The math in monochrome, or why shoot first in color
Now, think about all the information you have there. Three colours, with 256 possible strengths of colour.
256 x 256 x 256 = 16,777,216
Wow! Each dot can represent any one of over 16 million colours. That’s a lot of colours!
So what happens if you set your camera to black and white digital photography mode? It throws away all of those colours and simply records the strength of light at that pixel on a scale of 000 256.
000 = pure black
255 = pure white
anything in the middle is grey.
This is the main reason why I implore you to not set your camera to black and white mode.
If you do you are asking your digital camera, that is capable of recording any one of over 16 million combinations to choose from just 256 of them. You’re basically throwing away information that you might just need later on.