80mm Guidescope #52309

Edit #1: I found the threading it says right on the product page - "M42 thread on extension tube" *slaps forehead*

Original post:

I have a Celestron 80mm Guidescope #52309 mounted on my C8. I've read that for astrophotography it's best if the camera is screwed onto the scope rather than connected via tubes with retaining screws (don't know the nomenclature offhand). I removed what I think is called the visual back from the focuser to remove it from the equation. The focuser silver tube has threads on it. They're not SCT thread as my corrector reducer doesn't fit (the diameter is smaller... maybe it was 1 3/4"? I'm at work and didn't bring in the measurements). Does anyone know what the threading is? Has anyone used this scope with a guide camera and or taken photos through it?

http://www.celestron.com/browse-shop/astronomy/astroimaging-accessories/guiders/80-mm-guidescope-package

Hello again. I wrote the first posts from work, in hindsight not the best idea since the scope wasn't with me. When I got home I looked again at the Celestron documentation and at the guide scope. I have a cheap caliper that I used to measure the various diameters. Celestron's site says their guide camera can connect to the scope via M42 threads. At first I assumed these were the threads on the focuser. Now I believe I was in error and that these are the threads on the extension tube.

I'm hoping to eliminate all possible flexure while still being able to focus. Here's a rough photo sketch of the three components. I'm seeking guidance with determining threads and thereafter the best adapter to a C-mount CCD camera.

I ordered an M42 to C-mount (subsequently cancelled before it shipped -- see below), after I thought I had it figured out, which [won't] work. The thing is I thought it might be preferable to go M44 (if the focuser is indeed M44) to M42 to C-mount or just M44 to C-mount... I believe from my rough measurement that the focuser has some sort of 44mm threads.

Edit #1: Could the focuser thread be Maksutov thread = M44.5 x 1.0 Female? http://agenaastro.com/blue-fireball-sct-thread-adapter-maksutov-cassegrain-telescope.html

:S

Edit #2: I found some information on determining threads. I measured again and the focuser seems ~44mm (I counted a few time and believe it was 5 threads in 5 mm). The extension tube was ~41.5mm threads (the threads seemed smaller... In my mind I made it 4 threads over 4mm however the Celestron site says, compatible with NexGuide and the manual for NexGuide says the scope must have M42x0.75. So I think my first perception of them being smaller seems consistent with that document.

I might have to delete this whole thread in hopes of not confusing anyone else who may search down the road. lol

Edit #3: I'm now thinking the Celestron 80mm guidescope focuser sports a Zeiss M44 thread. Anyone want to chime in?

Edit #4: If the threads are Zeiss M44 male on the focuser then it looks like my image train would be expensive:

Baader Zeiss M44 Female to T2 Female Adapter # T2-09 1508041
Blue Fireball Gender Changer: T / T2 Male-Male Thread Adapter # G-TM
Baader Male C-Mount to Female T / T2 Adapter # C-T2 2958520

The Baader male c-mount to female t2 is nice in that it accepts 1.25" filters

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