Zoom optical system, optical apparatus and method for manufacturing the zoom optical system
AssigneeNikon Corporation
InventorKosuke Machida
Life of this patent
Estimating the term…
Abstract
A zoom optical system (ZL) comprises, in order from an object, a first lens group (G1) having a positive refractive power, a second lens group (G2) having a negative refractive power, a third lens group (G3) having a positive refractive power, a fourth lens group (G4) having a positive refractive power and a succeeding lens group (GR). In the zoom optical system, upon zooming, distances between adjacent lens groups change, and the succeeding lens group (GR) includes a plurality of focusing lens groups that have positive refractive powers and move upon focusing.
Claims26
A zoom optical system, comprising, in order from an object:
- a first lens group having a positive refractive power;
- a second lens group having a negative refractive power;
- a third lens group having a positive refractive power;
- a fourth lens group having a positive refractive power;
- and a succeeding lens group, wherein
- upon zooming, distances between adjacent lens groups change, and
- the succeeding lens group includes a plurality of focusing lens groups that have positive refractive powers and move upon focusing.
A zoom optical system, comprising, in order from an object:
- a first lens group having a positive refractive power;
- a second lens group having a negative refractive power;
- a third lens group having a positive refractive power;
- a fourth lens group having a positive refractive power;
- and a succeeding lens group, wherein
- upon zooming, distances between adjacent lens groups change,
- the succeeding lens group includes, in order from the object, a first focusing lens group that has a positive refractive power and moves upon focusing;
- and a second focusing lens group that has a positive refractive power and moves upon focusing, and
- satisfies the following conditional expressions:
- 0.20<fF1/fF2<3.00
- 0.10<BFw/fw<1.00
- where fF1:
- a focal length of the first focusing lens group,
- fF2:
- a focal length of the second focusing lens group,
- BFw:
- a back focus of the zoom optical system in a wide-angle end state, and
- fw:
- a focal length of the zoom optical system in the wide-angle end state.
A method for manufacturing a zoom optical system, comprising:
- arranging in a lens barrel, in order from the object:
- a first lens group having a positive refractive power;
- a second lens group having a negative refractive power;
- a third lens group having a positive refractive power;
- a fourth lens group having a positive refractive power;
- and a succeeding lens group,
- the arranging being such that upon zooming, distances between adjacent lens groups change, and
- further comprising at least one of the following features (A) or (B):
- (A) the succeeding lens group includes a plurality of focusing lens groups that have positive refractive powers and move upon focusing,
- (B) the succeeding lens group includes, in order from the object, a first focusing lens group that has a positive refractive power and moves upon focusing;
- and a second focusing lens group that has a positive refractive power and moves upon focusing, and
- satisfies the following conditional expressions:
- 0.20<fF1/fF2<3.00
- 0.10<BFw/fw<1.00
- where fF1:
- a focal length of the first focusing lens group,
- fF2:
- a focal length of the second focusing lens group,
- BFw:
- a back focus of the zoom optical system in a wide-angle end state, and
- fw:
- a focal length of the zoom optical system in the wide-angle end state.
Dependencies are inferred from the claim text.