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Hi, Greg, yes it was the development of quite severe slop in the super-strong Hederick focuser. Was good out of the box. Possibly got too tight over winter and bent the casting. Our total load of camera, off-axis guider, and guide camera are within weight spec, and it's normally racked almost all the way in, so that should have helped. It flopped enough to produce severe camera tilt, and severe change of focus, as we tracked in RA. Could just order a new one I suppose, except it would probably just do it again.
Will take a photo of our stiffening apparatus and post it. It permits say +/- 5 mm of focus movement, but stops the camera from flopping about in RA.
That's a bummer. Careful about removing the focuser as its shimmed to make it square. They didn't tell me that and the shims fell out. I put them back where I thought they were and everything seems fine.
I looked at this image in CCDInspector and it says there is quite a bit of tilt and collimation is off 3.1 arc seconds (not much). I don't know how much to believe CCDInspector although I noticed it can occasionally give inconsistent readings but its a guide.
At your focal length I would recommend a large Tpoint model and use the Protrack corrections if you are able to. I find it can take stars just that bit more to round.
Also try an infrared 750nm 25mm filter in front of your guide camera. Sometimes the guide stars are not bright enough but other times they are and I think that can help sometimes as well.
Greg.
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