Black and White: In camera or in software?
There is a huge difference: You cannot change your mind if you set your camera to B&W. Another difference is that there are multiple ways of converting to B&W, some people do not simply use luminance and will favor certain colors during the conversion. In the film days, it was possible to use a colored filter with B&W film to reduce the resulting look. Some cameras let you control this in-camera but you have a limited number of options (0-12). Then again, if you have complete confidence it’s what you want and don’t want to waste your time on a computer, it is up to you.
