Ok, I thought I used to be able to take pictures of christmas lights, but I guess not. What am I doing wrong??? The lights are always blown out, or the rest of the house is black. Should I have a low f-stop or high f-stop? What other settings (filters?) would help? Nikon D50 AS-f Nikkor 18-55mm 3.5-5.6 F18 30" 20mm OTE.