Variable power optical system, optical apparatus and manufacturing method for variable power optical system
AssigneeNikon Corporation
InventorsAtsushi Shibayama, Kosuke Machida
Life of this patent
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Abstract
Provided is a variable power optical system (ZL) used for an optical apparatus such as a camera (1). The variable power optical system (ZL) includes, 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 negative refractive power; a fourth lens group having positive refractive power; and a fifth lens group. Upon zooming from a wide-angle end state to a telephoto end state, a distance between each of the lens groups changes, and upon focusing from an object at infinity to an object at a close distance, the third lens group moves in the optical axis direction.
Claims18
A variable power 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 negative refractive power;
- a fourth lens group having positive refractive power;
- and
- a fifth lens group,
- upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changing, a distance between the second lens group and the third lens group changing, a distance between the third lens group and the fourth lens group changing, and a distance between the fourth lens group and the fifth lens group changing,
- the first lens group consisting of a cemented lens and a single lens arranged in order from the object, and
- the following conditional expression being satisfied:
- 3.80<f1/fw≤4.325
- where
- f1:
- focal length of the first lens group
- fw:
- focal length of the variable power optical system in the wide-angle end state.
A variable power 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 negative refractive power;
- a fourth lens group having positive refractive power;
- and
- a fifth lens group,
- upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changing, a distance between the second lens group and the third lens group changing, a distance between the third lens group and the fourth lens group changing, and a distance between the fourth lens group and the fifth lens group changing,
- the first lens group consisting of a cemented lens and a single lens arranged in order from the object,
- the fourth lens group comprising six lenses, and
- the following conditional expression being satisfied:
- 0.72<f4/f5<1.45
- where
- f4:
- focal length of the fourth lens group
- f5:
- focal length of the fifth lens group.
A method for manufacturing a variable power optical system including, 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 negative refractive power;
- a fourth lens group having positive refractive power;
- and
- a fifth lens group,
- the method comprising:
- disposing each lens group so that, upon zooming from a wide-angle end state to a telephoto end state, 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, a distance between the third lens group and the fourth lens group changes, and a distance between the fourth lens group and the fifth lens group changes;
- and
- configured the first lens group to consist of a cemented lens and a single lens arranged in order from the object,
- the method further comprising at least one of the following features (A) and (B):
- (A) satisfying the following conditional expression:
- 3.80<f1/fw≤4.325
- where
- f1:
- focal length of the first lens group
- fw:
- focal length of the variable power optical system in the wide-angle end state;
- (B) configuring the fourth lens group to comprise six lenses, and satisfying the following conditional expression:
- 0.72<f4/f5<1.45
- where
- f4:
- focal length of the fourth lens group
- f5:
- focal length of the fifth lens group.
Dependencies are inferred from the claim text.