OPT Triad Ultra Filter
I’ve been lucky enough to test the OPT Triad filter (Radian Telescopes) for astrophotography in the backyard. This is a 2″ quad-band narrowband filter that collects light in 4 bandpasses, Ha, OIII, SII, and H-Beta. The “Ultra” version of the filter improves upon the previous tri-band version, now with an even narrower band-passes, and the…