An In-Depth Look at Contrast and Telescopes With comets, as I said before, contrast is the name of the game. Comet hunters are looking for elusive and shy objects.
Contrast is also something urban observers struggle with in order to improve general viewing.
Comet hunters are well advised to look at the devices employed by urban astronomers to improve contrast. In the city, all that light from street lamps is scattered off water vapor and other pollutants that are a part of city life. The light pollution effectively changes the color of the sky from black to something ranging from dark blue to orange or pink. Comet hunting from the urban location I live in is, at best, a major handicap to my chances for success. So the best thing to do to improve contrast is move you and the telescope away from contrast-robbing streetlights.