Thanks, yes very pleased with how this worked out, particularly with an ED80 at f/7.5. I just wish I could get the collimation on my SN-8 sorted out once and for all. The secondary keeps moving (rotating in the corrector). I think the result on M42 would be even better with 8" of f/4 aperture but maybe not. Anyhow, having the SN-8 out of action again is such a pain... For me collimating the secondary on the Schmidt Newt is like having a tooth pulled... It's absolutely trial and error for me to fix this again.
Ho hum...