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OAG - finding a guide star/ Focus
Looking at the photo one thing stands out.. I need at least a 2" extension between the OAG and the guide eyepiece/ camera.
I use a prism diagonal in this section to minimise the distance ( over hang)
(Must be a prism type not the mirror type - to reduce the optical path length)
This should get you into a focussed guide star image.
To get the set-up "tuned" the easiest way is to position the OAG pick off prism in the RA direction. That way, when you position a bright star you can allow it to drift in RA until it hits the prism, makes it much easier to check things out.
Light train SCT -> Meade Motorfocuser -> OAG -> T ring + DSLR .
Guide: -> 2" extension ( and /or prism diagonal) -> Meade DSI.
I assume the diagonal you mentioned in the image train was for visual checking only!
Last edited by Merlin66; 26-04-2008 at 12:41 AM.
Reason: added comment on OAG prism
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