I have a canon 50d + 28-135mm USM lens. I went to Vegas last weekend and I'm not really happy with the way it turn out with my picture while taking them at night in Vegas. Even though, there are alot of lights but somehow the pictures turn out weird. It even didn't help when I put on the canon speedlite 430 EX II. Every pictures with the flash on has a bright area around the faces, what I really want is to see the light and the area of the background. What is the best lens for taking picture at night?