following the advice of experts here on this forum, I have found good working parameters for developing Delta films. I am trying to understand the rationale behind dilution of developers. why diluting XTOL 1:2 and greater is preferred for highter EI ranges? why is this? the increase in development times are not linear, so is it all empirically derived or are the adjustments calculable?(posted 9086 days ago)finding something that works at EI1600 (Xtol 1:1 15'@75degrees), leaves me guessing for both EI3200 and launch times for Delta 400. suggestions?