I initially wanted to do the test I outlined (and deleted) with a step tablet on my white and black frame-filling backgrounds - which is part 2 of my test. But the problem I keep running into is how to use my Stouffer reflection target and still get something that reproduces on the negative large enough to measure accurately with the densitometer. If I move the camera close enough to get that, I have to focus significantly closer than infinity to avoid blurring the tablet too much. But then lens extension becomes a variable. I wish I had some kind of bigger step tablet.