Here is an image of Comet LINEAR 252P captured with the KPO 18″ Reflector. The green color is from the Cyanogen gas that makes up most comets.
Image Info: Canon 60D with an Astronomic CLS LPR in-body filter. 37 subframes at 120 seconds each, for a total integration time of 74 minutes. Two stacks were aligned on the stars and the comet respectively in Nebulosity. Each stack was then processed in StarTools, an then the separate images were integrated in PhotoShop. Finally the image was tweaked in Aperture.