Patent ID: 11899189
Assignee: NIKON CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G  H

Claim 22:
23. A method for manufacturing one of the variable magnification optical systems A and B:
the optical system A comprising, in order from an object side: a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group, and a fifth lens group;
the optical system B comprising, in order from an object side: a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power;
the method for manufacturing the optical system A comprising steps of:
constructing such that, upon varying a magnification, distances between the neighboring respective lens groups are varied; and
constructing such that one of the following features X and Y is satisfied:
the feature X comprising:
constructing such that the following conditional expressions are satisfied:

1.00<f3/(−f2)≤2.10

1.00<f1/(−f5)<2.50

where f3 denotes a focal length of the third lens group, f2 denotes a focal length of the second lens group, f1 denotes a focal length of the first lens group, and f5 denotes a focal length of the fifth lens group; and
the feature Y comprising:
constructing such that the following conditional expressions are satisfied:

2.60<f1/(−f2)<4.50

1.00<f3/(−f2)≤2.10

where f1 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; and
the method for manufacturing the optical system B comprising steps of:
constructing such that, upon varying a magnification, distances between the neighboring respective lens groups are varied; and
constructing such that the following conditional expressions are satisfied:

0.64<f4/(−f2)<2.20

1.00<f3/(−f2)<3.00

where f4 denotes a focal length of the fourth lens group, f2 denotes a focal length of the second lens group, and f3 denotes a focal length of the third lens group.