Thanks all for the comments
Ken, no I didn't change the spacing, just spent more time with the focusing. It seems by getting the focus just right the stars around the edges improve, they are by no means spot on, but its certainly better than my previous attempts with the WO flattener. Honestly, I should just let go of the ED80 and get myself a FSQ-106 as a replacement
Mike, Yep I agree, I should have shifted the frame across just a touch to include the cluster. With a 480mm FL and a 350D sensor, it should all
just squish into the frame
Michael