Hi Bro...
You can set to choose 1/2 stops or 1/3 stops by using one of the other side of the EV knob.....
If you set to use 1/2 stops on the EV knob....it will reflect 1/2 stop shifts in Aperture settings.
If you use 1/3 stops on the EV knob...it will eflect 1/3 shift in aperture Settings....