Mottle background and star halo

[asterix2020]

I took this last night, 12 subs, 150 sec each, ISO 1600 CDS-600D. Stacked in DSS in comet mode. I'm getting a weird background mottling and some flare/haloes around stars, most obviously on the brighter star.
Any ideas of what to do to improve it? Or is it just a limitation of the data.
http://www.astrobin.com/full/91762/0/

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StarTools 1.3.5.279
Mon Apr 21 12:56:49 2014
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File loaded [E:\Astrophotos\2014-04-20\jacques20140420.FTS].
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File saved [E:\Astrophotos\2014-04-20\jacques20140420.tiff].

[admin]

Hmmmm... I'd definitely expect more from that data.
Any reason why you stacked in comet mode?
I'd love to have a look at the stack itself (or a crop of it) and see if we can pinpoint the problem...

[asterix2020]

I'm uploading the stacked files to my onedrive and will post the link when it's done.
I used comet mode as Jacques is moving so I wanted a stack of the comet with normal (not trailed) stars. What's weird is that DSS shows a normal image, but when saving as a TIFF it makes the brighter stars into donuts. I saved it as a FTS and it doesn't do that. I am uploading both so you can see.

[admin]

Thanks for that - it's very helpful.

Looking at the data, it appears the data has been stretched and (worse) comes from a JPEG source or similar.
Did you shoot RAWs?
If so, can you confirm you did not use any other tool but your stacking tool? (e.g. can you confim you did not use any other conversion tools to convert RAW to TIFF or FITS?)

Whatever was applied to the the data, it has destroyed any faint detail and has created filtering artifacts (which looks like the mottling when stretched).

Any idea waht may have happened?

[asterix2020]

No idea. I just did what I usually do, stacked my RAWs (yes only shoot RAW) in DSS and then saved the file from within DSS. So I guess the problem is somewhere in my DSS settings? But they are the same as my other settings that I have used except I used median instead of average method (or the other way round, it recommended one for the comet stack). I did move the slider in DSS on the top right to stretch the image to see the comet so I could mark it, but I thought this didn't affect the data if I didn't save with the changes?

[admin]

No idea. I just did what I usually do, stacked my RAWs (yes only shoot RAW) in DSS and then saved the file from within DSS. So I guess the problem is somewhere in my DSS settings? But they are the same as my other settings that I have used except I used median instead of average method (or the other way round, it recommended one for the comet stack). I did move the slider in DSS on the top right to stretch the image to see the comet so I could mark it, but I thought this didn't affect the data if I didn't save with the changes?

Very, very odd. Could you post a single raw file for me?

[asterix2020]

PM'd

[admin]

I don't know what to tell you.
Your CR2 looks fine and is definitely not stretched like the stack.
I was readily able to pull out the comet (with hints of a tail) from just the single frame, suggesting you have some great data when everything is all stacked properly.
Something is definitely going wrong somewhere inside DSS!

JACQUES_LIGHT_150s_1600iso_-12c_01062stdev_20140420-20h01m02s977ms.jpg (597.96 KiB) Viewed 10176 times

[asterix2020]

Thanks Ivo. I'm guessing it's something to do with the comet stacking in DSS. I'll have to looking to it more.
What did you think of my Thor's Helmet image?

[asterix2020]

What's interesting is the mottled glow around stars which I think is giving this background (it's most noticeable around the bright orange star) is offset in the same direction as the comet's motion. So it must be something to do with the stacking. I think the mottling is a small smeared halo around every star.