Help desperately required!

[uhb1966]

Autosave.tiffAutosave.tiffHi all,

 i'm back into imaging and i have a huge amount of trouble

Please check out this test picture: the stars are formed like eggs, but not regularly - their forms seem to be all over the place ?! What things am i doing wrong? I'm using a reflector with a baader MPCC and a vintage qhy8.

Ive done way better pics with the setup? Autosave.tiff

Edited October 2, 2023 by uhb1966
added jpg

[michael8554]

The central stars have coma, so Collimation may be out.

There is also Tilt, as the right side is worse than the left side of the image.

The asymmetrical vigneting may be a feature of that Tilt.

Michael

[carastro]

There is also vignetting but perhaps you didn’t bother to add flats for this demo photo.  

[uhb1966]

@michael8554 "Tilt" ... i was afraid of that word!

@carastro yup, no flats, but thanks!!

 

[uhb1966]

I just realized that the spacing to the MPCC was way out 😕

 

[uhb1966]

@michael8554 yes, collimation was also suboptimal. I also exchanged the 2" extension - lets see if it helps. Thanks!

[ONIKKINEN]

I see tilt was already mentioned, but i will further complicate the topic by mentioning that there is no easy way to tell the difference between tilt and collimation because they affect the image similarly. Really you should think of both issues as a core part of collimation.

[uhb1966]

@ONIKKINEN @michael8554 @carastro Thank you all ! i adjusted the mpcc distance, recollimated and changed the spacing between scope and camera, and i got crisp round stars - even unguided at 2 mins. But i got into 2 new problems stuff for another post. Thank you again 😍

 

[SkyPhil]

You may want to clean your optics as well. 

Phil