Thanks for that Paul, a very helpful and intelligent reply. I hadn’t quite looked at it in that light (pun not intended!) as I’m just a bit wary of anything of shorter f/ratio than F/11 on a 2 element refractor. Ideally it would be great to test them side by side, but that would be a rare luxury! I do like deep sky, and the skies around my way are fairly dark. However, I always feel that refractors excel on planetary objects, but not so on the faint fuzzies!