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I was creating some new master flats and chose "Automatic" as the integration method. I loaded 30 subs, yet APP still used median as the integration method when I read the output from the console as it was working. This is in contrast to what I've always read that if you have more than 20 subs you should choose average.
Is this correct behavior?
Yes indeed, that is correct behaviour.
For masterflat creation, the automatic integration will always use median integration. Reason being that it prevents a lot of issues with flatpanels 😉 and/or short exposed flats. Simply said, to get a proper masterflat, in most cases, median integration of your flats is much more robust for good flat-field calibration.
And yes, for bias, darks/darkflats, lights you definitely want to use average over median with more than 20 frames. Reason being that average integration is superior to median integration when it comes to noise reduction, and that fact... is almost never a problem with MasterFlats. The Signal to Noise Ratio is already very good of single flats, let alone of a MasterFlat.
So the rule does not apply really for flats. If you have good stable flats, then by all means integrate with average if you wish, but it will very likely not affect the noise levels in your final light frame integrations significantly.
Kind regards,
Mabula
Excellent. Thank you so much for that quick reply.
