100 year old color photography...

With exposures of 6 seconds, the effective ASA/ISO speed at that time had to be fractional.
 
dmr, no doubt the emulsion speed was low but the plates had little sensitivity through the cyan filter and even less through the magenta and yellow. Also, fairly small apertures would be needed on the lenses to get three reasonably in-focus images with a poorly color corrected set of lenses.
 
Al Kaplan said:
dmr, no doubt the emulsion speed was low but the plates had little sensitivity through the cyan filter and even less through the magenta and yellow. Also, fairly small apertures would be needed on the lenses to get three reasonably in-focus images with a poorly color corrected set of lenses.
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things were a lot harder when we were lads Al!:p
 
ome almost look like a mild HDR type of shooting with a vast tonal range.
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The Prokudin-Gorsky photos were preserved as black and white negative records of the colour primaries. Unchanging and without colour- the colour that we see now is really a digital interpretation of the data preserved by the black and white records. A great deal of digital intercession went into the regeneration of the photos' hues, hence the "HDR" look. A similar reproduction from earlier pre-digital times would have produced a different palette, such as those seen in Jack Cootes "The Illustrated History of Colour Photography".

With exposures of 6 seconds, the effective ASA/ISO speed at that time had to be fractional.
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According to the book quoted above, Prokudin-Gorsky used three types of plates. The red records used "high speed" Ilford Panchromatic plates. But the 1908 description of 'high speed' would be different from now. The 6 seconds may mean the total combined exposure through each of the colour filter. Each primary colour exposure was made one at a time, through the same lens, using a sliding back for three plates. Some of the photos with moving subjects would show fringing.

through the cyan filter and even less through the magenta and yellow.
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Actually, those would be Blue, Red, and Green separation filters. Each filter would allow just 1/3 of the visible spectrum, so light loss was really great.
 
Trichromic one shot cameras were popular until the first slides appear during the thirties.

At the time you could make color pictures with this process by printing on carbon teinted emulsion. (BTW currently available here :http://www.colorcarbonprint.com)

I am currently restoring a bunch of trichromic one shot cameras for a Trichrom specialist, Henry Gaud, see his blog (in french, unfortunately) :

http://trichromie.free.fr/trichromie

The biggest is a 5X7inch camera with 3 plate holder. I have another under repair that is a 4X5 inch, imagine a supersized Speed graphic with 3 sheet film holder...

A 2X3 one shot tri-color Devin camera :

devin.jpg
 
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