Quote:
Originally Posted by Startrek
I can only recommend to go back to basics and start from the ground up due to this image having multiple possible issues as mentioned by Chris and Ryan
1/ Level tripod and set up with front leg facing True South then install mount and scope
2/Check payload on mount is balanced in Ra and Dec ( adjust slightly east heavy , move counterweights no more than 10 to 15mm )
3/ Set mount to Home Position
4/ Check Secondary and Primary mirror is clean
5/ Collimate Newt using both a Cheshire and Laser ( ensure primary mirror is not pinched, ensure secondary mirror is not slight tilted with respect to the focus tube )
6/ Ensure camera and coma corrector are fitted with correct manufacturers distance to camera sensor
7/ Ensure camera and coma corrector sit level in focuser without tilt
8/ Polar align to under an arc minute
9/ Perform a Star test ( slew to a bright star say magnitude 1.0 to 2.0 and take 10 sec, 30 sec and 60 sec subs unguided ) Check images and ensure star is round and has 4 diffraction spikes not 6 or 8
If more than 4 , secondary mirror may have tilt or spider vanes could have an offset )
10/ Run your guiding to ensure guiding error is under 1 arc sec
11/ If all of the above is ok , then image say M42 again , this time take 60 sec subs , review images and then if ok image with longer subs 2 or 3 min
Caveat
Avoid imaging during cloudy weather even high cloud
Avoid imaging in windy weather with newts ( they act like a sail )
Hope the above offers some practical advice moving forward
Cheers
Martin
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NB: A couple of important items I forgot to mention , make sure your mount is not loaded beyond its Astrophotography capacity ( general rule of thumb is around 65% of the mounts stated maximum capacity)
What mount are you using for an 8” f5 newt ??
Also check mount for excess backlash in Dec and Ra main motor drives and worm drives
What guiding software are you using when using ?