Zoom optical system, optical apparatus and method for manufacturing the zoom optical system
A zoom optical system (ZL) comprises: a first lens group (G 1 ) disposed closest to an object and having a positive refractive power; an aperture stop (S) disposed closer to an image than the first lens group (G 1 ); a positive lens component disposed so as to oppose the image side of the aperture stop (S); and a lens group (G 3 ) having the positive lens component, wherein a distance between the first lens group (G 1 ) and the lens group (G 3 ) having the positive lens component changes during zooming, at least one lens surface of the positive lens component has an aspherical surface, and the following conditional expression, 0.40< fp/fGp <3.60 is satisfied, where fp: a focal length of the positive lens component, and fGp: a focal length of the lens group (G 3 ) having the positive lens component.
1. A zoom optical system comprising:
a first lens group having a positive refractive power, a second lens group disposed on an image side of the first lens group and having a negative refractive power, a third lens group disposed on an image side of the second lens group and having a positive refractive power, a fourth lens group disposed on an image side of the third lens group and having a negative refractive power, and a final lens group disposed on an image side of the fourth lens group and also disposed closest to an image,
wherein
a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the fourth lens group change during zooming,
the first lens group is moved along an optical axis during zooming,
the second lens group comprises a vibration proof group capable of moving with a displacement component in a direction perpendicular to the optical axis and having a negative refractive power, and
the following conditional expression is satisfied:
0.30<| m 12|/ fw< 2.30
where
|m12|: an absolute value of the amount of change in distance from a lens surface closest to the image in the first lens group to a lens surface closest to the object in the second 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 ,
further comprising an aperture stop disposed on an image side of the second lens group.
3. The zoom optical system according to claim 2 , wherein a positive lens is disposed on an image side of the aperture stop.
4. The zoom optical system according to claim 1 , including a focusing lens group having a negative refractive power, the focusing lens group being moved along the optical axis during focusing.
5. The zoom optical system according to claim 4 , wherein the final lens group is disposed on an image side of the focusing lens group.
6. The zoom optical system according to claim 1 , wherein the final lens group has a negative refractive power.
7. The zoom optical system according to claim 1 , wherein
the following conditional expression is satisfied:
0.93< fVR/f 2<2.50
where
fVR: a focal length of the vibration proof group, and
f2: a focal length of the second lens group.
8. The zoom optical system according to claim 1 , wherein
the following conditional expression is satisfied:
0.40< f 3/(− f 2)<2.60
where
f2: a focal length of the second lens group, and
f3: a focal length of the third lens group.
9. The zoom optical system according to claim 1 , wherein
the following conditional expression is satisfied:
0.40< f 3/(− f 4)<2.40
where
f3: a focal length of the third lens group, and
f4: a focal length of the fourth lens group.
10. An optical apparatus comprising the zoom optical system according to claim 1 .
11. A method for manufacturing a zoom optical system, comprising:
arranging, in a lens barrel, a first lens group having a positive refractive power, a second lens group disposed on an image side of the first lens group and having a negative refractive power, a third lens group disposed on an image side of the second lens group and having a positive refractive power, a fourth lens group disposed on an image side of the third lens group and having a negative refractive power, and a final lens group disposed on an image side of the fourth lens group and also disposed closest to an image,
arranging the first to fourth lens groups such that a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the fourth lens group change during zooming,
arranging the first lens group to be movable along an optical axis during zooming,
configuring the second lens group to comprise a vibration proof group capable of moving with a displacement component in a direction perpendicular to the optical axis and having a negative refractive power, and
configuring such that the following conditional expression is satisfied:
0.30<| m 12|/ fw< 2.30
where
|m12|: an absolute value of the amount of change in distance from a lens surface closest to the image in the first lens group to a lens surface closest to the object in the second 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.