I have an old Canon 50mm 1.8 lens with m39 threads I have been wanting to use on my 5d mk ii. I got an m39 to eos adapter and all seems to fit well on the 5d except I can not focus the lens. Focus on the lens ring from 1m to infinity are just a blur. I use other manual focus lenses with out a problem so surprised at this failure. Any help is appreciated.