Thanks for the "insta guide". I've got a BBC and two "New"s waiting to be tried out on the A77 that I just got. I will take one of them to a college football game next weekend, but I need to figure out how to get them micro adjusted on the A77 first. Does one perform the back focus test with the lens at 300mm or at 75mm? I realize the A77 will not know the difference between the two "New" lenses, but what about between the BBC and the New?