I am trying to figure out what will be the best setting on my D50 to get good pics of fireworks tonight. I think that I need to set my shutter speed to at least 15 sec and increase the aperture. How do I set the contrast so that I dont pic up the blue in the sky? I took some pics as Disney World of some fireworks but it was just really a guessing game and over 1/2 didnt turn out to be anything. Can someone please help me out?