Specifically, a 6×9 cm Lumière orthochromatic (not sensitive to red light) dry plate from god knows when. Early 20th century, after 1911. Pour la PORTRAIT it said, so la portrait I made.
Exposure time 10 seconds, at f/4.5, treating the plate as ISO …stupidly low (technical term). ISO 1 or so. It was probably faster when it was new, but it’s quite foggy now, roughly 100 years after it’s use-by date.
I think this is also underdeveloped, but I had two earlier tries, and with those the emulsion sort of bubbled up and detached from the glass (even more than it does on this one). That may be the developer I used (Rodinal) or the fixer or it may be any number of other things – including the fact that I’m using these a century too late, I guess. Anyway, for this one I tried to keep the time in the developer as short as possible, and it’s also probably not fixed quite long enough. That seemed to have helped a little bit but it’s still not ideal.
How these plates survived from 1910/1920s(30s? je ne sais pas) France to 2020s Berlin unopened is a bit of a miracle anyway. There’s maybe an argument to be made that they should be preserved unopened. But I don’t agree with that, obviously. These were made to be used, and they’re also are not that rare. Or not that expensive in any case, I paid 20€ for 12 plates.
(Lumière is significant in that they invented color photography, among many many other things.)
The camera is a no-name German 9×12 thingy from …yeah from around 1920 or so. I used an adapter for 6×9 plates.
All that said, it’s pretty amazing this stuff still works and makes pictures. And quite easily at that. If you can sit still for 10 seconds.