Thanks, but that's not my picture. It's from the Bradley mine slide show and was taken by Miner Mike. All I did was desaturate it and add several platinum filters to it to mimic the true platinum proccess. I think it came close, but it's not nearly as rich as Horgan's print. I would assume, if he was working in the 1920's, that he used electric flashbulbs along with some kind of a press or view camera. I seriously doubt that magnesium flashpowder would have been used, since it was becoming obsolete at the time. The explosive atmosphere of a working coal mine would also have to be taken into conideration.
The prevailing methods for lighting large interiors at that time
were painting with light and multiple flash. These are the same methods used today. I think that there is an unfair tendency these days to assume that photography was much more primitive back then. In truth, the basics of photography have not changed very much since the 1880s. Sure, new technology has been developed both in chemistry and computers, but the properties of light, and methods used to record it, remain constant.
Here is a photographer's description of a platinum print vs. a regular silver print:
Quote:
I recently attended the Alternative Process International Symposium in Santa Fe, where I saw a step test printed on both silver-based paper and platinum-coated paper. The comparison was remarkable--the platinum print had easily three stops more tonal range clearly delineated. Platinum is much more permanent than silver. Its only drawback is its slow speed, which allows only for contact printing.