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Old 18-03-2013, 11:10 PM
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Andy01 (Andy)
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Andy01 is offline
Join Date: Mar 2012
Location: Melbourne
Posts: 2,349
ED120 & SBIG focus problems

Hi folks,

Still a bit if a newbie at this and wondered if any of you could help me with some advice.

I have a Saxon ED120 7.5 refractor (same as Skywatcher) and an SBIG 8300c
OSC recently purchased 2nd hand here on IIS.

I tried testing it, and there's an image there, but it won't come into focus.
The camera has a 2" nosepiece, which fits nicely into the OTA.
But the preview image on Nebulosity is out of focus even at maximum extension. Looks like the camera needs to travel backwards another couple of inches past the max back focus available on the standard crayford unit supplied with my scope.

As a workaround, I tried inserting the camera nosepiece into my diagonal, which almost achieved focus the other way at minimum extension, but the image needed less extension than is available, go figure : )

How do I get around this please? Any helpful advice and suggestions appreciated.

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