The eyepiece focal lenght on the PVS-7 or PVS-14 type eyepeices is about 27mm.
A 50mm lens would give you slightly less than 2x.
Do you have a 3x Afocal lens? I am curious tho know if stars are any sharper in modern zooms than the are in my older zooms. Even with heavy filters, I still can't get stars to be particularly sharp. I don't think these older zooms had very good light transmission and perhaps bloat a bit becuase of internal reflections, but that is just a guess.
I had always figured a true Apo lens or ED lens would give a result that would be similar to the Afocal lenses, though at a very high cost. These lenses get pretty pricey when they get big and fast. I was kind of curious to know how these later lenses, which often use some ED glass, would compare.
Edited by Eddgie, 07 September 2016 - 10:26 AM.