Quote:
Originally Posted by Peter.M
So you think that the 21st sub will give the same noise reduction as the third? Personally regardless of the maths, top photographers are getting better results from longer subs and that is enough for me.
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I believe what I said... sqrt(10 x 10) = sqrt(5 x 20). Once you can ignore read noise the SNR from a stack of 10 x 10 minutes subs is the same as a stack of 5 x 20 minute subs. This is not inconsistent with the Starizona table.
For narrowband filters the number of photons collected is much smaller and longer subs are needed to minimize the effects of read noise.
There's nothing wrong with long subs but there's a point where the gain is small and the risk of losing a whole sub due to a cloud or a tracking error becomes more significant.