Variable power optical system, optical apparatus, and method for producing variable power 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, and a rear lens group;

• upon varying a magnification, each distance between the neighboring lens groups being varied;
• the rear lens group comprising a focusing lens group which is moved upon carrying out focusing;
• the third lens group comprising, at a most object side, a single lens having positive refractive power;
• and
• the following conditional expressions being satisfied:
• 2.00<f1/(−f2)<3.80
• 0.15<(−f2)/|fZ|<1.00
• 0.50<f3/(−f2)<3.00 (5)
• where f1 denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, fZ denotes a focal length of a lens group located at a most image side in the rear lens group, and f3 denotes a focal length of the third lens group.

A method for manufacturing a variable magnification optical system which comprises, 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, and a rear lens group;

• the method comprising one of the following Steps A and B:
• the Step A including:
• constructing such that, upon varying a magnification, the first lens group is fixed with respect to an image plane, and each distance between the neighboring lens groups is varied;
• constructing such that the rear lens group comprises a focusing lens group which is moved upon carrying out focusing;
• constructing such that the third lens group comprises, at a most object side, a single lens having positive refractive power;
• and
• constructing such that the following conditional expressions are satisfied:
• 2.00<f1/(−f2)<3.80
• 0.15<(−f2)/|fZ|<2.00
• 1.00<f1/fw<3.00
• where f1 denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, fZ denotes a focal length of a lens group located at a most image side in the rear lens group, and fw denotes a focal length of the variable magnification optical system in a wide angle end state;
• the Step B including:
• constructing such that, upon varying a magnification, each distance between the neighboring lens groups is varied;
• constructing such that the rear lens group comprises a focusing lens group which is moved upon carrying out focusing;
• constructing such that the third lens group comprises, at a most object side, a single lens having positive refractive power;
• and
• constructing such that the following conditional expressions are satisfied:
• 2.00<f1/(−f2)<3.80
• 0.15<(−f2)/|fZ|<1.00
• 0.50<f3/(−f2)<3.00
• where f1 denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, fZ denotes a focal length of a lens group located at a most image side in the rear lens group, and f3 denotes a focal length of the third lens group.