That's not true, or is, depending on your shots. I notice in one of my fan films that there is an overexposure in the back round in a few shots. All of the sudden the guys light saber blade is gone, it just doesn't look right. It is distracting, like a continuity break, or like, oops who forgot to finish those shots. When the blade disappears, it break's the suspension of disbelief. Even in the star wars movies, there are several shots in which light sabers should disappear but don't for the very same reason. As I said, if you tweak the adjustments correct. Besides, when you watch a light saber fight, the last thing you should think of is, hey, light cant bend, light sabers aren't real, ect. ect.