CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
Nice observation Andrew. Its due to poor matching in the stacking due to small play in the T-ring resulting in the focal plane not flat. I cropped quite a bit of the image to remove those parts.
Hmm... my focuser and T-ring have quite a big (not small) amount of play, but I never seem to have this type of problem after stacking... did you perform registration and alignment or you just stack??
Have a nice day.
Yang Weixing "The universe is composed mainly of hydrogen and ignorance."
I did a 2 star alignment for stacking. Due to some trailing of the images, thats why the matching is not very good.
You mean it's cause by some images that had star trail in it?? I also face this issue before, but the star trail disappear after I perform the stack. Below is the method I do (should work if quantity of your star trail images is less than those good images) and may be you can try it:
First, I separate those images that had star trail and those images that do not have star trail. I first perform auto registration and alignment on those images that do not have star trail. After the software generate the aligned images, I select one of the aligned image and use it to perform manual registration and alignment on those images that had star trail. After the software generate the aligned images for those image that had star trail, I stack all the image (using Sigma clipping method) together and the star trail will disappear.
For that, I must bang my head for being lazy to bring GPD2. Haha!
What mount did you use?? Since the Megrez 80 FD focal length is quite short, you should just do a good polar alignment and shoot unguided.
Have a nice day.
Yang Weixing "The universe is composed mainly of hydrogen and ignorance."
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
Hope you don't mind if I try to process your image a little further. Just done a simple colour balancing, brought up some structural details and smoothed the image a little.
Weixing:
Thanks for the tips. I will try that when I have better data. Hopefully with ATIK and VC 200L. Actually I went to desaru without testing equipment. EQ-3 was overloaded with Megrez 80FD and ST80 on top of it. Tracking was not that good even if polar aligned. So all intention to take deep images blew off.
All of you reading this, please learn the lesson
Andrew: Bring EQ-6 ????!!!! Oh man, that monster is meant to stay on the rooftop.
Remus: Hey thanks for the great improvement in processing. Initially I tried to push a bit also, but the background posterises easily, so in the end, I leave the pic highly untouched. Great improvement here without that much posterisation in the background. Thanks.
"The universe is composed mainly of hydrogen and ignorance." 
