I defy anyone to say with certainty which filter brand will work best for Berts new system. Without a thorough reflection and band pass analysis you simply can't, it is all plain and simple guess work based on anecdotal evidence. Astrodon Gen II, Baader,
latest low reflection Astronomik, none of you know for certain which will provide the best results.
Bert, all these are good filters and all have been involved with systems producing halos or reflections of some sort with one system or another.
I have used the latest generation Astronomiks on a slow (F8) APO refractor with 2 element 4" flattener and I have also used them on a fast (F3.8) Newt with 4 element Wynn corrector and the results a very different.....and you have an exotic F3 mirrored system on its way...The Astronomiks are good to about F2.8 I believe but drop a line to Gerd Neumann:
info@gerdneumann.net
Regardless, in my case, both systems have returned award winning images - so don't get too hung up about'em, as far as halos your guess is as good as anyone's Bert, the fast F3 is the issue here and the responses you get from the various manufacturers in this regard may be very interesting
Mike