Zoom optical system, optical apparatus and method for manufacturing the zoom optical system

Patent metadata

Field	Value
Publication number	US-12085701-B2
Application number	US-202117495657-A
Country	US
Kind code	B2
Filing date	Oct 6, 2021
Priority date	Oct 7, 2016
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

A zoom optical system (ZL) comprises a first negative lens group (G2) having a negative refractive power; and a second negative lens group (G4) disposed closer to an image than the first negative lens group (G2), wherein a distance between the first negative lens group (G2) and the second negative lens group (G4) changes during zooming, at least part of the first negative lens group (G2) is movable so as to have a displacement component in a direction perpendicular to an optical axis, at least part of the second negative lens group (G4) is movable along the optical axis during focusing, and the following conditional expression,0.50<fGb/fGa<2.60is satisfied,where,fGa: a focal length of the first negative lens group (G2), andfGb: a focal length of the second negative lens group (G4).

First claim

The invention claimed is:

1. A zoom optical system comprising:
a first negative lens group having a negative refractive power,
a second negative lens group having a negative refractive power and disposed closer to an image than the first negative lens group, and
an object side lens group disposed on the object side with respect to the first negative lens group and having a positive refractive power,
wherein a distance between the first negative lens group and the second negative lens group and a distance between the object side lens group and the first negative lens group change during zooming,
at least part of the first negative lens group is movable so as to have a displacement component in a direction perpendicular to an optical axis,
at least part of the second negative lens group is movable along the optical axis during focusing, and
the following conditional expressions are satisfied:
0.50< fGb/fGa< 2.60
0.30<| mda|/fw< 2.30

where
fGa: a focal length of the first negative lens group,
fGb: a focal length of the second negative lens group,
|mda|: an absolute value of the amount of change in distance from a lens surface closest to an image in the object side lens group to a lens surface closest to an object in the first negative lens group on the optical axis during zooming from a wide angle end state to a telephoto end state, and
fw: a focal length of the zoom optical system in the wide angle end state.

2. The zoom optical system according to claim 1 , comprising
an intermediate lens group disposed between the first negative lens group and the second negative lens group,
wherein a distance between the first negative lens group and the intermediate lens group and a distance between the intermediate lens group and the second negative lens group change during zooming.

3. The zoom optical system according to claim 1 , comprising
an image side lens group disposed closer to an image than the second negative lens group, wherein
during zooming, a distance between the second negative lens group and the image side lens group changes.

4. The zoom optical system according to claim 1 , comprising
an intermediate lens group disposed between the first negative lens group and the second negative lens group,
wherein a distance between the first negative lens group and the intermediate lens group and a distance between the intermediate lens group and the second negative lens group change during zooming, and
an aperture stop is disposed between the first negative lens group and the intermediate lens group.

5. The zoom optical system according to claim 1 , further comprising a positive lens group having a positive refractive power, which is disposed between the first negative lens group and the second negative lens group, and
wherein a distance between the first negative lens group and the positive lens group and a distance between the positive lens group and the second negative lens group change during zooming.

6. The zoom optical system according to claim 1 , wherein the second negative lens group consists of a cemented lens of a positive lens and a negative lens.

7. The zoom optical system according to claim 1 , further comprising a first positive lens group having a positive refractive power, which is disposed closest to an object, and
the first positive lens group consists of, in order from an object side, a positive lens, a negative lens and a positive lens.

8. The zoom optical system according to claim 1 , wherein
the second negative lens group comprises a positive lens and a negative lens disposed in order from an object,
an air distance is present between the positive lens and the negative lens, and
the following conditional expression is satisfied:
0.001< Dpn /(− fGb )<0.400

where
Dpn: an air distance between the positive lens and the negative lens in the second negative lens group.

9. The zoom optical system according to claim 1 , wherein
the first negative lens group comprises at least partly a vibration proof group movable so as to have a displacement component in a direction perpendicular to an optical axis, and
the vibration proof group consists of a positive lens, a first negative lens, and a second negative lens disposed in order from an object,
an air distance is present between the positive lens and the first negative lens, and
an air distance is present between the first negative lens and the second negative lens.

10. A zoom optical system comprising:
a first negative lens group having a negative refractive power,
a second negative lens group having a negative refractive power and disposed closer to an image than the first negative lens group, and
an intermediate lens group disposed between the first negative lens group and the second negative lens group,
wherein a distance between the first negative lens group and the second negative lens group, a distance between the first negative lens group and the intermediate lens group and a distance between the intermediate lens group and the second negative lens group change during zooming,
at least part of the first negative lens group is movable so as to have a displacement component in a direction perpendicular to an optical axis,
at least part of the second negative lens group is movable along the optical axis during focusing, and
the following conditional expressions are satisfied:
0.50< fGb/fGa< 2.60
0.050<| mcb|/fw< 0.750

where
fGa: a focal length of the first negative lens group,
fGb: a focal length of the second negative lens group,
|mcb|: an absolute value of the amount of change in distance from a lens surface closest to an image in the intermediate lens group to a lens surface closest to an object in the second negative lens group on the optical axis during zooming from a wide angle end state to a telephoto end state, and
fw: a focal length of the zoom optical system in the wide angle end state.

11. The zoom optical system according to claim 10 , comprising
an image side lens group disposed closer to an image than the second negative lens group, wherein
during zooming, a distance between the second negative lens group and the image side lens group changes.

12. The zoom optical system according to claim 10 , wherein the second negative lens group consists of a cemented lens of a positive lens and a negative lens.

13. The zoom optical system according to claim 10 , further comprising a first positive lens group having a positive refractive power, which is disposed closest to an object, and
the first positive lens group consists of, in order from an object side, a positive lens, a negative lens and a positive lens.

14. The zoom optical system according to claim 10 , wherein
the intermediate lens group consists of an object side subgroup having a positive refractive power and an image side subgroup having a positive refractive power disposed in order from an object,
a lens component including a negative lens is disposed at a position closest to the object in the image side subgroup, and
the following conditional expression is satisfied:
0.06< fa/fb< 1.20

where
fa: a focal length of the object side subgroup, and
fb: a focal length of the image side subgroup.

15. The zoom optical system according to claim 10 , wherein
the intermediate lens group consists of an object side subgroup having a positive refractive power and an image side subgroup having a positive refractive power disposed in order from an object,
an air distance between the object side subgroup and the image side subgroup is the maximum air distance between lens

Assignees

• Nikon Corp

Inventors

• Umeda Takeshi
• Ito Tomoki
• Shibayama Atsushi

Classifications

• G02B27/646

  compensating for small deviations, e.g. due to vibration or shake (movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68) · 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

• G02B15/20 Primary

  having an additional movable lens or lens group for varying the objective focal length · CPC title

• G02B15/177 Primary

  having a negative front lens or group of lenses · CPC title