Is my Atik OAG faulty?

[rkc]

I recently bought an Atik OAG and Lodestar C, but I'm struggling to get them set up properly. May well be user error, but one of the issues I'm seeing is that the image on the Lodestar (when mounted on the OAG is severely vignetted by the tube coming from the prism. When I look at the OAG with no camera mounted, in order to see clearly up the tube through the prism I need to move my head well off the telescope axis.

This suggests to me that the prism angle is wrong, but there seems to be no way to adjust this on the Atik OAG. Can anyone with an Atik AOG confirm that the prism should be set so that looking directly down the telescope axis you can see straight up the tube to the guide camera?

[Davey-T]

Not quite sure what you mean, what scope have you got it on ? I've got mine on  SCT so can't really look straight down the scope, the prism is only held in place by a small plastic screw and when I was first fitting mine the prism actually fell out so I guess it could be out of alignment but seeing down the tube and out through the guide camera hole sounds right. How have you got the camera mounted ? my Loadstar needed a pile of spacers to achieve focus, also a lot of faffing about raising and lowering the prism to get it in the right place.

Dave

[rkc]

Not quite sure what you mean, what scope have you got it on ? I've got mine on  SCT so can't really look straight down the scope, the prism is only held in place by a small plastic screw and when I was first fitting mine the prism actually fell out so I guess it could be out of alignment but seeing down the tube and out through the guide camera hole sounds right. How have you got the camera mounted ? my Loadstar needed a pile of spacers to achieve focus, also a lot of faffing about raising and lowering the prism to get it in the right place.

Dave

It was attached to an ED80 when I observed the vignetting, but I removed it from the scope to observe the alignment issues - I was just looking into the OAG tube from the axis of where the scope would have been (if that makes any more sense).

I found the small plastic grub screw, but even when removed the prism appears to be firmly glued into (incorrect?) position.

[Davey-T]

It was attached to an ED80 when I observed the vignetting, but I removed it from the scope to observe the alignment issues - I was just looking into the OAG tube from the axis of where the scope would have been (if that makes any more sense).

I found the small plastic grub screw, but even when removed the prism appears to be firmly glued into (incorrect?) position.

Mine was only held by the screw, didn't see any glue.

Dave

[rkc]

Mine was only held by the screw, didn't see any glue.

Dave

Even with the screw removed completely, the prism seemed pretty firmly fixed - not sure if actually glued or just very tightly wedged. However with a great deal of force I was able to shift it slightly, and it is now much better aligned (and the vignetting - while still present, is greatly reduced.

I was able to successfully guide last night for the first time, so I think I'll stop worrying now.