Still on my quest for an ISO 100 film that can actually be shot at EI 100 and still get zone I at 0.1 over b+f, the next try is Fuji Acros (only because I happen to have a roll in the fridge!). My trials with Tmax using HC-110, Rodinal and Microphen resulted in speeds between about 32 and 80!(posted 8264 days ago)Anyone tried Acros in Microphen and if so, what EI, developer, time and temperature did you use? It's not listed in the good old "massive development chart" and a web search didn't turn anything up either. I doubt it will reach 100 speed even in microphen, but since I have it on hand, it's worth a test.
The second part of my question is why ISO ratings are so inflated? I thought that the ISO standard was based on 0.1 above b+f when the film is developed to some standard CI value. I doubt I could get true 100 speed out of most ISO 100 films if I left them in Microphen all day and developed to a CI of 1.0. My consistant experience has been that any film I test is actually rated about 1/2 what's on the box with any sort of "normal" development. How do the film companies manage to come up with such inflated ISO numbers, or is the ISO number not based on 0.1 above b+f to determin the speed point?