Makes no difference where you use the Baader MPCC, its alwas 55mm from last optical surface.
Even still, if out by a bit, viewing, its still makes points of light to stars on the edge. I had it on my 22" f4.5 with great results.
Both good choices, but the Parracor adds to the f ratio, wheras the Baader is at x1.
Theo
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