He probably thought that he is far enough to take the pictures. But thats what you get when you underestimate the speed, agility, and power of these wild animals.
While I think the dead guy's an idiot for provoking the big cat (if it's in fact, true), I don't think he deserved to die. Have a hand chomped off? Maybe.
But, not mauled to death. He's still a human being.