stars like little doughnuts,(donuts).

[piprees]

Hi guys,
My stars come out like little doughnuts. It may be an inherent imaging problem, (could be collimation), but has anyone had this problem and more importantly, how did you deal with it? It could probably be solved with a mask, unfortunately I've no idea what I'm doing with a mask so please be gentle. Any explaining needs to be as simple as PHD.
Hope someone can help,
Kind regards,
Phil

[Cheman]

Hi Phil
How was your focus? What type of scope were you using?
Let's try to get to the root of the problem first, then you won't have to worry about trying to fix it in Startools I'll let someone with more knowledge try to help you with repairing with Startools
Che

[piprees]

Hi Cheman,
It's a Canon 40D on a 200p on a Neq6, guided with a qhy5 11 with phd. Polar alignment was spot on as was focus with a batinov mask. It was of the dumbbell and took 34 x 150 secs plus 7 darks and 7 bias. I'd upload it but I don't know how to, (lol), but I have managed to upload it onto flickr under philrees51.
The set up is pretty standard really but then it may be me expecting too much from it.
Thanks for replying,
Regards,
Phil

[almcl]

Are the doughnuts on all the subs or do they only appear after stacking? I have had this latter problem when DSS was trying detect hot pixels.

[piprees]

Hi Almcl, no, they're not on the subs only after DSS. I noticed them when I started to process the stacked image.
P.

[Cheman]

Interesting. thinking about it, I have seen this in DSS before, Did you try changing the Filter Size and/or Detection Threshold settings in DSS for Hot Pixel Detection?'
Dont know if it will help or not.
Che

[Cheman]

getting back to your question about how to fix this in StarTools.
You could try
mask the stars, in Mask, Auto>stars>do(use defaults) when startools is done, keep the mask.
Now open the Repair module and try out the Warp function or the redistribute feature http://www.startools.org/modules/repair
Also you can try the Magic module in the same way(shrink, tighten) http://www.startools.org/modules/magic
there may be other/better ways that Ivo or someone else can suggest, But give this a try.
Che

[almcl]

Check to see if hot pixel detection is (on the Dark frames tab in stacking parameters) is on, if so, uncheck it.
Also uncheck automatic detection of hot pixels on the register settings menu.

[piprees]

Thankyou guys, I'll give all these a try.
P.