Variable magnification optical system and imaging apparatus

A variable magnification optical system substantially consisting of:

• a first lens group having positive refractive power, and which is fixed during magnification change;
• a second lens group having negative refractive power;
• a third lens group having negative refractive power;
• a fourth lens group having negative refractive power;
• and
• a fifth lens group having positive refractive power, and which is fixed during magnification change, which are in this order from an object side,
• wherein the second lens group, the third lens group and the fourth lens group move when magnification is changed from a wide-angle end to a telephoto end, and
• wherein the first lens group consists of a 1f-th lens group having negative refractive power, a 1m-th lens group having positive refractive power and a 1r-th lens group consisting of a 1r1-th lens having positive refractive power with a strong convex surface facing the object side, a biconvex 1r2-th lens and a convex meniscus 1r3-th lens with a convex surface facing the object side, and the 1r-th lens group having positive refractive power as a whole, which are in this order from the object side, and
• the 1f-th lens group consists of a concave meniscus lens with a convex surface facing the object side and a negative lens, which are in this order from the object side.