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Gooday George,
I think it will be close, it all depends on how far forward the M48 adapter is from the CCD chip.
e.g if the M48 adapter is at a 42mm distance from the CCD chip the on-axis light cone is 42mm/FR or 42/7 = 6mm diam, but you have to add the diagonal size of the CCD chip (in your case 45mm) to get 100% illumination at the corners.
So at 42mm distance your tube diam needs to be 51mm wide or vignetting will happen.. At a 21mm distance it is 48mm and you would be OK.
I would think for the 80mm APO and that size chip a 3 inch focuser would be necessary.
Hope this helps
Regards
Bill
Last edited by billdan; 22-03-2016 at 01:10 PM.
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