Hi all - we've bought a new camera to go with existing telescopes, and it turns out the included adapter package does not work for our telescopes. I'd like to get some advice before we buy more things.
Telescope: Celestron C-8 8" Schmidt-Cassegrain
Camera: QHY268M plus CFW3L
The camera and filter wheel came with a basic T-adapter (M54 male to M48 female??) and a back-focal length set that has M48 and M54 options (QHY does not supply a thread count/pitch that I can find). Based on this article the Celestron rear cell has a male 2"-24 threads/inch connector.
I think what I need is a SCT 2"-24 female to M48 (or M54) male adapter. Like this blue fireball one. Is that correct?
If I just get that adapter, I feel like attaching the camera will be miserable because I'll have to turn the whole thing to get it to attach. The generic Celestron SCT T-adapter has a loose ring at the female end so that you can hold the adapter still and just screw the ring to tighten everything. What is that particular type of adapter called? Does anyone know of a good one that connects a SCT 2" to M48 (or M54)?
(QHY's help desk says I need a "M48 male to 1.25″ lens barrel", but that seems to imply using the existing visual back with this other adapter and then the CFW with its adapter. Which seems like more parts than necessary, and possibly unstable.)
Look in ScopeStuff. I think they call this a T adapter with "collar ring". Especially look here for details and pictures: https://scopestuff.com/ss_tadpt.htm . If SS doesn't have exactly what you need Precise Parts can probably make it for you. I have received good advice from both these sources for this kind of problem. Precise Parts may already have the design on file.
Phil
The clear aperture leaving the C8 is only about 38mm so there isn't much to be gained by an M48 connection vs. M42 which is why the available T-adapters for a C8 are all SCT thread to M42. So you could use a standard T-adapter and add a M42-M48 adapter to connect to your CFW's M48 adapters, or don't use a T-adapter and go with the Blue FireBall one you linked to. But then the camera orientation relative to the scope is fixed. Not sure if you're also using a focal reducer or OAG, but a reducer will have backfocus implications meaning you'll have to add extensions to get you close to the optimal value. In my previous setup, my OAG (Hercules) had rotation adjustments on either side so acted like a rotator, but in your case you could consider adding a manual rotator for that adjustment. But for ease of setup which was your original concern, your options are a bit limited. Personally I don't think screwing on the camera+FW instead of the T-adapter collar is a big issue but that's personal preference.
Keith
They did a similar job for me. I couldn't remember the company name;
https://www.preciseparts.com/ppmain//index.html