This is NOT what photographers (or anyone else, except in certain printing applications) are referring to when they talk about black and white photography.
Technically speaking - and here's where it gets confusing - a true 'Black and White' image should be comprised of only pure black and pure white – no greys - the kind of result you get from a fax machine or black pen on white paper. This is NOT what photographers (or anyone else, except in certain printing applications) are referring to when they talk about black and white photography. Correctly speaking, we should refer to our black and white photos as being 'Greyscale' (because they contain all the shades of grey too) rather than 'Black and White', but no one does, and far be it from me to try and change everyone. In this tutorial, when we talked about black and white, like everyone else, we actually mean 'Greyscale'.