Zoom lens and image pickup apparatus using the same

Patent metadata

Field	Value
Publication number	US-10338359-B2
Application number	US-201715480633-A
Country	US
Kind code	B2
Filing date	Apr 6, 2017
Priority date	Apr 11, 2016
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

Provided is a small zoom lens having a high zoom ratio and easily designed to achieve favorable optical properties in an entire zooming range. A zoom lens includes, in order from object side to image side, a positive first unit, a negative second unit, an aperture stop, and a rear group including multiple units. Intervals between the adjacent units are changed during zooming. In the rear group, a positive lens unit is arranged on the most image side, and a negative lens unit is on the object side of the positive lens unit. The aperture stop not moving for zooming, but the second unit and the negative lens unit moving during zooming. Focal lengths of the second unit and the positive and negative lens units, and movement amounts of the second and negative lens units, respectively, during zooming from wide angle end to telephoto end are 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, an aperture stop, and a rear group including a plurality of lens units, wherein
intervals between the adjacent lens units are changed during zooming,
in the rear group, a lens unit Lp having a positive refractive power is arranged closest to an image side, a lens unit Ln having a negative refractive power is arranged on the object side of and adjacent to the lens unit Lp, and a third lens unit having a positive refractive power is arranged closest to the object side,
the aperture stop does not move for zooming, but the second lens unit and the lens unit Ln move during zooming,
the first lens unit consists of, in order from the object side to the image side, a negative lens, a positive lens, a positive lens, and a positive lens, and
the zoom lens satisfies the following conditional expressions:
−6.00< f 2/| M 2|<−0.02; and

−1.80< fn/|Mn|<− 0.02,

where f2 denotes a focal length of the second lens unit, fn denotes a focal length of the lens unit Ln, M2 denotes a movement amount of the second lens unit during zooming from a wide angle end to a telephoto end, and Mn denotes a movement amount of the lens unit Ln during zooming from the wide angle end to the telephoto end.

2. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression:
0.7 <f 2 /fn< 2.0.

3. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression:
−5.0<(1−β nT 2 )×β pT 2 <−2.0,

where βnT denotes a lateral magnification of the lens unit Ln at the telephoto end, and βpT denotes a lateral magnification of the lens unit Lp at the telephoto end.

4. The zoom lens according to claim 1 , wherein
the lens unit Ln consists of a single negative lens, and
the single negative lens satisfies the following conditional expression:
1.7< ndn< 2.1,

where ndn denotes a refractive power of a material for the single negative lens.

5. The zoom lens according to claim 1 , wherein
the lens unit Lp consists of a single positive lens, and
the single positive lens satisfies the following conditional expression:
1.5< ndp< 1.9,

where ndp denotes a refractive power of a material of the single positive lens.

6. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression:
2.5< f 1/ f 3<6.0,
where f1 denotes a focal length of the first lens unit, and f3 denotes a focal length of the third lens unit.

7. The zoom lens according to claim 1 , wherein
the third lens unit satisfies the following conditional expression:
1.2< f 3/| M 3|<4.0,

where f3 denotes a focal length of the third lens unit, and M3 denotes a movement amount of the third lens unit during zooming from the wide angle end to the telephoto end.

8. The zoom lens according to claim 1 , wherein
the third lens unit moves during zooming.

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

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

11. The zoom lens according to claim 1 , wherein
the third lens unit consists of a positive lens.

12. 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, a positive lens, and a positive lens.

13. The zoom lens according to claim 1 , wherein
the rear group consists of, in order from the object side to the image side, the third lens unit, a fourth lens unit having a positive refractive power, a fifth lens unit having a negative refractive power, and a sixth lens unit having a positive refractive power.

14. The zoom lens according to claim 1 , wherein
the rear group consists of, in order from the object side to the image side, the third lens unit, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power.

15. 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, an aperture stop, and a rear group including a plurality of lens units,
wherein intervals between the adjacent lens units are changed during zooming,
in the rear group, a lens unit Lp having a positive refractive power is arranged closest to an image side, a lens unit Ln having a negative refractive power is arranged on the object side of and adjacent to the lens unit Lp, and a third lens unit having a positive refractive power is arranged closest to the object side,
the first lens unit does not move for zooming, but the second lens unit and the lens unit Ln move during zooming,
the zoom lens satisfies the following conditional expressions:
1.10<β nT/βnW< 1.70;

0.20< drt/|M 2|<1.30; and
0.01 <dnpw/drw< 0.40,

where βnW denotes a lateral magnification of the lens unit Ln at a wide angle end, βnT denotes the lateral magnification of the lens unit Ln at a telephoto end, M2 denotes a movement amount of the second lens unit during zooming from the wide angle end to the telephoto end, dnpw denotes a distance in an optical axis direction from the lens surface of the lens unit Ln closest to an object side to the lens surface of the lens unit Lp closest to the image side at the wide angle end, drw denotes a distance in the optical axis direction from the aperture stop to the image plane at the wide angle end, and drt denotes a distance in the optical axis direction from the aperture stop to the image plane at the telephoto end.

16. The zoom lens according to claim 15 , wherein
the zoom lens satisfies the following conditional expression:
−4.0< f 2/ fw<− 1.0,

where f2 denotes a focal length of the second lens unit, and fw denotes a focal length of the zoom lens at the wide angle end.

17. The zoom lens according to claim 15 , wherein
the zoom lens satisfies the following conditional expression:
−0.10< fn/ft<− 0.01,

where fn denotes a focal length of the lens unit Ln, and ft denotes a focal length of the zoom lens at the telephoto end.

18. 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, an aperture stop, and a rear group including a plurality of lens units,
wherein intervals between the adjacent lens units are changed during zooming,
in the rear group, a lens unit Lp having a positive refractive power is arranged closest to an image side, a lens unit Ln having a negative refractive power is arranged on the object side of and adjacent to the lens unit Lp, and a third lens unit having a positive refractive power is arranged closest to the object side,
the first lens unit does not move for zooming, but the second lens unit and the lens unit Ln move during zooming,
the first lens unit includes a negative lens and two or more positive lenses, and
the zoom lens satisfies the following conditional expressions:
4.5<| f 1/ fn|< 10.0; and
0.01 <dnpw/drw< 0.40,

where f1 denotes a focal length of the first lens unit, fn denotes

Assignees

• Canon Kk

Inventors

• Kuwashiro Shin
• Inomoto Yu

Classifications

• G02B5/005

  Diaphragms (for cameras G03B9/02) · CPC title

• G02B13/009

  having zoom function · CPC title

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B27/0025

  for optical correction, e.g. distorsion, aberration · CPC title

• G02B13/0045

  having five or more lenses · CPC title