Optical system, optical apparatus equipped therewith, and method for manufacturing optical system
AssigneeNikon Corporation
InventorsHiroki Harada, Issei Tanaka
Life of this patent
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Abstract
An optical system SL installed in a single-lens reflex camera includes, in order from an object side, a first lens group G1, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The second lens group G2 is disposed movably in a direction including a component perpendicular to an optical axis, and a given conditional expression is satisfied, thereby providing an optical system having excellent optical performance with excellent vibration reduction performance, an optical apparatus equipped with the optical system, and a method for manufacturing the optical system.
Claims27
An image-forming lens comprising, in order from an object side:
- a first lens group;
- a second lens group having negative refractive power;
- and
- a third lens group having positive refractive power,
- the second lens group being disposed movably in a direction including a component perpendicular to an optical axis,
- a most object side lens in the first lens group being a negative meniscus lens having a convex surface facing the object side, and
- the following conditional expressions being satisfied:
- 0.30<f/f23<0.72
- −0.4<f/f1<0.30
- where f denotes a focal length of the image-forming lens upon focusing on an infinitely distant object, f1 denotes a focal length of the first lens group, and f23 denotes a combined focal length of the second lens group and the third lens group upon focusing on an infinitely distant object.
A method for manufacturing an image-forming lens including, in order from an object side, a first lens group, 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 such that a most object side lens therein is a negative meniscus lens having a convex surface facing the object side,
- disposing the second lens group movably in a direction including a component perpendicular to an optical axis;
- and
- disposing each lens group with satisfying the following conditional expressions:
- 0.30<f/f23<0.72
- −0.4<f/f1<0.30
- where f denotes a focal length of the whole of the image-forming lens upon focusing on an infinitely distant object, f1 denotes a focal length of the first lens group, and f23 denotes a combined focal length of the second lens group and the third lens group upon focusing on an infinitely distant object.
Dependencies are inferred from the claim text.