Very weird star shapes across field

[Danield06]

Hello everyone,

I have had this issue for awhile and I can't seem to pinpoint what it is. Others cannot understand it much either. I'm not sure if it's my telescope or If it's just tilt/spacing issue.

One thing I noticed is that I always have elongation from the bottom left to the top right. My next issue is that I have these "wing" shaped stars. Maybe astigmatism from tilt? 

Any help would be appreciated. Images are below and I will post a drop box of a fits file.

The two image below are the center of the images. Pretty much all stars look like this throughout. The third image is a full view of my image, with some cropping. 

 

Dropbox: https://www.dropbox.com/s/1o8q33165n8qg06/Sadr_Light_Ha_300_secs_2020-09-07T03-33-55_017.fits?dl=0

Edit: r

- Meade 6000 80mm APO

- hotech FF

- ZWO EFW, ZWO ASI183MM

All help is appreciated, thanks!

 

 

Edited September 10, 2020 by Danield06

[MeyGray3833]

Hi. Can we have a bit more of a close up?

[Danield06]

6 hours ago, MeyGray3833 said:

Hi. Can we have a bit more of a close up?

Hmm..Im not sure I can get much closer, feel free to download the drop box link and take a look though. I can get you more subframes as well. I'll see what I can do about being more cropped to get a closer look. 

[Pryce]

Are the elongation always in the same direction for every session? 

Has it always been a problem with that telescope/setup or has it slowly become worse over time?  

Try to rotate each piece in the image train individually.  Start in the back and move your way forward. 

If it happens with one device specifically it might help with the troubleshooting. 

 

I recently saw a video by Dylan O'Donell from Starstuff where he has a similar issue.  The problem was that he has more error in the RA axis than in DEC. 

Maybe this will help!

 

[Danield06]

2 hours ago, Pryce said:

Are the elongation always in the same direction for every session? 

Has it always been a problem with that telescope/setup or has it slowly become worse over time?  

Try to rotate each piece in the image train individually.  Start in the back and move your way forward. 

If it happens with one device specifically it might help with the troubleshooting. 

 

I recently saw a video by Dylan O'Donell from Starstuff where he has a similar issue.  The problem was that he has more error in the RA axis than in DEC. 

Maybe this will help!

 

That's a good observation, I did have an RA issue that I did work out. It's definitely not a tracking issue. I did have both, but tracking error is now gone. I can confirm that too. It was east to west and there is no longer east to west elongation, it was mitigated eventually, but took me a month. I am thinking more along the lines of astigmatism from backspacing plus stiff tilt somewhere. The "elongation" your seeing I believe is astigmatism/tilt and I have been able to slightly change its direction when rotating my imaging train. It's in short 1" exposures and longer 300" exposures and always the same size.These are guided as well. I still have to okay around with everything though. Looking for some more idea. IF there still is elongation from tracking then I need to figure out this issue first because it is probably being masked by the diffraction/astigmatism or whatever the heck it could be! Lol

Edited September 10, 2020 by Danield06

[Pryce]

If it's in both 1" and 300" exposured I'd assume it's not a tracking issue. Especially since it's changing it's position when you rotate your imaging train.  Try to rotate each unit individually so you can find out which is causing the issue.  Hopefully it's not a problem with your optics!

Edit: But I don't really know, because I'm noob 😀 

Edited September 10, 2020 by Pryce