From my experience this is a pretty common trait found in sports photographers. Since they are often using longer lenses they can blind themselves to action on the rest of the field, so letting their other eye wonder helps them stay fully aware. It is especially important for sideline photographers (football), as it helps them and their gear avoid being trampled.


It is a pretty cool trick, and certainly has its uses, but I find that it only works for me in some situations, where in others I want to concentrate fully on the subject at hand.