I find it all pretty ridiculous. I haven't shot much on the street with anything greater than a 50mm lens, but if I need to, or want to, no rule is going to prevent me from doing so. Likewise, no rule will prevent me from shooting a subject from behind. I really like the feeling of such images. True these images are far less engaging—in the sense that nothing quite grabs a viewer's attention as much as an image with the subject staring directly back. However the quality of an image in which the subject is shot from behind is unique. There is a detachment, or a detached quality. The detachment seems to strip a layer of understanding from the viewing equation, forcing the viewer to derive meaning from the subject's surroundings. It's an odd phenomena. Without a human face, but with a human form, we seem to search for meaning, deriving it from whatever we can.
The first photograph that I can recall that distinctly and prominently featured a subject shot from behind, and the one that made a huge impact on me was an image created by Lisette Model. The photograph was of a large man, in a tight fitting t-shirt with thin horizontal stripes (sorry, I can't find this image online right now). The man wears a beret, and he is sitting on a bench. The subject fills about 80-90% of the frame . It is very simply an image of a large man shot from behind. It's an image I'll never forget having seen, yet I still don't know why it has had such an impact on me. Many photographers such as Joel Meyerowitz and Daido Moriyama have used this "technique," to create very memorable images, as well.
Damn the "rules"! Break the "rules"! Make your images.
