Quote:
Originally Posted by cometcatcher
I have seen this before a lot in my own stacks. It's not a setting in DSS. I've sat there for ages and tried all the stack settings, average, median, maximum, Kappa Sigma clipping etc etc with the same results. It's noise.
I discovered by accident that stacking two different sessions with slightly different alignment helped. What I accidentally did was dither the two sessions. If I did multiple sessions with the same alignment, the noise just got worse.
Of course the best cure for this is to have no noise in the first place. Otherwise dithering helps.
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My experience has been different.
I started off with my 1000d and haven't had the chance to look at dither with BEOS and phd, so all my dslr images are stacked without dither.
of course, noise removal isn't effective, but I don't see any of the artefacts mentioned here when I stack 15 or more subs.
here is a stack of 16x5min subs, no processing, just stacked. no dither either. I've blinked through all 16, and they barely move as I use an OAG.
taken with an unmodded stock 1000d.
https://www.dropbox.com/s/8u2uaw6m9r6y697/Trifid.png
Maxim does a very good job at stacking as well and if Max can post say 10 raw subs, I think its worth a stack attempt.
I'm also not sure what Max's mount is and how accurate the tracking was. if it wasn't too accurate, a bit of field rotation or drift does offset the series by a few pixels.
I'm fairly certain that the artefacts can be eliminated, depending on the raw subs of course.
if its noise, well he could dither next time, but if not, why waste that data?
Cheers
Alistair