I’ve been experimenting with Trichromy / Trichromie process in the last few months. It’s a process where three black and white images are taken, with a red, green and blue filter, and overlaid to create a colour image.
At first it was difficult to obtain the correct filters, especially the blue. I experimented with the Hoya 80A in place of the proper blue separation filter and playing with the exposure compensation. I’ve now obtained all the correct Wratten colour separation filters and below are an example of the images I’ve been producing.
The Russian photographer Sergey Prokudin-Gorsky is particularly famous for using the technique and it is how I discovered it. For further examples of images taken with this method search for photographs by Sergey Prokudin-Gorsky.