I noticed some Galah's in the tree at the back of my house and thought I would hook up my Canon 7D to my Williams Optics Megrez 90 to see what the results where like. The results are bloody impressive in my opinion!
The following is a 100% crop:
http://www.flickr.com/photos/5640446...7626572115771/
Not an award winning shot, but I was impressed, because I normally use a Canon 400 f5.6 telephoto. I would say the Megrez is on par with the Canon in terms of sharpness, but slightly less contrasty. The Canon also handles colour correction better with backlit subjects.