Hi Everyone,
I have caused an image defect on my RC8. Pictured are the rings that appear in each of my images no matter the direction I am facing. I am happy that I know the cause of the elongated stars, but the rings confuse me.
My imaging system has undergone several changes simultaneously so it is difficult to isolate a potential candidate. But here is the list of changes so far;
New Orion off-axis guider
New Moonlite 2 inch to t-thread adapter
New Bob's Knobs for secondary
I am using an Orion parsec 8300 Monochrome, with 2 inch filters. This is the same configuration as 2 years ago when I last imaged without the aforementioned defects.
I know that a flat will illuminate the issue but I would rather deal with the cause.
I believe that the secondary might be too far from the primary as a result of installing the Bobs Knobs, but I am unsure on how to prove this either way. Any help would be greatly appreciated.
Hi Trent, the worst you could do with the secondary being in the wrong position is cause vignetting or slightly hurt your contrast, since the scope has still come to focus - same with the new T-adapter. If your secondary is not well positioned your collimation will also be problematic, but won't cause the effect you're showing. Is there anything reflective in the OAG? This really looks like a stray light issue to me, so some shiny metal exposed in the imaging train - and - a new source of light off axis.
cheers,
Andrew.
I would put out an ask for someone to measure their secondary to primary baffle. That will give you the correct distance. Take a mean measurement from several scopes.
Thanks everyone.
As it turns out it was because of reflections. During the day I used matt paint on my 2inch - t adapter. Additionally I used a "Sharpie" on some areas of the OAG this resolved the issue.
Paul,
Thanks for your advice. My focal length measurements for the rc8 as seen on a solved pinpoint image is 1608mm. I hope this might help someone else.