Quote:
Originally Posted by Doug
I have heard of rotating the imager when imaging light frames to cancell out dust motes, but even so, a flat to get rid of vignetting would be marginal at best.
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emphasis added.
Paul, Dust motes are not unique to flat field frames. If one were to take several light frames, each rotated, then when those light frames are combined using a median or Sigma or Sigma clip type algorithm any outlier pixels will be eliminated...cancelled out. This will include cosmic ray hits, dust motes, hot pixels meteor trails, mostly satellite trails aircraft light trails etc.
I agree it will not do a lot for flat fielding images; I think the idea is to avoid the need for flats, which if vignetting is not an issue will work.
Doug