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This method of printing was used in machine printers of old and does produce cleaner colors. Enlarger printing does require an enlarger that is locked down firmly (read that as braced in all key areas) and if negatives or masks are to be switched between exposures a registered carrier is a requirement. Any combination of red green and blue will "work" the sharper cut filters giving more saturated colors when compared to the broader brothers. The effects are subtle and worth seeing for one's self if one has the time.
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Would this be any different, (other than being more of a pain in the ass!) than using the Minolta/Beseler 45A color head? That had separate red, green, and blue exposures through flashtubes and filters. You can adjust, fire, and change the channels independently, in 1% increments. PLus of course a very nice color analyzer built in....
-Ed
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Additive/subtractive printing
 Originally Posted by analogsnob
This method of printing was used in machine printers of old and does produce cleaner colors. Enlarger printing does require an enlarger that is locked down firmly (read that as braced in all key areas) and if negatives or masks are to be switched between exposures a registered carrier is a requirement. Any combination of red green and blue will "work" the sharper cut filters giving more saturated colors when compared to the broader brothers. The effects are subtle and worth seeing for one's self if one has the time.
You must be referring to really old photofinishing printers, which were additive printers: successive exposures through red, green & blue filters.
The Kodak S-series printers, and most other printers I encountered in 19 years in pro and amateur labs, were subtractive printers. These made an exposure which started with white light, and any two of the cyan, magenta and yellow filters would swing into the optical path, in various combinations, and the exposure would terminate when the third filter and the capping shutter swung in, in concert.
Exposure was determined by a series of six photo tubes, with two sets covered in a filter of the three additive primary (RGB) colours. A human operator would make density offsets, and could make colour offsets, as required.
The advantage to subtractive printers is that the exposure times tended to be shorter than for additive printers. All of the three CMY filters had a certain amount of "crosstalk," which I was told was designed into the system, to make the production of photofinishing-grade prints easier. I never has the opportunity to compare a negative printed on an S-series printer, with one printed via the additive method, with one printed in a standard CMY colour head enlarger, but I have no doubt that the other contributors to this thread are correct when they say that it made for brighter colors.
I spent more time than I care to remember dealing with S-series printers, with photographic and electro-mechanical maintenance problems. I wish I had a dollar for every time I set the slope centres or firing points on a printer!
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Guys;
In the 50s there were 2 Kodak B&W printers, the model 3 and the model 4. The 3 was for small format, 35mm and 828 and smaller. The model 4 was for MF or 620, 120, 616 and etc. The Consent Decree made it mandatory for Kodak to supply a color printer for photofinishers so they produced the model 5 which worked for all formats and used 3 color exposures for printing. I never used one of these, as we only made enlargements using CC filters, but I have seen the model 5 and have heard that it was a beast and very slow.
Prints were developed on reels in 8x10 baskets in lengths of about 50 feet. Manual and Nitrogen burst agitation was used and the process took about 1 hour.
Just a bit of history. I ran that process so often that I vowed to change it if I ever worked for EK. Well, my wish came true!
PE
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I never printed with three separate exposures but I think I may try it now. I've used a Phillips PCS 150 additive (RGB) color head for over 20 years and I find it easier to dial in the color balance and maintain a balance through several prints than on a dichroic (subtractive) machine. RGB printing is particularly cool for printing transparencies on Ciba/Ilfochrome if you can afford it now-a-days.
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If anyone has the means to make two comparison prints from the same negative and post them, it would be a great resource for everyone interested. I doubt if there's such n example anywhere on the internet.
nyoung (neil young?  ), if you try it, please let us know!
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Originally Posted by holmburgers
If anyone has the means to make two comparison prints from the same negative and post them, it would be a great resource for everyone interested. I doubt if there's such n example anywhere on the internet.
nyoung (neil young? ), if you try it, please let us know!
I may have one here. If I do though, I cannot post the entire photo as I don't have rights to the model used.
PE
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No worries, something's always better than nothing.
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Is there a filter with three narrow passbands at R, G and B, that would change white light to trichromatic RGB "white"? It would give the same saturation boost by lowering crosstalk with white-light source, but with single exposure.
Another option would be to use RGB LED source, but the most common ones wouldn't probably have the best possible wavelengths so we would again have some crosstalk.
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