I am a recent owner of a Minolta Maxxum 7D. In the course of testing out the camera I have determined that its ability to render accurate colors when shooting in natural daylight is excellent with very little adjustment ever needed.
However, when it comes to shooting under fluorescent lighting it is very "hit or miss" and with tungsten it is not great in my opinion. This is all of course based on testing done with AWB, Preset WB options, Custom WB experiments, and even manually adjusting the Kelvins. Therefore, I started to wonder. What sort of results could I get if I used the Cokin fliters I had that I use for shooting under those lighting conditions with my film SLR's? Wonder of wonders, I found that I could get more accurate color rendition using them.
To make a long story short, I started out doing the testing with the camera set manually to 5500K. That is often sited as the default Kelvins measurement for daylight, which of course is what the filters are geared to compensate for when daylight film is used under the other two types of light source. (Bear in mind, I am a person who likes "cooler" images more than "warmer" ones.)
What I discovered (based on the lighting in my home as obviously opposed to that in your's) was that if the Kelvins were set to 4600, and the applicable filter was in place, that I got better color rendition accuracy than if I used the camera's own built-in means for compensation for the given light sourses.
The 4600 number was the best compromise between the 4900 that seemed best for tungsten and the 4300 that seemed best suited for fluorescent. (I wanted to find a compromise Kelvins number because I wanted a default setting to use for Register No. 3 which was going to be allocated to indoor non-flash photography.) (For those who don't understand what a "register" is in this discussion, it refers to a collection of camera settings that can be memorized and recalled in the camera for ease of convenience. Not all D/SLR's have this option.)
With the filter for tungsten light, I am losing at least 1EV because of its use. However, since my default ISO setting for this register is 1600, I am not too badly affected.
I am pleased to have discovered that using filters made for film photography may actually make my digital shots better.
Has anyone else experimented in this use of filters too on DSLR's, or seen the same sort of benefits I have by doing this?