Some people use an enlarger with the lens set to F/32. You have to do testing to determine the height of the enlarger and how much time. After development you should have a very faint gray tone, below paper white.

Some people pre-flash paper negatives in-camera with glass lenses, not pinhole, by putting a diffuser over the lens an exposure time based on a meter reading of the scene. A diffuser disc in place of the pinhole might work for the 3-chamber camera, though because of the wide angle of view, the edges would get less pre-flash intensity than the center.

That would work, but you'd ideally need a front-surfaced mirror, one devoid of scratches. There's also the "pin speck" camera concept. I've built two prototypes, but they're difficult to get to work. The idea is a front-surfaced mirror the size of a pinhole, that bounces the image to the film plane. But the difficulty is in keeping stray light from fogging the film, since the tiny mirror needs to be open to both the scene and the film plane. Both versions I made used two "feed horns," the tips connected and angled at 90 degrees to each other. The mirror was in the little box at the tips of the feed horns. Light, say from the left, would pass down the one feed horn, then bounce 90 degrees off the mirror into the other feed horn, at the end being the film plane. I don't think it's possible to have a wide angle camera with the pin speck concept, due to the problem of fogging. So narrow angles of view only. But unreversed images for direct positive paper.

The paper stays in place due to the curve of the pipe and stiffness of the paper.

In this video I wasn’t doing the reversal process, but instead using Harman Direct Positive Paper that reverses into a positive with normal B/W chemistry. The paper isn’t multi grade so you can’t control contrast with color filters. The best way to control contrast with this paper is to control the lifting on the subject. If you try to reduce development, or use a more dilute developer, it’s too easy to get poor shadows or even the reversing action won’t happen at all.

@@Joe_VanCleave thanks. I asked because of the number of videos you've done with this paper, not particularly this vide. I did see a video last night where a yellow filter got good tonal results but not sure why tbh. Anyway back to toning I just vaguely remember bleaching back images as part of the process. So thinking if the image was too dark and contrast you could bleach back to what you want tone wise? Maybe not because of the inversion.

@@Joe_VanCleave if KZfaq isn't deleting my posts again the yellow filter vid is here see from 14 mins. Black and White Paper Reversal - getting some nice results now!

@@killpop8255 Most people who work with paper use multi grade, whose high contrast part of the emulsion is activated by the blue and UV in daylight, hence why yellow filters are often used to control excess contrast. I’m using fixed grade 2 paper which doesn’t need filtering and therefore is faster than filtering MG paper with a yellow filter. As for toning, I haven’t done so in the reversal process, but this means there’s plenty of opportunity for experimenters to tinker with it.

@@Joe_VanCleave I don't have a darkroom to tinker but I can get a very small blacked out area just for dev, stop, fix single sheets of 54. Just wondering if I can err one side of good exposure / contrast. I got the paper today. "Only" need all the rest!