I saw a video of Dan Doke photographing a wedding with two cameras.He did not bother to shoulder either one. He simply held a wide-angle body in his left hand and a telephoto equipped body in his right. When a close shot presented itself, he simple brought his left-hand camera to bear and took the shot. Ditto long shots with the long lens.Very fast, very efficient.
As near as I can tell, this is how Mr. Doke does it. I removed the lens to make the placement of the thumb more obvious. Rotate your wrist 180 degrees and you can now photograph the whole world with your left hand. Needless to say, without automatic exposure and focus this technique makes no sense at all unless you plan to make all of your shots at the same distance and under the same lighting conditions.
The ability to hold your camera in you left hand opens up many possibilites. It frees up your right hand to hold onto your monopod mounted speedlight. You can now change the direction of your supplimentary light to either side, should the situation call for it. It works well for self portraits.
In defense of what credibility I may (or may not) have, this was quick shot made outside my office, completely without pretense. No effort was made to create "art".
