5 Frames… Of trichromes with ILFORD FP4 PLUS (35mm Format / EI 125 / Canon EOS 1n + Canon EF 24mm f/2.8) – by Anthony Pearson

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When my local Max Spielmann closed for lockdown, I lost my go-to for colour film processing. I couldn’t face going cold turkey, and haven’t got the sous-vide needed for colour processing at home. I can process black and white film though. So I started making trichromes.

A trichome is a colour photograph made from three black and white photos taken using red, green and blue filters. (It’s actually taken me 15 frames to make my 5 frames.)

The black and white photos are scanned and loaded into the red, blue and green channels in a photoshop document. As if by magic, the black and white turns into colour.

You have to use a panchromatic film to make a trichrome: that’s a black and white film which is sensitive to red, blue, and green light. ILFORD FP4 PLUS works really well. Old-school, orthographic, black and white films are sensitive to blue and green light, but not red, which isn’t going to make for a full-colour trichrome.

Using well-matched red, green and blue filters helps a lot. If you use filters of different densities or slightly “off” colours you’ll spend a lot of time in Photoshop fiddling with the channels trying to get decent colours. That said, I’m not after super accurate colours. I’m after nice colours. That the process isn’t accurate is most of its charm. (See also film vs digital.)

You need a tripod, and a static subject. Unless the three photos are identical your colour photo will look like an out-of-register screen print. Sometimes that’s a good thing though. I particularly like the red and green ghosting you get on moving trees. Portraits are possible, but your subject will have to sit very still while you take pictures and swap filters. I have taken trichrome portraits indoors using a pinhole camera. It’s a rare subject that can (and will) sit still for three 5 minute exposures.

My Canon EOS 1n + Canon EF 24mm f2.8,  Anthony Pearson

The photos here were taken using a Canon EOS 1n, an EF 24mm f/2.8 and ILFORD FP4 PLUS. The film was developed in 1:25 R09 (Rodinal) for 9 mins. The negatives were scanned on a lightbox using a home-made mask and a Sony A7R2 with a Canon FD 50mm f/3.5 macro lens. A Mac, Lightroom and Photoshop were used to create the trichromes.

My process is:

  1. Scan each set of negatives in red, green, blue order (you need to keep track)
  2. Load the scans into lightroom
  3. Open them in photoshop
  4. Convert each into a positive
  5. Copy the ‘red’ image into the red channel of the ‘blue’ doc
  6. Copy the ‘green’ image into the green channel of the ‘blue doc’
  7. Align the channels in the blue doc (which is now your trichrome)
  8. Fix the levels, flatten the image, and save the blue doc
  9. Back in Lightroom, crop the image and apply any other adjustments

You can print the red, blue and green channels (actually cyan, magenta and yellow by the time you have a positive image) onto acetate sheets, then layer the sheets to make a physical trichrome.

Keeping a slight gap between each sheet gives a nice 3D effect. And yes, that is taking the whole thing far too far.

~ Anthony

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This series is produced in conjunction with Hamish Gill's excellent 35mmc.com. Head on over to read the other half of these stories there.

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