I've been debating getting a Hyperstar for awhile, and decided to pull the trigger after reading a number of forums and looking at some images that have been taken from high Bortle number skies.
I wanted something semi-portable, so I bought a Hyperstar-6 V4 from Starizona and a new Celestron C6 OTA. In preparation for the set up, I watched a bunch of YouTube videos and read a bunch of CN articles on the Hyperstar and Hyperstar collimation - I have collimated a number of scopes and was not intimidated by that, but needless to say, there are quite a few articles about Hyperstar collimation and the troubles that people have had with it.
Note: I bought the Hyperstar-6 with the Starizona filter drawer to ensure that the backspacing would be correct (more on that later).
Here are the steps that I took:
1. Prior to receiving the Hyperstar, I 3D printed a tribahtinov mask (thanks Cuiv for pointing me to the STL file). I also 3D printed the cable router for the C6 (although that has limitations if you intend to use the excellent Celestron dew shield for the C6 (the two are not compatible from a fit perspective))
2. After I received the C6, I removed the secondary mirror and checked to see that primary was centered in the OTA. It was (whew!).
3. I did install a ZWO-EAF (thanks Buckeye Stargazer for the 3D printed adapter). I used a ASI1600MM-Pro main camera - that I know (from Sharpcap) has minimal/no sensor tilt issues. My mount was an AM5. Note: I did not install a filter in the filter drawer (and this will be an important part later).
3. I also checked that the scope was properly collimated - it was right out of the box. Not that this has a huge correlation to the Hyperstar - but, it was a double check that the primary was centered in the OTA.
4. Once I received the Hyperstar, I actually flattened it out. In other words, I used a gauge tool and ensured that the Hyperstar was .2 mm consistently from the back plate of the Hyperstar. I know that some people have put the Hyperstar flush against the back plate and have achieved good results with this method, but if the Hyperstar needs any type of adjustment tilt-wise, this leaves zero room for adjustment. I have to admit that I chose .2mm fairly randomly - as I wanted some room for tilt (microns is usually on the order of adjustment for the Hyperstar) - and I did not want to mess up the backfocus too much. I felt as if this was a good balance and it turned out to be correct.
5. I mounted the C6-Hyperstar on the AM5 - and ensured that I had a good polar alignment. And, I was off to the horse races. And...it was a frustrating night....sort of. I started with the Cuiv's (and other's) advice to decenter a star and achieve rough collimation by centering the Hyperstar shadow using the push-pull screws of the Hyperstar. Mission accomplished - BUT, when I looked at the stars out of the edge, they were terrible. After a few hours of tweaking (by the way, I was adjusting the push-pull screws by only 1/16 of a turn incrementally) I gave up for the night. I knew that I was close to collimation, but couldn't quite get there at the edge of the imaging chip.
I called Starizona yesterday morning - and they agreed that I was close and that it would require just a little bit of tweaking to get it right. Don't get me wrong, they were extremely helpful, but I had been doing that the night before with no luck. And then it dawned on me: I had no filter in the filter drawer. I purposely chose not to put a filter in the filter drawer just to minimize the variables of collimation. So, last night before I went out again to check collimation, I installed a Baader 2" UV/IR Cut filter into the filter drawer. As soon as I was focusing to start the polar alignment, I realized that collimation looked spot on. After I polar aligned the scope, I ran an autofocus and verified that the Hyperstar was collimated with the tribahtinov mask and CCD Inspector. Nailed it!
Perhaps I got lucky, but I wanted to pass on the fact that back focus is extremely critical at F2 - but, I presume that most of you know that already.
I hope that this experience helps you.
Edited by jmiller1001, 29 May 2024 - 11:02 PM.
