Some time ago I was lamenting that I had missed some articles posted by Peter John Smith. Peter was nice enough to do an ADC/corrected Dall design for me using LISMs, which I have never built.
Anyway, he had articles on several topics including field correctors. I have copies for some but am missing the prime focus for parabolic mirrors write up.
Well, I finally looked in the right place, the "wayback machine" did in fact capture the site---here it is...
2/2002 has most of the good stuff
Edited by gregj888, 15 February 2020 - 12:23 AM.