At the top of any list of photographic writing, I would put Edward Weston's Daybooks. Although they can be enjoyed on the surface level (which is how I first read them), the problem is that (like Alice in Wonderland) there is so much going on between the lines that an annotated version is needed. For example, it wasn't until I recently read a biography of Tina Modotti that it became clear that by the time he left Mexico for the first time they were no longer lovers, and he left in frustration because he wasn't getting any. It certainly puts a whole new perspective on his second sojourn there, when they were housemates but not bedmates. There are several biographies of Tina (a remarkable woman, indeed, and much to my surprise Weston was almost a minor diversion), while Charis Wilson Weston's excellent autobiography essentially picks up where the Daybooks left off. but there's not a single good biography of Weston himself.