Variable magnification optical system, optical device, and method for manufacturing variable magnification optical system

A variable magnification optical system 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;
• upon varying a magnification, distances between the neighboring respective lens groups being varied;
• and
• the following conditional expressions being 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.

A variable magnification optical system 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;
• upon varying a magnification, distances between the neighboring respective lens groups being varied;
• and
• the following conditional expressions being 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.

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.