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Bill,
I just thought of something which hasn’t been raised as yet
Make sure your focuser tube is not obstructing the light path of your optical light cone. This can cause flares on one side of your stars !!
A coma corrector with long barrel can cause the same issue.
Also from memory SW Newts have focuser tubes painted Matt silver ( got me buggered why they’re not Matt black to minimise reflection etc… is yours silver ?
I feel your pain , there have been so many folk on this forum over the years starting off imaging with entry to mid level f4 Newts ( Skywatcher , GSO and similar ) and running into problem after problem.
The higher end f4 to f3.8 Astrographs never seem to have too many issues as they are a precision quality engineered scope and nil internal reflection.
When I started imaging back in 2017 , a bloke at Bintel recommended I go f4 as it provides more light gathering power and a wider field of view. After research on many forums I decided to stick with f5 for all my Newts as the products they were offering me were entry level budget type f4 Newts plus I didn’t want to spend big bucks on a high end premium f4. The f5 is so much more forgiving than the f4 and that was the determining factor as a newbie at the time.
I’ve never had an issue with any of my f5 Newts ( 6” , 8” , 10” and 12” ) and any minor issues have always been cockpit user errors.
I check collimation every few months , they just hold collimation these f5’s irrespective of temperature ( Ive use carbon tubes in the last 3 years and built all my Newts from GSO parts )
I still reckon your issue is a combo of many factors that have been mentioned so far. Another point is that when your up at the zenith your punching through less atmosphere so any optical aberration whether reflective or mechanical will be marginally less in effect.
Anyway have a look at your focuser tube to see it protrudes into your optical path.
I do hope you resolve the issue sooner than later but it’s going to take time and plenty of clear nights
Good luck
Martin
Last edited by Startrek; 29-06-2025 at 07:35 PM.
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