Hello Kerik,
Thanks for your reply, you are right about my obssessing, but it's a my habit to try to find out all the informations that I can find and try to understand them, and also in this case, I usually do my sensibilizer at 27% but I never have done my PT or PD solutions(I'll try to do them early) and my BS solutions are 20% and 15%, is these difference with Jeffrey's calulator(little) that I would like to understand (it's a little difference of chemical amount)why, and in what way pictures would change.
Best
CIAO
Stefano