Ambrotype of a war veteran and his wife. He's wearing a British Crimean War medal with bars. 1860s

Interestingly enough, Time is the only variable in quantum physics describing physical phenomena that you can make negative without getting a garbage answer. (please see yesterday’s post about the film Primer, the Wiki page linked therein will be of interest)

Exposure times on an Ambrotype were 5-60 seconds or longer, depending on the available light.

I always remember being told “they’re not smiling because they had to sit there for 30 minutes to take a picture,” but that doesn’t quite seem to be the case (and I was told this about my great- and great-great-grandparents’ portraits). There’s almost no way a person can sit still for that long and still be in focus, just due to the small muscle shifts and breathing and what-not. I’m guessing some still-life photography may have been done that long, and, well, you know how rumors run.

Anecdotes (or as my fiancée tries to make them, “antidotes”) aside, this trip down wikipedia lane has me wondering, and this question might get all my photographique friends hot, could you reproduce this photographic technique at home with the right materials, and then use a projector to expose the plates, effectively turning any picture you might take into an ambrotype plate? Sony does make some high-end 4k projectors (I don’t mean 4096 pixels, I mean 4096 x 4096 pixels) so your 16 or less megapixel image could be represented in toto (well, assuming the image could be projected in-focus on a small enough area to match the size of the ambrotype plate – could probably just hack in a lens to focus at that length).