I had the same question some time back & went to Agfa tech guys & asked. They say 10ml of rodinal syrup per 8x10 film unit or equivalent no matter the dilution. I know a number of people say you can use less & they do so successfully. Agfa may be overly cautious but no one has problems when using more than the minimum needed, just when they try skimping on the threshold amount.(posted 8262 days ago)