As Bill mentioned, photographs of photographers is one of my niches of collecting, and I pick them up whenever I can to go along with my off-and-on research of sports photographers. There are several pictured in the thread here:
http://www.net54baseball.com/showthread.php?t=175907
I know that George Burke in particular used a Graflex camera that originally held 5"x7" glass plates and which he converted over to use 5"x7" film in the 1930's. George Brace also used a Graflex, though a later version of the popular camera which was smaller/lighter and held 4"x6" negatives. Norman Paulson likewise used a Graflex early in his career, though I am not sure which model. All three of these would have been actively using a Graflex in the 1930's. A photo of Burke's camera is below.