I found something in cleaning today that I forgot I had. It's the only one I've ever seen, and I thought I'd see if anyone else here knew anything about it. It is an 8x10 film holder, or so it looks from the outside. Pull the slide, though, and you see more wood and a couple smaller frames, the smallest having a metal septum to hold a sheet of 4x5 film. It looks like it could be configured to hold a sheet of 5x7 film as well. It's like this on both sides. It is marked "EASTMAN KODAK CO. F.&S. DEPT" on one side and "8X10 EASTMAN PLATE PAT. OCT. 9. 1923" on the other. Does anyone have any info on these? It's interesting, though I'm not sure I'd ever actually use it. An alternative of sorts to a reducing back, I suppose, though less practical I would say. Thoughts?