I was walking at night, taking flash pics of the kids the night we arrived at Black Butte Ranch, OR, it was the very first outing with my new 5D Mark III body. I was also using a 430 EX II with a simple slide-on diffuser and a 24-105mm L lens.
Never mind the obvious focus issues of the photo, what the heck is going on in the lower right corner? Is this an artifact from a focused LED headlamp hitting the sensor in a weird way, or did I get a lemon body?
I shot about 800 frames, including 50 with night flash like this, over the course of a week, and this is the only frame that had any such issues. Any brilliant insight out there, should I be concerned?