Ed, I thought that it did not make a great difference what tone my subject is. If theory matched practice, a gray card placed at Zone I would yield a negative at 0.1 density and a white wall placed at Zone I would also yield a negative at 0.1 density. I thinking of the proverbial gray snow or black dog, white dog thought experiments.(posted 8500 days ago)In this particular case, I used a gray card, a medium blue poster board, and a dark maroon wool blanket all lighted identically. Of course only the gray card read 1/60 at f/2.8.
I don't really mind rating Tri-X at 200 since I've gotten good results so far. However, I'm anal enough to be bothered that I'm nowhere near the expected theoretical result. Is it possible that "normal" 35mm negs are really supposed to be thinner than 4x5?