Hello, hopefully this is the right subforum for this question!
I recently bought a new fast Newtonian, Sharpstar Hyperbolic Newtonian 150 F2.8 (6", 420mm FL, F2.8) and I've noticed that some of the brightest stars in my image show faint concentric rings. I was wondering if anyone may be able to shed some light on what may be causing this. I'm thinking perhaps internal reflections from my Ha filter?
The following image is a 4:1 crop of Eta Carina. It is in the center of the frame but I noticed the same effect with another star near the edge.
EQUIPMENT IN OPTICAL PATH
Sharpstar 150 Hyperbolic Newtonian (6", 420mm FL, F2.8)
Optolong 36mm, 6.5nm Ha filter
single raw 180s exposure, stretched
Any advice welcomed, thanks