Zoom lens and imaging apparatus

A zoom lens substantially consisting of:

• a first lens group having a positive refractive power, which is fixed while changing magnification;
• a second lens group having a negative refractive power and a magnification change function, which moves while changing magnification;
• a third lens group having a positive refractive power, which moves while changing magnification and corrects variations in an imaging plane due to changes in magnification;
• and
• a fourth lens group having a positive refractive power and an image formation action, which is fixed while changing magnification and in which a stop is disposed on the most-object side, in this order from the object side;
• wherein
• image formation magnification rates of the second lens group and the third lens group simultaneously pass a −1× point when changing magnification from the wide angle end to the telephoto end;
• the second lens group substantially consists of a second-a lens group having a negative refractive power and a second-b lens group having a positive refractive power in this order from the object side, the second-a lens group and the second-b lens group independently moving while changing magnification from the wide angle end to the telephoto end;
• and
• the third lens group substantially consists of a third-a lens group having a positive refractive power and a third-b lens group having a positive refractive power in this order from the object side, the third-a lens group and the third-b lens group independently moving while changing magnification from the wide angle end to the telephoto end.