Has anyone done any testing of this reducer on medium focal length refractors? I'm specifically interested in flatness and astigmatism when coupled to a refractor such as my Megrez 90 (90mm f/6.9 FD). I know Avandonk has one of these, but isn't primarily using it on a refractor. Hopefully a few other people have run into some information on these, as Google seems a bit sparse on information.
The 5D/101ED image at the bottom of this page looks promising:
http://www.sciencecenter.net/hutech/.../html/7887.htm
as do the spot sizes in the graphs.
This being a significantly more expensive flattener than the one that I currently have, I thought I would ask around before picking one up
Regards,
Eric