I just picked up a new C6 SCT from a CN's member at a great price who didn't wanna deal with the diamond ring effect on bright objects he had on the first night he set up his scope.
I'm surprised that over the years, Celestron continues to have this issue unresolved.
Regardless, I got a great deal on a new little lightweight C6 SCT I wanted as my larger Grab and Go scope for my CG-4 mount, since my C8 is too much weight for the CG-4.
First night I checked the scope looking at Jupiter and sure enough, as I moved the planet into the field of view, I saw the huge ring move into the field of view. As the planet got centered, the ring disappeared.
Instead of removing the corrector, I just removed the 4 screws that hold the entire front cell on the scope and everything just lifted off exposing the inside of the scope.
I had some black sticky back felt from a local fabric store and cut half inch strips 3.5" long and lined the front of the light baffle with it, leaving about 3/4 of an inch out so i could fold it over the front of the baffle. This entire process took about 5 minutes. I was careful to make sure each strip was agasint the other so the inside of the baffle had a smooth ring of felt material inside the tube.
Afterwards, I thought id flock the inside of the OTA since the scope was already opened and I had plenty of the sticky back felt left. I unscrewed the 4 screws holding the bottom of the tube to the lower cell and detached the body of the scope from the bottom cell. I cut 3 strips the full length of the tube and attached them in place. It was a quick process without having to worry about the primary mirror or light baffle in place.
After this, I put the scope back together. The tube had no wiggle installed all the screws so I was hoping it would maintain its collimation.
From start to finish, this took about an hr.
I put the scope on my mount and looked again at Jupiter. The diamond ring effect was completely gone and the collimation was dead on. I could see the GRS on the surface of Jupiter, despite the mediocre seeing conditions. I did a high power star test on Vega and the culmination was spot on.
Now I have a great little grab and go scope with 6" of aperture. Since I use my focal reducer on the scope, I have under 1000mm FL so i can go fairly wide using my 1.25" Explorer scientific eyepieces.
Too bad Celestron doesn't fix this problem. Many wont go through the trouble of fixing their C6's and just buy something different.
...Ralph in Sacramento.
Edited by aa6ww, 17 August 2019 - 06:40 PM.