My question is, what is the process of getting the correct white balance when shooting with a film camera? Is it the film that determines the white balance or is it the processing method in the darkroom?
The quick answer is
both!
Film photographers don't really talk about white balance, rather they talk about color temperature and daylight balance vs. tungsten balanced film. Color temperature refers to the shape of the spectrum of your light source. Balance refers to the sensitivity of film to a certain kind of spectrum.
Most color film is "daylight balanced," meaning that its sensitivity to red, green and blue light matches the intensity of red, green and blue light as it is found in sunlight. Photographs of subjects illuminated by sunlight and taken with daylight balanced film should be correct. However, photographs of subjects illuminated by tungsten light (e.g., incandescent light bulbs) will have a reddish cast because tungsten light does not have as much blue light as sunlight. This is very noticeable in the skin tones of Caucasian subjects; they appear to have very red skin, as though sunburned. There are three solutions to this problem:
- Use flash. Strobe flash units emulate sunlight.
- Use a blue filter. I think the filter normally used for this is an 80A. It allows blue light through while attenuating the red and green so the resulting light is close to sunlight. The down side to using an 80A is that it absorbs two stops of light. If you are using an external meter you need to re-rate your film by two stops, e.g., rate ASA 100 as ASA 25. I find the use of the 80A to be problematic because when shooting under tungsten I already don't have a lot of light; the loss of two stops adds to my troubles.
- Tell the lab to "correct for tungsten." Take my word for it, this does not make your lab tech happy. They do not like having to re-adjust their equipment. Every time I've done it my prints have come back with a note (sometimes an in person lecture) about flash, filters and tungsten balanced film.
Ah, tungsten balanced film, which is more sensitive to blue light than to red and green, thus eliminating the need for a blue filter. Shooting tunsten balanced film outdoors under sunlight puts a pronounced blue cast on the print, so you need to use an amber filter, an 85. The 85 only absorbs 2/3 stop of light, usually not a problem in daylight. The down side to tungsten film is:
- As far as I know the only tungsten balanced films available today are slide films, and ...
- ... these films are very slow.
The only example of a tungsten balance film that I can think of offhand is Kodak E64T. (E for ektachrome = slide, ASA 64, T for tungsten.) Fuji makes a similar film.
Just to satisfy the pedants I should mention that tungsten films come in different color temperatures, usually 3200 and 3400 I think. You may need a different filter than the 85 but IMHO the 85 is close enough.
Another kind of light is fluorescent, which leaves a green cast with daylight film. The FL-D and FL-B filters are used with fluorescent light, the former with daylight film, the latter with tungsten film.
If you want to be even more precise use a gray card. If your entire roll is exposed under the same light take a shot of the gray card as your first and last exposure on the roll. Or include the gray card in each shot with the intention of cropping it out later. Choose a lab willing to cater to your desires and tell them about the card.