Variable magnification optical system, optical equipment, and method for producing variable magnification optical system

A method for manufacturing a variable magnification optical system comprising, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power and a fourth lens group having positive refractive power, comprising the steps of:

• constructing such that, upon varying a magnification, a distance between the first lens group and the second lens group is varied, a distance between the second lens group and the third lens group is varied, and a distance between the third lens group and the fourth lens group is varied;
• constructing such that the first lens group consists of, in order from the object side, a negative lens and a positive lens;
• and
• constructing such that at least one of the following features (A) or (B) is provided:
• (A) the second lens group consists of, in order from the object side, a 2a lens group having positive refractive power, a 2b lens group having positive refractive power, and a 2c lens group having negative refractive power,
• (B) the following conditional expression is satisfied:
• 0.10<f11/f1<1.20
• where f11 denotes a focal length of the negative lens, and f1 denotes a focal length of the first lens group.

A variable magnification optical system comprising, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power and a fourth lens group having positive refractive power;

• upon varying a magnification, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the fourth lens group being varied;
• and
• the first lens group consisting of, in order from the object side, a negative lens and a positive lens;
• wherein the following conditional expression is satisfied:
• 0.10<f11/f1<1.20
• where f11 denotes a focal length of the negative lens, and f1 denotes a focal length of the first lens group.