To test a film with my 4x5 I load all the holders with my standard film on one side and the film to be tested on the other. This makes it easy to make identical shots in the field; all I have to do is adjust for the speed difference.

Then I proof them together, and tweak the speed rating/ dev time of the new film to try and match the speed and contrast of the standard.

This has worked to some extent; but I'm finding that to really see the differences between films, they have to be printed to final size. Proofs don't really cut it. I guess my dad was right - there are no shortcuts.

For me the really hard part is deciding what's better. There's so many variables. Chasing them all down would become a career in itself. I've been testing BFP in PMK next to TX in HC110 for eight months now and, although I'm tired of running two separate processes, I can't decide which I like better enough to settle on for a while. Now I'm finally on my last box of the old TX, have a few hundred sheets of the new TX on hand...oh bother. I'd rather be photographing.