Quote:
Originally Posted by Peter.M
here is the point that I use for my decision to take longer subs. If you agree that longer integration will always be better then surely its better to take 20 long subs where the stacking isn't hit by diminishing returns too hard.
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The diminishing returns are related to the total exposure, not the number of subs (at least so long as your subs are long enough to make read noise insignificant).
Quote:
Originally Posted by Bassnut
In my experience, Median does excellent noise reduction.
To quote directly from the CCD stack manual (with Median) "Data rejection is not necessary (though it is acceptable) because median is a de-facto data-rejection algorithm".
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That's true but it comes at a cost in SNR - you lose around 20% using median instead of average. An average combination with a well chosen rejection algorithm and parameters will generally give you the best of both worlds. At least, that's what the maths says
It seems to work in practice as well, at least the couple of times that I've done a comparison.
Cheers,
Rick.