Optical system, optical apparatus, and method for manufacturing optical system
AssigneeNikon Corporation
InventorsTomoki Ito, Issei Tanaka
Life of this patent
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Abstract
An optical system includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. The second lens group is moved upon carrying out focusing from an infinitely distant object to a close object, at least a portion of the third lens group is moved in a direction including a component perpendicular to an optical axis, and given conditional expressions is satisfied. Accordingly, an optical system excellently suppressing variations in aberrations generated upon vibration reduction, an optical apparatus equipped therewith, and a method for manufacturing the optical system are provided.
Claims24
An optical system comprising, in order from an object side:
- a first lens group having positive refractive power;
- a second lens group having negative refractive power;
- and
- a third lens group having positive refractive power,
- the second lens group being moved upon carrying out focusing from an infinitely distant object to a close object,
- at least a portion of the third lens group being movable in a direction including a component perpendicular to an optical axis,
- the at least a portion of the third lens group being a negative lens group having refactive power, and
- the following conditional expressions being satisfied:
- 0.30<f1/f<0.60
- 0.20<(−f2)/f<0.60
- 0.30<f3/f<0.60
- 0.50<(−fVR)/f3<1.00
- where f denotes a focal length of the optical system, f1 denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, f3 denotes a focal length of the third lens group, and fVR denotes a focal length of the negative lens group in the third lens group.
A method for manufacturing an optical system including, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power, the method comprising steps of:
- disposing the first lens group, the second lens group and the third lens group with satisfying the following conditional expressions:
- 0.30<f1/f<0.60
- 0.20<(−f2) /f<0.60
- 0.30<f3/f<0.60
- where f denotes a focal length of the optical system, fl denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, and f3 denotes a focal length of the third lens group;
- disposing the second lens group to be movable upon carrying out focusing from an infinitely distant object to a close object;
- and
- disposing at least a portion of the third lens group to be movable in a direction including a component perpendicular to an optical axis,
- the at least apportion of the third lens group being a negative lens group having negative refractive power, and
- the following conditional expression being satisfied:
- 0.50<(−fVR)/f3<1.00
- where fVR denotes a focal length of the negative lens group in the third lens group.
Dependencies are inferred from the claim text.