[polyglot]

Polyglot, I personally think that the cost/benefit comparison to roll film is a false economy for at least some of us.

One of the biggest problems I have is not finishing a roll when I shoot.

I'm to a point where when I see a shot that I want, 2-4 frames are normally more than plenty for a given subject. I roll 20-shot rolls for 35mm to minimize this, but I am finding that getting even 10 shots in a row, with the old RB, is becoming a real streatch most of the time.

If that's how you work, I can't sit here and tell you you're wrong. However, my approach is that I have four backs for my RZ and keep each loaded with a different type of film. And if I don't finish a roll, it can sit there happily until I need that film type in another week or four, at which point it'll be finished off and I don't waste any. I can put up with waiting to get my images, in fact I often have a little backlog of 5 to 15 rolls before I fire up the Jobo.

I'm not sure if it makes sense to talk about "stop[s] of detail", because the way we view images is so nonlinear. As far as information in the frame goes, the difference isn't enormous---a factor of 3 between 6x7 and 4x5, given equal film resolution---but clearly a lot of people find the visual impact of that modest difference to be disproportionate, perhaps because it crosses some critical perceptual threshold for them.

In any case, I think "detail per frame" is more important than "detail per unit area" in practice (I think that's what you're comparing above; Acros apparently costs twice as much per unit area in 4x5 as in MF, right?). One of the points of shooting large format is precisely to enlarge less, i.e., to put more film area in the image; of course that costs more per frame, and of course it doesn't make the underlying resolution of the film any higher, but it does deliver more film resolution to the viewer.

In short: It's not that you double your cost (per unit area) to keep the same resolution, it's that you sextuple your cost to triple your resolution. Diminishing returns to be sure, but somewhat offset if, like many of us, you get a higher fraction of keepers in LF.

I was referring to detail and cost per frame (35-50c vs $1.80, for first-rate films), not per area so I think we mostly agree here. I have a pair of 16x20" prints on my cubicle wall: one from 6x7 TMY2 and one from 4x5 Fomapan (Arista) 100... they have the same level of perceptible detail and the better film in smaller format gives about 4 stops of speed advantage. So even though a large negative is nice, my subjective experience is that it makes no (when using cheaper films) to visible-but-not-earthshattering (using identical films at 5x $/frame) difference in final appearance. I'd much prefer to shoot 5x7 but I can't really get the films I want in that size and my enlarger is only 4x5. The extra area would probably make more difference if I could print at 32" or 40" but I can't as yet.

Maybe I'm an incompetent, but my keeper ratio for LF and MF is about the same unless I'm doing higher-risk (uncontrolled subject) shots like candid portraits that have an inherently lower keeper rate due to fleeting expressions, etc.