Quote Originally Posted by DWThomas View Post
You would have to experiment, but it might work about like an orange for black and white -- dunno, never tried it.
The standard B&W orange filter #21 or similar has a very sharp cut off, like other filters designed primarily for B&W. The Wratten 85 filters have a much more gradual slope, and are a color biasing rather than a cut off filter. The different 85 series filters just have variations on that more gradual slope, and won't increase color contrast nearly as dramatically as the orange, or even yellow B&W filters.