I'm a little ashamed to ask this question. But i have a Brinca Sq-a loaded with Ilford fp4 @ 125iso. The Sq-a 120mm back has 1/3 increment markings between the 100 and 200 iso speed settings. Should a 125 iso film as i'm using just be set to the first increment past 100? Sry about this terrible question btw! Stephen.