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Well I managed to get down to the observatory for quick visit last night to do final collimation. I think that is achieved now, but will need a closer to focus test in better seeing. Perhaps the secondary is still a tweak out of circular. With the storm that has passed though in the last day or so the seeing has been fairly average, so it will have to wait.
I also now need to find out what the correct distance of the corrector should be. OOUK site says the correct distance is 79mm +/- 1mm from the lens to the sensor. The adapter that was made for me by them is 32mm screwed all the way down. The back focus of the QSI is 50.4mm from the T adapter to sensor, then I need to subtract 1mm for Astrodon filters and that equals 49.4mm. 79-49.4 = 29.6mm. At the suggestion of the manufacturer I moved the corrector further away by 4mm and took images. This has made things slightly worse general (although the centre is now sharp with the better collimation), which comes as no surprise. So I have ordered a new adapter from Precise Parts of 28mm. OOUK have supplied a locking ring which will help me set the correct distance I hope. I hope their information about the corrector is accurate. It's a $400 adapter.
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