Thanks alian - i now have both books and love them! i have started reading them before my travel....and am hooked!
Glad to be helpful. If you like Barthes, then "La Chambre Claire" is his text specifically about photography. The title literally translates into "The Light Room", a pun on the original name for the camera "Camera Obscura", obscura meaning dark or shadowed.
I don't know if it has been translated in English. I have all his books in French.
There are also interesting asides on Photography in "Le Systeme de la Mode" "The System of Fashion" in which Barthes studies fashion and fashion photographs from the perspective of semiotics. I like it for its usefulness towards understanding composition from the perspective of how visual signs are used in images.