[allan gould]

I recently purchased an Orion off axis guider to use with my 10" SCT and QHY8 camera. I must admit that I was not impressed with the quality of the OAG as the parts are not machined tightly enough and there is slop between all major parts despite the use of two screws to tighten every thing up. But after taking each aspect one at a time I finally managed to shim each moving part so that it was rigid enough to use for guiding.
As a test object I used Eta Carina as there would be enough background stars for the OAG to see and I could get a lock on. I used PhDguiding with 2 second integrations with my DSI II camera as a guide camera through the OAG. Shifting the prism with the small screw is possible but it winds up shifting the plane of focus as well so that stars outside of that plane are seagulls.
Anyway I had done 5 and 10 minute integrations with the OAG and QHY8 so I wondered how far I could push it, so I tried 20 and 30 minute shots with the qhy8. Ive attached an unprocessed shot of the whole field of the 30 minute shot and a 400x enlargement of the region around Eta Carina. Stars are really sharp and symetrical and I was very happy with the low noise in the shot as well as the tracking. However it looks like the OAG causes some vignetting, but thats easily removed with a flat field.