Color in photography is always an approximation, there is no direct link between the colors of the surrounding and the colors registered by the camera. Except for the Lippmann process I believe, and maybe another one that now I can't recall.
Visible light is some spectral distribution of electromagnetic waves in the wavelength range of 400-700nm. This is what hits our eyes. Our eyes have three types of sensors for these waves with different sensitivity at each wavelength. This provides our brain with three signals from which to form color information. Some spectral distributions will look the same to a few, but different to others, because you map the much larger space of "all possible spectral distribution functions" into the much smaller space of "all number triplets". Not all eyes and brains are created equal, so there will be great differences in perception even if people look at the same scene.
If you use color negative film to record a scene, you have silver halide crystals sensitized to different wavelengths of light. These spectral sensitivities will inevitably differ from what our eyes sense, but for most practical purposes there is a good match. Once the film hits the color developer, dyes are formed, which usually affect one very specific wavelength. This film is then projected onto some RA-4 material, which has spectral sensitivity closely matching the spectrum of the C-41 dyes. The dye spectrum of the RA-4 material is then what your eyes get to see. Note, that the spectral sensitivity of each material can, but doesn't have to be aligned with the spectral density of the dyes created during development.
In addition to this simplistic (haha! ) description there are some effects:
- our eyes create adjacency effects, i.e. a blue patch right next to red patch appears different to a blue patch next to a green patch
- there are temporal effects: looking at a red patch for a minute, then looking at a blue area creates funny visuals
- there are adjacency effects in film, where development in one color layer affects development in other color layers. That's how vivid color palettes are created
- Some processing variations will create differences in both density range and in dye hues. Different light sources with their very different spectrum will create different visual appearance of film dye, too.
- Finally there will be a big difference whether the pic you look at covers most or just some part of your field of view, that's how our eye/brain system works.
So yes, every film will create a different palette, people (even those with pilot grade 20/20 vision) will perceive the same palette very differently, and even processing defects will provide you with different visual experience. I have no idea, how to wade through this mess except for confirming your suspicion:
Once an emulsion is not manufactured anymore, its color palette vanishes with it. So, when photographic technologies evolve toward a more performative film (for example, Kodak Vericolor becomes Portra) we observe a technological loss.
Yes, there has been howling and grinding of teeth whenever a landmark emulsion disappeared from the shelves.
@Rudeofus , you mean that these compounds are made for the purpose of being a photographic dye only?
Yes, absolutely. Kodak, Fuji and Agfa were all large chemical outfits with a small coating station attached to it. They synthesized compounds of incredible complexity for these two very specific purposes: spectral sensitization of film, and dye couplers for film. Some spectral sensitizing dyes are also useful for special laser devices and are sold commercially for multiple hundred dollars per gram, but even with these I am not sure whether they even have a CAS number, much less a name.
PS: Kodak did quite a bit of research into how people perceive colors and especially color photos. These articles may be a valuable resource for your efforts.
