Digital Night Photography: Test Exposures, Noise Reduction, and Image Stacking « Joe Reifer
Dawn has been asking about techniques for night exposures. Here’s another of the types of things that night photographers do. “Stacking” multiple exposures is a way to get rid of some of the noise that comes from long exposures by averaging it out–this is more about stacking to get light trails when the light is otherwise too bright for a long-enough exposure. I’m not sure that putting together two (and only two) exposures in lighten mode would do much for the noise, though.