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

1. A zoom optical system comprising, in order from an object:

a first lens group having positive refractive power;

a second lens group having negative refractive power;

a third lens group having positive refractive power; and

a subsequent lens group,

wherein

upon zooming, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, and a distance between the third lens group and the subsequent lens group changes,

the subsequent lens group comprises:

a focusing lens group that has negative refractive power and moves upon focusing;

a lens that is disposed to an image side of the focusing lens group, and has negative refractive power; and

a lens that is disposed to an image side of the lens having the negative refractive power, and has positive refractive power,

the following lens group comprises:

at least one lens having positive refractive power, and

at least one lens having negative refractive power, and

the following conditional expressions are satisfied:

0.18<(− fF )/ f 1<0.30

0.84<(− f 2)/ f 3<1.20

0.70<(− fN )/ fP< 2.00

where

fF: a focal length of the focusing lens group,

f1: a focal length of the first lens group,

f2: a focal length of the second lens group,

f3: a focal length of the third lens group,

fN: a focal length of the lens that is disposed to the image side of the focusing lens group and has negative refractive power, and

fP: a focal length of the lens that is disposed to the image side of the lens having the negative refractive power, and has positive refractive power.

2. The zoom optical system according to claim 1 , wherein

upon zooming from a wide-angle end state to a telephoto end state, the first lens group moves toward the object.

3. The zoom optical system according to claim 1 , wherein

the second lens group comprises a vibration-proof lens group movable so as to have a displacement component in a direction perpendicular to an optical axis in order to correct an image blur.

4. The zoom optical system according to claim 3 , wherein

the vibration-proof lens group consists of, in order from the object:

a lens having negative refractive power; and

a lens having positive refractive power.

5. The zoom optical system according to claim 4 , wherein

the following conditional expression is satisfied:

0.80< nN/nP< 1.00

where

nN: a refractive index of the lens having the negative refractive power in the vibration-proof lens group, and

nP: a refractive index of the lens having the positive refractive power in the vibration-proof lens group.

6. The zoom optical system according to claim 5 , wherein

the following conditional expression is satisfied:

1.20<ν N/νP< 2.40

where

vN: an Abbe number of the lens having negative refractive power in the vibration-proof lens group, and

vP: an Abbe number of the lens having positive refractive power in the vibration-proof lens group.

7. An optical apparatus comprising the zoom optical system according to claim 1 .

8. An imaging apparatus comprising:

the zoom optical system according to claim 1 ; and

an imaging unit that takes an image formed by the zoom optical system.

9. A zoom optical system comprising, in order from an object:

a first lens group having positive refractive power;

a second lens group having negative refractive power;

a third lens group having positive refractive power; and

a subsequent lens group,

wherein

upon zooming, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, and a distance between the third lens group and the subsequent lens group changes,

upon zooming from a wide-angle end state to a telephoto end state, the first lens group moves toward the object,

the subsequent lens group comprises a focusing lens group that has negative refractive power and moves upon focusing,

the focusing lens group comprises:

at least one lens having positive refractive power; and

at least one lens having negative refractive power, and

the following conditional expression is satisfied:

0.18<(− fF )/ f 1<0.30

where

fF: a focal length of the focusing lens group, and

f1: a focal length of the first lens group.

10. The zoom optical system according to claim 9 , wherein

the following conditional expression is satisfied:

0.80< nN/nP< 1.00

where

nN: a refractive index of the lens having the negative refractive power in the vibration-proof lens group, and

nP: a refractive index of the lens having the positive refractive power in the vibration-proof lens group.

11. The zoom optical system according to claim 9 , wherein

the following conditional expression is satisfied:

1.20<ν N/νP< 2.40

where

vN: an Abbe number of the lens having the negative refractive power in the vibration-proof lens group, and

vP: an Abbe number of the lens having the positive refractive power in the vibration-proof lens group.

12. The zoom optical system according to claim 9 , wherein

the subsequent lens group comprises:

a lens that is disposed to an image side of the focusing lens group, and has negative refractive power; and

a lens that is disposed to an image side of the lens having the negative refractive power, and has positive refractive power.

13. The zoom optical system according to claim 9 , wherein

the following conditional expression is satisfied:

0.70<(− fN )/ fP< 2.00

where

fN: a focal length of the lens that is disposed to the image side of the focusing lens group and has the negative refractive power, and

fP: a focal length of the lens that is disposed to the image side of the lens having the negative refractive power, and has positive refractive power.

14. An optical apparatus comprising the zoom optical system according to claim 9 .

15. An imaging apparatus comprising:

the zoom optical system according to claim 9 ; and

an imaging unit that takes an image formed by the zoom optical system.

16. A zoom optical system comprising, in order from an object:

a first lens group having positive refractive power;

a second lens group having negative refractive power;

a third lens group having positive refractive power; and

a subsequent lens group,

wherein

upon zooming, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, and a distance between the third lens group and the subsequent lens group changes,

upon zooming from a wide-angle end state to a telephoto end state, the first lens group moves toward the object,

the subsequent lens group comprises:

a focusing lens group that has negative refractive power and moves upon focusing;

a lens that is disposed to an image side of the focusing lens group, and has negative refractive power; and

a lens that is disposed to an image side of the lens having the negative refractive power, and has positive refractive power, and

the following conditional expressions are satisfied:

0.84<(− f 2)/ f 3<1.20

0.70<(− fN )/ fP< 1.80

where

f2: a focal length of the second lens group,

f3: a focal length of the third lens group,

fN: a focal length of the lens that is disposed to the image side of the focusing lens group and has the negative refractive power, and

fP: a focal length of the lens that is disposed to the image side of the lens having the negative refractive power, and has positive refractive power.

17. The zoom optical system according to claim 16 , wherein

the second lens group comprises a vibration-proof lens group movable so as to have a displacement component in a direction perpendicular to an optical axis in order to correct an image blur.

18. The zoom optical system according to claim 17 , wherein

the vibration-proof lens group consists of, in order from the object:

a lens having negative refractive power; and

a lens having positive refractive power.

19. An optical apparatus comprising the zoom optical system according to claim 16 .

20. An imaging apparatus comprising:

the zoom optical system according to claim 16 ; and

an imaging unit that takes an image formed by the zoom optical system.

21. A zoom optical system comprising, in order from an object:

a first lens group having positive refractive power;

a second lens group having negative refractive power;

a third lens group having positive refractive power; and

a subsequent lens group,

wherein

upon zooming, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, and a distance between the third lens group and the subsequent lens group changes,

the subsequent lens group comprises:

a focusing lens group that has negative refractive power and moves upon focusing;

a lens that is disposed to an image side of the focusing lens group, and has negative refractive power; and

a lens that is disposed to an image side of the lens having the negative refractive power, and has positive refractive power,

the focusing lens group comprises:

at least one lens having positive refractive power; and

at least one lens having negative refractive power, and

the following conditional expression is satisfied:

0.84<(− f 2)/ f 3<1.20

where

f2: a focal length of the second lens group, and

f3: a focal length of the third lens group.

22. An optical apparatus comprising the zoom optical system according to claim 21 .

23. An imaging apparatus comprising:

the zoom optical system according to claim 21 ; and

an imaging unit that takes an image formed by the zoom optical system.

24. A method for manufacturing a zoom optical system comprising, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a subsequent lens group, the method comprising:

arranging the lens groups in a lens barrel such that, upon zooming, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, and a distance between the third lens group and the subsequent lens group changes, and

the method further comprising one of the following features A, B, C and D, wherein

the feature A comprises:

configuring the subsequent lens group to comprise:

a focusing lens group that has negative refractive power and moves upon focusing;

a lens that is disposed to an image side of the focusing lens group, and has negative refractive power; and

a lens that is disposed to an image side of the lens having the negative refractive power, and has positive refractive power,

configuring the focusing lens group to comprise:

at least one lens having positive refractive power; and

at least one lens having negative refractive power, and

satisfying the following conditional expressions:

0.18<(− fF )/ f 1<0.30

0.84<(− f 2)/ f 3<1.20

0.70<(− fN )/ fP< 2.00

where

fF: a focal length of the focusing lens group,

f1: a focal length of the first lens group,

f2: a focal length of the second lens group,

f3: a focal length of the third lens group,

fN: a focal length of the lens that is disposed to the image side of the focusing lens group and has negative refractive power, and

fP: a focal length of the lens that is disposed to the image side of the lens having the negative refractive power, and has positive refractive power,

the feature B comprises:

arranging the lens groups in a lens barrel such that, upon zooming from a wide-angle end state to a telephoto end state, the first lens group moves toward the object;

configuring the subsequent lens group to comprise a focusing lens group that has negative refractive power and moves upon focusing;

configuring the focusing lens group to comprise:

at least one lens having positive refractive power; and

at least one lens having negative refractive power, and

satisfying the following conditional expression:

0.18<(− fF )/ f 1<0.30

where

fF: a focal length of the focusing lens group, and

f1: a focal length of the first lens group,

the feature C comprises:

arranging the lens groups in a lens barrel such that, upon zooming from a wide-angle end state to a telephoto end state, the first lens group moves toward the object,

configuring the subsequent lens group to comprise:

a focusing lens group that has negative refractive power and moves upon focusing;

a lens that is disposed to an image side of the focusing lens group, and has negative refractive power; and

a lens that is disposed to an image side of the lens having the negative refractive power, and has positive refractive power, and

satisfying the following conditional expressions:

0.84<(− f 2)/ f 3<1.20

0.70<(− fN )/ fP< 1.80

where

f2: a focal length of the second lens group,

f3: a focal length of the third lens group,

fN: a focal length of the lens that is disposed to the image side of the focusing lens group and has negative refractive power, and

fP: a focal length of the lens that is disposed to the image side of the lens having the negative refractive power, and has positive refractive power, and

the feature D comprises:

configuring the subsequent lens group to comprise:

a focusing lens group that has negative refractive power and moves upon focusing;

a lens that is disposed to an image side of the focusing lens group, and has negative refractive power; and

a lens that is disposed to an image side of the lens having the negative refractive power, and has positive refractive power,

configuring the focusing lens group to comprise:

at least one lens having positive refractive power; and

at least one lens having negative refractive power, and

satisfying the following conditional expression:

0.84<(− f 2)/ f 3<1.20

where

f2: a focal length of the second lens group, and

f3: a focal length of the third lens group.