Long Exposure and Noise
It’s a strange thing, but take this little bit of gem that I learned today. This is really only going to be a problem for night time celestial photographers (although I’m sure there are other instances that I cannot think of at the moment).
Comparatively, a single shot at relatively faster speed at 1600 ISO will have less noise than 20 shots at a lower speed with ISO 100, stacked on top of each other.
Yes, I didn’t believe it either. It all has to do with the randomness of noise and how the sensor actually deals with the noise. The random effect that is produced and is doubled and duplicated during stacking will make produce an image that has more noise than if you had taken a single shot at a higher ISO. I’m sure there is a cross over point at which this is more prone and even more true, but I have not done enough testing and reading to be able to tell you what that is, but for now know that 1 shot at a higher ISO is usually less noise then a stacked of images at a lower ISO.
