There is so much nonsense about the use of photographs, but most important is the issue of copying them. Why not use a photocopier and be done with it?
The truth is, that the camera ALWAYS lies! Shadow and light remove colour from objects,lenses distort,even the inks used in printing are only approximations. Because this is so, you must interpret,interpolate,simplify:all manner of things. The aim is not to copy the photo, but to create an illusion. Behind the illusion lies the artists knowledge or lack of it, and that is revealed as brutally as in drawing from life.
In fact, the well constructed life drawing reveals more than the photograph ever can, because the artist sees “through” the accidents of light. It is a question of the “long look” over time, which is demanded of the viewer of the drawing as well as the artist. The focus keeps moving, so that “depth of field” is constructed from myriad perspectives, not the single, fixed,lens-bound monocular vision of the camera. A similar argument appies to colour perception, where the artist reacts to after-images and simultaneous contrasts in different time contexts.
This is not to deny that the camera “sees” things we cannot normally see. It just means the camera extends our potential range of vision and subject.