Patent ID: 11960065
Assignee: NIKON CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 21:
22. 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.