For most people, night photography started with a digital camera… following in the footsteps of others who inspired us to get out and shoot in the dark. Our images were a little noisy and that reminded us that the higher ISO settings can give us more noise. With that, we accepted that nightscape images are generally more noisy (than daytime landscape images) because of the limits of the cameras we have available.
Introducing Stacking To The World
Astronomers have had some ability to "stack" multiple exposures to reduce noise for years. This is where we take advantage of the fact that the location of the noise dots on each exposure is different and this allows us to sort of "average" them together to get the noise dots to disappear where the points of light just reinforce each other. The result is significant noise reduction - although the software that does this is generally very expensive and overly complicated.