Seeking recent thread about making color photos from black and white film

[Blackmarxz]

Hello, as per title trying to find a recent thread (in last few months)nuthatch talked about making color photos from black and white film. Process along lines of using three different filters and assigning to channels in photoshop..... sorry I can’t see it in search.... cheers

[Bob Salomon]

You need 3 color separation filters, red, blue and green. You take 3 shots. One with each filter. Then you can project them through 3 projectors, each with the same filter on them. Or make a print with 3 exposures. Each with the proper filter.

[ic-racer]

I don't understand what "assigning to channels in photoshop" means, but if you are working in the digital domain, couldn't you use a sensor with full color capability from the start?

[Mark Stahlke]

I scraped these instructions from a LFPF post years ago. I have the filters but have never tried the technique. I wish I knew who should get the credit for it.

This information is something of a repeat of some messages I posted a few years ago.

From the turn of the century until the early 1950s one-shot color cameras were manufactured that made three exposures at one time, one through the Red filter, the other through a Green filter, and a third through a Blue filter. This was achieved by means of pellicle beam splitters that transmitted a part of the light but reflected the other part. Before that cameras with sliding backs were used without the pellicle beam splitters.

It is very feasible to make color separations with B&W film, making exposures on three different sheets of filmn with a view camera. For in-camera separations the recommended filter set is 25 Red, 58 Green and 47 Blue. You mark the film holders as R, G or B, and before developing clip the R on one corner, the Green on two corners and leave the B as is. This helps to identify them later. You can combine the separation negative files, after scanning the negative, to combine the spectrum for a full color shot. If you use an Apo lens and choose stationary subjects the quality can be quite high, at least as good as with transparency film of the same size.


The best film for color separations is one that has a short toe and shoulder and a very long straight line. Both Tmax-100 and TMY work quite well. For best results you will need to expose and develop the three records individually, but if you have the luxury of curve correction in Photoshop just give +3 stops exposure for the Red and Green filters, and +2 stops for the Blue filter. Develop the Red and Green negatives for the same time, the Blue for about 50% more.

There may be faster ways of doing this but this is how I merge the separation layers in Photoshop.

1. Name the scanned files by the taking filter, Red Negative, Green Negative and Blue Negative.
2. Choose File>Scrips>Load Files into Stack. Check auto align box.
3. Convert the separation files to their respective subtractive colors. Change the Red negative file to cyan, the Green negative file to magenta, and the Blue negative file to yellow.
A. Convert the files to their color.
B. First, select the Red negative file. Then go to Windows>Swatches and put the eyedropper tool over the CMYK Cyan patch, located in the upper left area. Click on the CMYK Cyan patch and the foreground color will change to Cyan. Now go to Edit>Fill and make sure Foreground Color is selected and that Blending Mode is set to screen.
C. Repeat for the Green negative file, choosing CMYK Magenta with the eyedropper tool to set the foreground color.
D. Repeat for the Blue negative file, choosing CMYK Yellow with the eyedropper tool to set the foreground color.
4. Combine the three separate images to form a full color image.

A. Create a new file, File>New. This file should be at least as large as the largest of the three separation layers. Set Mode to RGB and set background to White.
B. Copy the first layer to the new file. In the old file make the Red/Cyan layer the active layer, choose Select>All, then Edit>Copy Merged. Now go to the new file and do Edit>Paste.
C. Repeat for the Green/Magenta layer and for the Blue/Yellow layer.
D. When finished the Blue/Yellow layer should be on top. Make this layer active in the Layers Palette and change the blending mode to Multiply.
E. Repeat this step for the Green/Magenta layer.
F. Leave the blending mode set to Normal for the Red/Cyan layer
G. Your image should now be in color. Save the file.

[Peter Mounier]

Here are a couple of threads on the subject.
https://www.largeformatphotography.i...eparations-HOW
https://www.largeformatphotography.i...hic-or-similar

[Blackmarxz]

I don't understand what "assigning to channels in photoshop" means, but if you are working in the digital domain, couldn't you use a sensor with full color capability from the start?

Well it was more for a particular effect that happens when parts of the image moves..... cheers

[Blackmarxz]

Here are a couple of threads on the subject.
https://www.largeformatphotography.i...eparations-HOW
https://www.largeformatphotography.i...hic-or-similar

Great - thanks very much

[Blackmarxz]

I scraped these instructions from a LFPF post years ago. I have the filters but have never tried the technique. I wish I knew who should get the credit for it.

Awesome - much appreciated !

[Drew Wiley]

Tricolor photography has been around as long as panchromatic film - over 100 years in some form or another. It's takes some testing to properly balance the exposures.
You want a matched filter set, the most accurate being 61 green, 29 red, and 47B blue. But due to such long exposures for the former, people often substitute 25 red, 58 green, and 47 Blue. I personally find 61, 29, and 47 an excellent set for TMX100 per se. And I do recommend this film in particular because, if you have equal exposure densities, you can develop all three sheets together for the same amount of time and get a matched set. With TMY or FP4, different filters require different dev times. HC-110 is a good developer. But you really do want to do your homework up front and obtain fully overlapping densitometer curves. This will save a lot of putzing around afterward trying to reconfigure inadequate curves. You also need to keep your film as flat as possible; I use adhesive holders.

[sanking]

I attached those instructions to a message to the LF forum back in May of 2009.
https://www.largeformatphotography.i...ite-film/page4

However, the attachment does not appear in my current link to the thread. Or it may have been in another thread?

Sandy

This information is something of a repeat of some messages I posted a few years ago.

From the turn of the century until the early 1950s one-shot color cameras were manufactured that made three exposures at one time, one through the Red filter, the other through a Green filter, and a third through a Blue filter. This was achieved by means of pellicle beam splitters that transmitted a part of the light but reflected the other part. Before that cameras with sliding backs were used without the pellicle beam splitters.

It is very feasible to make color separations with B&W film, making exposures on three different sheets of filmn with a view camera. For in-camera separations the recommended filter set is 25 Red, 58 Green and 47 Blue. You mark the film holders as R, G or B, and before developing clip the R on one corner, the Green on two corners and leave the B as is. This helps to identify them later. You can combine the separation negative files, after scanning the negative, to combine the spectrum for a full color shot. If you use an Apo lens and choose stationary subjects the quality can be quite high, at least as good as with transparency film of the same size.


The best film for color separations is one that has a short toe and shoulder and a very long straight line. Both Tmax-100 and TMY work quite well. For best results you will need to expose and develop the three records individually, but if you have the luxury of curve correction in Photoshop just give +3 stops exposure for the Red and Green filters, and +2 stops for the Blue filter. Develop the Red and Green negatives for the same time, the Blue for about 50% more.

There may be faster ways of doing this but this is how I merge the separation layers in Photoshop.

1. Name the scanned files by the taking filter, Red Negative, Green Negative and Blue Negative.
2. Choose File>Scrips>Load Files into Stack. Check auto align box.
3. Convert the separation files to their respective subtractive colors. Change the Red negative file to cyan, the Green negative file to magenta, and the Blue negative file to yellow.
A. Convert the files to their color.
B. First, select the Red negative file. Then go to Windows>Swatches and put the eyedropper tool over the CMYK Cyan patch, located in the upper left area. Click on the CMYK Cyan patch and the foreground color will change to Cyan. Now go to Edit>Fill and make sure Foreground Color is selected and that Blending Mode is set to screen.
C. Repeat for the Green negative file, choosing CMYK Magenta with the eyedropper tool to set the foreground color.
D. Repeat for the Blue negative file, choosing CMYK Yellow with the eyedropper tool to set the foreground color.
4. Combine the three separate images to form a full color image.

A. Create a new file, File>New. This file should be at least as large as the largest of the three separation layers. Set Mode to RGB and set background to White.
B. Copy the first layer to the new file. In the old file make the Red/Cyan layer the active layer, choose Select>All, then Edit>Copy Merged. Now go to the new file and do Edit>Paste.
C. Repeat for the Green/Magenta layer and for the Blue/Yellow layer.
D. When finished the Blue/Yellow layer should be on top. Make this layer active in the Layers Palette and change the blending mode to Multiply.
E. Repeat this step for the Green/Magenta layer.
F. Leave the blending mode set to Normal for the Red/Cyan layer
G. Your image should now be in color. Save the file.