[baro-nite]

Thanks Michael. "Physics" and "simple" aren't usually words I use together. I should have been clearer; was really asking about RioRico's statement that using a red filter gives a slight increase in dynamic range.

DAZ: great set, and a great mini-tutorial on using B/W.

[RioRico]

Thanks Michael. "Physics" and "simple" aren't usually words I use together. I should have been clearer; was really asking about RioRico's statement that using a red filter gives a slight increase in dynamic range.

I can't find the sources, but I know I've seen the RedFilter/DynamicRange datum in several places. Meanwhile, here is a valuable reference on filters:

Filter options for digital cameras

Back to the original question and the first answer: "A lot of b&w photos are saves of photos which had significant color issues." That's so true! If the colors suck, go mono. If the shadow details suck, black them out. If it doesn't look photographic, posterize it. Do whatever it takes to make it viewable.

[DAZ]

It has been a long time since I have done darkroom work but the only thing I remember about a red filter expanding contrast and B&W was that you used a red filter to expanded contrast on the enlarger. B&W papers don’t respond to all colors the same (that is why you can use a safety light with B&W) and using a red filter you could expand the range of the negative on the paper to get the max (D-Max to D-Min) out of the paper. That is the maximum density (black) to the minimum density (the white of the paper).
Other than that color filters were used on the camera to block colors that were specific to something. For example if you wanted the cyan sky darker/lighter or green things darker/lighter. You can do this now PP.
DAZ

[Kerrowdown]

When/what kind of photo would you make it black and white

In my music photography, where the artist or performer has been lit with only low levels of coloured light, especially red.

PP to B&W is sometimes the only way to get a really usable image.