Gast
This isn’t really an answer to your question, but anyway:
In my opinion, the best approach is to use just one filter at a time – magenta for a harder look and yellow for a softer one – rather than mixing magenta and yellow. Of course, the exposure times will always change when you adjust the filter head. But the times aren’t really consistent even if you use a ready-made table. After all, the contrast doesn’t just depend on the colour head, but also on the paper used, the developer, and probably all sorts of other things as well... I once had a table like that and it just caused me confusion – you always hope that the time can be kept constant; sometimes it works, but just as often it doesn’t, and in the end (for me at least) there’s a lot of confusion. With the above ‘tip’ (from a professional), things are going better now – over time, you get a good feel for how to adjust the time when turning the filter and always know exactly what you’re actually doing.
The big advantage of the whole thing is that you don’t just have full and half gradients at your disposal, but can adjust the contrast continuously. That’s precisely the beauty of using a colour head for black and white.
