I think I have seen photos of a black-and-white diorama, maybe in one of the old
Military Modelling Euro Militaire specials. However, don’t ask me to find it, it would mean finding all those issues first before I can even start looking through them
The main problem, I’d say, is to make it convincing. A true black-and-white photo shows only how light or dark things are, so you will have to think a lot about the brightness of the colours of everything in the diorama, rather than about what shade they are. This is much harder than it sounds, because normally, you tend to think in terms of colour
and brightness together. This isn’t really a problem with two shades of the same colour: something that would normally be dark green, you should paint with a darker grey than something that’s light green. However, is medium blue darker or lighter than medium green, or maybe the same shade?
Another problem here is: what kind of black-and-white are you trying to replicate? Digital black-and-white photos have a very different appearance than “analog” ones, because the digital ones are made by simply discarding the colour to only leave the brightness of each pixel. Analog photos, though, don’t work like that: the chemicals used for black-and-white photography are more sensitive to certain wavelengths of light than to others, so that (for example) blue usually appears darker than red, even if the blue was actually lighter on the real thing being photographed. And then there’s different types of film that give almost the opposite result …
Compare:
(
Wikipedia)
(
Wikipedia)
On both planes, the roundel is yellow, blue, white and red from the outside in. You’d never know they were the same colours from these photos, though
That difference in how colours are registered on the film, by the way, is why most digital black-and-white photos that try to look historical, actually end up looking subtly wrong
Of course, much of this last stuff this is not necessarily a concern if you just want to build a diorama in black-and-white — just going for only shades of grey will probably look convincing enough. The main thing, like I said, will be deciding how dark or light to make everything so it appears believable.