CAA Rotator and ZWO OAG

lausso

I recently ordered a CAA, which should arrive end of the month, and I would like to have the following image train on my 9.25HD:

Camera -> Filter wheel -> CAA -> OAG-L -> Telescope

However, I am not sure how to connect the CAA to the OAG.

The CAA has a M54 female thread at the telescope side and the the OAG also has a M54 female thread on the camera side. However, it's not possible to use a M54 male/male thread to connect them as the "belly" of the rotator blocks screwing rotation to each other. Not sure if I explain myself well enough, but I hope you get the idea.

Tech@ZWO

lausso If you do not have a back focus length requirement, you can connect the CAA after the OAG-L and add a M54 male-M54 female adapter between them to solve this problem.

lausso

Tech@ZWO Yes, that's an option too, but it would require re-calibrating after each rotation...

crackout

Tech@ZWO

Are there images of a mounted CAA-OAG-L-EFW combo?
It seems to me that the protrusion of the helical focuser collides with the CAA.

Tech@ZWO

lausso Are you referring to guide calibration data? if so you can check the rotate guide calibration data with CAA option in the settings.

Tech@ZWO

crackout Yes, need to add a adapter betwen the oag and CAA.

crackout

Then that makes it unusable for me, I only have 16mm left without the CAA.
OAG-L, EFW and camera already take 55mm.

Larry.Cable

I dont see how it is possible to combine an OAG with a CAA and achieve 55mm back focus.

an OAG cannot go "behind" the CAA since the OAG would collide with the body of the CAA when rotating through
certain angles.

Therefore the OAG can only go in "front" of the CAA, between it and the scope, but again it must be possible
to attach the OAG to the CAA with the OAG body clearing the CAA case.

this would require a suitable adapter (with little or no additional incease in total back focus) to connect the two components...

evltoy

Hi All,
I have managed to setup my OAG with the CAA on my C8.

C8 -> .63 reducer -> Celestron Radial OAG -> CAA -> EFWmini -> 294MCpro

With the .63 reducer I have 105mm back focus to play with. The OAG is 50mm and I had to buy adaptors with 1-2mm thickness. When I plate solve I'm at 1275mm. This was not cheap, but what is in the world or astro imaging.

My only issue is I cant rotate a full 360 due to the EFW will hit the connectors on the EAF. I'm waiting for ZWO to provide a solution where we can set a dead zone to prevent this from happening.

you can see my setup here.
https://www.instagram.com/p/DIGFQh3SONA/?igsh=cmVoMTkwNDZ1eGRj

Sctom

How do you avoid the shadow of the OAG prism on your camera at some angles with this set up? I have always seen the set up in this order Scope>rotator>OAG>EFW>camera. This way the OAG stays fixed relative to one of the long edges of the camera so the prism never cuts into the camera image.

evltoy

Sctom On my OAG, I can manually adjust the prism to be pulled in or out depending on which side it's positioned relative to the camera sensor. This is a manual process, so when I'm working with multiple targets, I set the prism accordingly.

The key advantage of this setup is efficiency—I don’t have to recalibrate the OAG every time I reposition the camera sensor during the night.

Note: When capturing flats, I always record the rotator values and return to those exact values when working with multiple targets.

OGcGN11P

This is how I managed to get the full 55mm backspacing while still using the OAG. The coma corrector goes all the way through the CAA, so it doesn’t add any extra length — it sits right up against the OAG. I did have to make a custom spacer for the OAG though, to extend the mirror tube a bit so it wouldn’t hit the CAA. For now it’s 3D printed, but I’ll probably get it made from aluminum later on.

Image train setup:

Skywatcher Quattro 250P drawtube

M54x1.0 male to M54x0.75 male adapter (3D printed just to test the fit and make sure the coma corrector still clears — it’s a really tight fit)

The adapter screws into the CAA body (M54x0.75 female)

The coma corrector screws into the M48 ID on the rotator plate of the CAA

The outer M54 male threads from the CAA go into the OAG

The Player-One OAG, filter wheel, and camera all use the same 6-bolt pattern, but they’ve also got M54/M48 threads