as long as your non-defined blacks are below your black point and your non-defined whites are above you your white point, you can place your 18% or 9% or 72% any where you want; regardless of asa or EV.
For example, i'm shooting btzs and running at ev. so for positioning i can place my 72% or 4.5% or whatever wherever i want as long as i consider base black-point and white-point, easy peasy! but it's a sliding scale based on iso you say, so, i just jack the meter or my brain to compensate. it's still the same set of numbers, just slid up or down a bit twixt the ev scale, time and temp and stars being constant...
or is the fermented hops and barley working against me?
when i say "it doesnt even matter" im talking iso and keeping whatever ratios and meaning positioning relative to, of course.