Quote Originally Posted by tkerr
Stacking multiple exposures vs a single or only few longer exposures improves the S/R(signal to noise ratio).

Many people make this claim, but it is not true. There are several good reasons to stack, but improving SNR is not among them.


Photon noise is not affected at all by stacking (ie, 10 one minute exposures stacked or one ten minute exposure will have the same photon noise and same signal, and thus the same photon noise / signal ratio). Read noise is actually worse when you stack.