Seems to me the pinhole will project a pinhole image of the light source on to the film. That would be bad...Originally Posted by jdef
Solution: use a diffuser between light source and pinhole, evenly illuminated by the light source (you can check with a light meter, with the filter removed from the safelight), large enough that the image of the diffuser will cover the entire film. Build this all into a black foam core box and you have a latensification unit that could potentially be operated (including inserting and removing film holders) in a lit room. There'll be some light lost to scattering by the diffuser, so you may need to experiment with light levels and exposure times, but that and getting a good light seal ought to be the only significant issues.
Of course, a group of pinholes would be better in terms of passing more light (assuming you're using a very dim source -- one advantage of a small, single pinhole is that you don't *need* a very dim source), as long as the diffuser is large enough so that every pinhole's image of the diffuser covers the entire film.