I know this isn't the ideal setup but I have access to a good selection of Minolta glass so I can try it without any expense.
I've got a Canon 600D, a "Minolta Sony Alpha AF Mount Lens to Canon EOS EF mount adapter" and some Minolta lenses, including the 70-210mm f/4.
With the recent blood moon I mounted the 70-210 on my 600D to try and get some half decent shots. The movement of the moon was one thing but mainly my focus at infinity was useless. I thought it was maybe at infinity slightly back from the stop, but that produced worse results. I then tested at a building ~70-100m away from me in the day time, but it was still very soft.
This was all with a tripod and remote trigger so I don't believe it to be a stability issue. Similarly, my manual focusing skill are poor but I can get it pretty sharp when I'm focusing on near field objects so this does seem to be an infinity focus issue.
Can anyone confirm if this is a register distance issue?