Orion Thin Off-Axis Guider puzzle

[04Stefan07 (Stefan)]

Ok my TOAG arrived and now I am trying to put it together. I have read the manual a few times and still bloody confused.

I have the Celestron focal reducer as well that I need to connect somehow.

Would anyone be able to help me or point me in the right direction?

Thank you!

[billdan (Bill)]

Hi Stefan,

If your focal reducer is threaded it should screw into the TOAG and the focal reducer is inserted into your focuser. Well that's how it works with a Baader MPC coma corrector.

Then you may need to use a spacer between the TOAG and the DSLR, to get the correct backfocus for the reducer. So get this bit working OK first so the reducer is working at optimum.

Then you position the prism in the TOAG so it does not create a shadow on the CCD chip in the DSLR.

Plug in your guide camera, focus on a star with the DSLR and then move the guide camera (in or out) until its focus point is the same as the DSLR.

Sounds easy but it can be frustrating to get it perfect.

EDIt: Be careful with the prism I had it fall out onto the grass once, took me ages to find it in the dark, and then I installed it back to front which took me another 30mins to figure out why I wasn't getting any picture from my guide cam.

Cheers
Bill

[tim.stephens (Tim)]

Another word of warning, be careful with all those little grub screws on the prism mount when adjusting. Don't do them up too tight and be sure not to drop any on the grass! Gone forever. There are quite a few on the front and sides to loosen when moving the prism.

Also, depending on your imaging weight,the finger tight screws on the side of the main OAG body may not be enough to hold your equipment in place. Just be careful that everything is orthogonal when assembling. I replaced mine with hex bolts and tighten firmly with a allen key.

[04Stefan07 (Stefan)]

Thanks for that! Much better described than the bloody manual!

That's the trouble I am having is attaching the focal reducer on. Maybe I need another type of adapter? Hard to tell.

Originally Posted by billdan

Hi Stefan,

If your focal reducer is threaded it should screw into the TOAG and the focal reducer is inserted into your focuser. Well that's how it works with a Baader MPC coma corrector.

Then you may need to use a spacer between the TOAG and the DSLR, to get the correct backfocus for the reducer. So get this bit working OK first so the reducer is working at optimum.

Then you position the prism in the TOAG so it does not create a shadow on the CCD chip in the DSLR.

Plug in your guide camera, focus on a star with the DSLR and then move the guide camera (in or out) until its focus point is the same as the DSLR.

Sounds easy but it can be frustrating to get it perfect.

EDIt: Be careful with the prism I had it fall out onto the grass once, took me ages to find it in the dark, and then I installed it back to front which took me another 30mins to figure out why I wasn't getting any picture from my guide cam.

Cheers
Bill

[04Stefan07 (Stefan)]

Good idea to replace them!

Originally Posted by tim.stephens

Another word of warning, be careful with all those little grub screws on the prism mount when adjusting. Don't do them up too tight and be sure not to drop any on the grass! Gone forever. There are quite a few on the front and sides to loosen when moving the prism.

Also, depending on your imaging weight,the finger tight screws on the side of the main OAG body may not be enough to hold your equipment in place. Just be careful that everything is orthogonal when assembling. I replaced mine with hex bolts and tighten firmly with a allen key.

[04Stefan07 (Stefan)]

OK all solved!

Called Bintel up and I think it was Don helped me over the phone on what I needed. I think he was putting a bunch of adapters together to with my current camera.

Needed an additional 2 adapters to make it work!

Will report how I go once I receive them.