It's not as easy as that Greg, using the PL16803 with the AP (which had a big flattener about the same distance from the CCD/CCD window 86mm v 78mm) the L and Ha filter showed almost no halo but the RGB all did, with the AG12 and PL16803 it appears the RGB and L give very little halo but the Ha shows the small solid halos. I got similar small halos with the Ha filter and PL11002 with the Starfire, so it is not as easy as it looks to tell who the real culprit is...?
The Orion corrector is ED glass, fully coated and the elements have blankened edges.
In the end, as Peter Ward says, optical diffraction effects are sometimes just trade offs for other capabilities I guess..? Having said that there may still be the ability to mitigate the effect...soooo you know anyone with a set of Astrodon genII 50 X 50 filters I could borrow for a little while to test the theory...
:prey :
Mike