My personal imaging setup is an SV70T + 0.8X FF/FR on a Sirius EQ-G mount.
But I occasionally use our club's old 6" f/8 AP triplet for imaging. It is one of Astrophysics' pre-Starfire triplets, and has color correction roughly comparable to a 6" f/20 FH doublet.
So when I image with the 6" f/8 AP, I get some noticeable blue/purple haloes around the brightest stars in my subs, even though it's color-corrected enough that I can't see them on any stars dimmer than 1st magnitude.
Question--what's the best way to minimize/eliminate the blue haloes in PixInsight?