The tone 'black' slider is it black

Question

using a canon 5d when they are imported into lightroom, the files get a 5 point black (by default)in the basic tone control. This slider seems to turn some of the lower tones before black a dark red? has anyone else notice this?
If I turn this slider control to '0' and use the contrast slider below in the basic develop tone control, I get a much more neutral lower tone and the dark red effect does not appear.
If I export the adjusted file with a value on the black slider with a value other than 0 it also appears in the file
anyone have any ideas why this happens? Without using the black slider it become difficult (more steps) to adjust the lower portion of the file
thanks

Answer 1

>Do you, by chance, know why? The only reason I can think of is that it allows a little leeway with which to reduce shadow clipping.
The defaults were apparently designed to give a fairly neutral rendering with average contrast and probably represent a simple compromise. I know they tested this with hundreds and hundreds of images from different types of photography. Most well-exposed images should have only a tiny bit below 5 blacks. That said, it is normal (and often desirable) to have some real black in your images and there really is no reason in general to decrease that slider. Don't worry too much about the warnings. If it is just in a few shadow areas, it is fine. I rarely decrease the black slider, but I often increase it to get better contrast and nicer shadows, especially after adding a little shadow fill.