I am new to the ND filter game and was hoping to get some advice. I was shooting with two cameras the other day and A cam had a .6 ND filter and B cam had a tiffen 77mm variable ND. I tried to match the exposure on both cameras but had trouble reading what the variable ND markers meant.
Does anyone know the break down on how the little notches work? Is it by f-stop? Or actual .3,.6,.9 and so on?