OAG and Moonlite Focuser

[Benny L (Ben)]

Hi All

I find myself in a bit of a spot I have a meade 14in LX200R sitting on the back of a losmandy titan. Piggy-backed onto the 14in I have a 5.5in Celestron Maksutov as my guide scope.

My arc-sec per pixel is relatively close. I am using a SBIG STL-11K with remote head for guiding. 0.52 arc-sec through the 14" compared to 0.76 arc-sec through the guide scope.

When I actually manage to find a guide star through the celestron it guides away quite happily with maximum errors of about 1.2px + or - of 0, without PEC. However when i come back to see what i have manage to get the stars through the main scope are egg-shaped. My conclusion is differential flexure

Enough with my life story

I am looking at getting an OAG and am wondering what my options are seeing as I have a Moonlite focuser hanging off the back of the 14". Are there adapters to fit something like the Astrodon MOAG onto the moonlite and in turn mount that to the focuser?

Any info would be much appreciated

Ben

[Benny L (Ben)]

Anyone??

[el_draco (Rom)]

I'd go for the Astrodon MOAG. I researched this a lot and they are serious heavy duty hardware with demanding tolerances... but they come at a price... big one. I'll get one myself eventually.

[Bassnut (Fred)]

Yes, MOAG is the only way with the ST11k load. There are a heap of adaptors available. OPTEC alone have pages of adaptors, even though they dont sell the MOAG. The ST11k/MOAG is a common combo. I bet Moonlight, SBIG and Astrodon between them would provide the answer.

[allan gould]

Ben
How Are you attaching the guidescope to the 14 inch scope? I'm using a 90mm mak to guide a 10"SCT and find no problems. To eliminate flexture the guidescope is attached to the main scope using a Losmandy rail and losmandy attatchment plate to which the guidescope os rigidly bolted. No flex that I can detect. Just a thought for what it's worth as I don't like OAGs.

[Benny L (Ben)]

Hi Allan,

I attached the Mak to the telescope via a losmandy dovetail. the mak has one of those celestron dovetail thingos which i can't take off because the screws that hold it on have nuts on the inside of the tube.

So i have attached it via 2 losmandy camera mounts as it has holes for attaching a tripod. Normally I'd use tube rings but my losmandy rings are too small to fit over the scope and celestron dovetail.

in any case my dad has just bought a milling machine so i'll have a crack at making my own rings that are big enough to fit. Failing that I have asked moonlite to make me a custom focuser which will allow me to thread the camera directly to it. which is why i was asking about OAG's as i would make/buy adapters to thread each directly to minimize flexure

[allan gould]

Ben
If your dad has a milling machine may I suggest he knock you up an x/y shifter. I can send you photos of one I had made up and since the 90 mm
mak is solidly bolted to the main scope via the losmandy rail, I use the x/y finder and a parfocal eyepiece to find and centre a guidestar. Very quick, easy and fool proof. And no flexing. Rings I find are almost certain to give flex between the main scope and guider as the mount tracks. Others may disagree but that's been my experience. At the moment I can easily photograph at 2500 mm fl using a dsi ii pro cammera and that's normally tough to do due to the magnification.

[el_draco (Rom)]

Originally Posted by allan gould

Ben
If your dad has a milling machine may I suggest he knock you up an x/y shifter. I can send you photos of one I had made up and since the 90 mm
mak is solidly bolted to the main scope via the losmandy rail, I use the x/y finder and a parfocal eyepiece to find and centre a guidestar. Very quick, easy and fool proof. And no flexing. Rings I find are almost certain to give flex between the main scope and guider as the mount tracks. Others may disagree but that's been my experience. At the moment I can easily photograph at 2500 mm fl using a dsi ii pro cammera and that's normally tough to do due to the magnification.

I have my guidescope locked down solid as well and use the Orion X-Y Guidestar finder to adjust my guidecamera position. Very effective. It also does eliminate one source of flexure quite well.