A little background first.... I have a shot that has escaped me for a couple of years now. There is a neon blue sign on the Qwest building in downtown Denver. I'm guessing its about 18 miles away as the crow flies. I have yet to be able to resolve that sign well enough to read the letters. At first I thought it was just the lack of focal length. I have tried out to 1000mm on different nights with no success. Atmospheric conditions was my next thought. Tried it in many different conditions and still no go. No photographic content in this exercise. Doing it just for the challenge. I'm just odd that way. :Wink: My current opinion is that a Bayer type sensor can not resolve the blue well enough. Has anyone done resolution tests based on color?