Most of the people will set flash to TTL mode. Yes, TTL mode is really good, especially on nikon system. But still, when you are facing stage performance, crowds, and some shots which cover a large area of black space, your flash will put out a full power. This always happen with you are not on a direct flash. The fastest way to overcome this problem is to use manual mode. Take note of your flash and the subject distance. Using a direct flash, TTL will still be ok, in return, you will have a really hash flash, and alot of noise in your background.