickup apparatus comprising:
the zoom lens according to claim 1 ; and
an image pickup device configured to receive light from the zoom lens.

11. A control device configured to control the zoom lens of claim 1 , comprising:
a control unit configured to control the zoom lens so that the conditional expressions in claim 1 are satisfied during zooming.

12. The control device according to claim 11 , further comprising an operation unit configured to operate the zoom lens.

13. The control device according to claim 11 , further comprising a display unit configured to display information relating to zooming of the zoom lens.

14. A zoom lens consisting of, 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; and
a third lens unit having a positive refractive power,
wherein a distance between adjacent ones of the lens units is changed during zooming from a wide-angle end to a telephoto end so that a distance between the first lens unit and the second lens unit is increased and a distance between the second lens unit and the third lens unit is decreased,
wherein the first lens unit consists of, in order from the object side to the image side, a positive lens and a negative lens,
wherein the second lens unit includes two negative lenses, and
wherein a conditional expression is satisfied as follows:
7.00< f 1/ fw< 30.00,

where f1 is a focal length of the first lens unit, and fw is a focal length of the zoom lens at the wide-angle end.

15. The zoom lens according to claim 14 , wherein the first lens unit consists of a cemented lens in which a positive lens and a negative lens are cemented, and a cemented surface of the cemented lens has a shape convex toward the image side.

16. The zoom lens according to claim 14 , further comprising an aperture stop arranged between the second lens unit and the third lens unit, the aperture stop configured not to move during zooming.

17. The zoom lens according to claim 14 ,
wherein a conditional expression is satisfied as follows:
2.00< f 1/ L 12 t< 5.00,

where L 12 t is a distance from a lens surface vertex on a most image side of the first lens unit to a lens surface vertex on a most object side of the second lens unit at the telephoto end.

18. The zoom lens according to claim 14 ,
wherein a conditional expression is satisfied as follows:
1.75<( Ndp+Ndn )/2<2.30,

where Ndp is a refractive index of the positive lens included in the first lens unit for a d-line, and Ndn is a refractive index of the negative lens included in the first lens unit for the d-line.

19. The zoom lens according to claim 14 ,
wherein a conditional expression is satisfied as follows:
−1.00<( r 1+ r 2)/( r 1− r 2)<0.50,

where r1 is a curvature radius of a lens surface on the object side of the positive lens included in the first lens unit, and r2 is a curvature radius of a lens surface on the image side of the positive lens included in the first lens unit.

20. 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; and
a third lens unit having a positive refractive power,
wherein a distance between adjacent ones of the lens units is changed during zooming, wherein the second lens unit includes a negative lens G2n arranged on a most object side in the second lens unit, a positive lens, a negative lens, and
wherein conditional expressions are satisfied as follows:
1.91< nd 2 n< 2.40,
−1.50<( R 2+ R 1)/( R 2− R 1)<−0.10, and

1.00<| f 2/ fw|< 4.00,

where R1 is a curvature radius of a lens surface on the object side of the negative lens G2n, R2 is a curvature radius of a lens surface on the image side of the negative lens G2n, nd2n is a refractive index of a material of the negative lens G2n for a d-line, f2 is a focal length of the second lens unit, and fw is a focal length of the zoom lens at a wide-angle end.

21. The zoom lens according to claim 20 ,
wherein a conditional expression is satisfied as follows:
1.50< f 3/ fw< 5.00,

where f3 is a focal length of the third lens unit, and fw is a focal length of the zoom lens at a wide-angle end.

22. The zoom lens according to claim 20 ,
wherein a conditional expression is satisfied as follows:
7.00< f 1/ fw< 30.00,

where f1 is a focal length of the first lens unit, and fw is a focal length of the zoom lens at a wide-angle end.

Assignees

• Canon Kk

Inventors

• Sudo Kenta
• Abe Hirofumi
• Inomoto Yu

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

• G02B15/173 Primary

  arranged +-+ · CPC title

• G02B15/143105 Primary

  arranged +-+ · CPC title

• G02B15/28 Primary

  arranged +-+ · CPC title