Quote Originally Posted by bensyverson View Post
Actually, lots of people claim to have issues with film flatness when using standard LF film holders. The theory is that while rollfilm can be stretched and pressed onto the film aperture, sheet film can "rattle around" within the guide rails.

I've never had problems with film flatness, but I shoot color film, so what do I know? I'd probably never see the difference.
I think that's a lot of nit-picking. For things where you'd want everything in focus, the lowest you'd go is f/11 while using tilts. That's still around being equivalent to f/3 for a 35mm camera. Not microscopic DOF.

From what I've read, that's more of a problem on some of the poorly made film-holders, and more-so for 8x10 where pointing down. I've held junk-film in the holder upside down and I see no noticeable bow in the film. When focusing my 90/4.5 even wide-open, I don't see real noticeable changes in DOF if I move the rail less than a mm.

I think this would matter most if you're doing very narrow DOF work with lenses wide-open, like my 135/3.5, which would be like using a 38/1 on 35mm. I'll have to see if I notice anything there with problems with DOF when doing very shallow DOF work. But even so, probably the much greater factor is going to be subject movement if it's a person.

Btw, when stopping down, beyond f/22, I think film-flatness hardly means anything at all. My first piece of film, I jammed in the same way the dark-slides go (I didn't realize it had to go the other way, behind the rails). So it was jammed in there, completely misaligned, not anywhere near standards. At with my 203/7.7 at f/45, I still got a very tack sharp exposure. That's a huge screw-up (on my part) beyond any kind of film-flatness issues you're going to see, but it still turned out ok for a large f-stop.