Camera manufacturers are sneaky bastards: they will do anything to force you buying overpriced original equipment and accessories. That includes writing a piece of code in camera firmware which will make cameras incompatible to some 3rd party flash units, what I found out earlier this afternoon in a very annoying way: buying a flash which would not work on my Canon EOS 6D. It’s a Yongnuo YN468 speedlite flash that I bough second hand for around $50. The guy that sold it to me said he hardly ever used it. It sure does looks like new and when I tried it before buying, it worked just fine. The problem was I tried it in daylight on a parking lot and could not know that there will be issues in real use.