If u are ok w/ taking the front section apart, it is pretty easy to shim most of these adapters. Just got to watch out for the spring mechanism for the lens latch.
Depending on how far off it is from infinity, anything from common aluminum foil to thin brass shim stuck u can find at hardware store like OSH, will do. Just cut some to basic shape of the ring, does not have to be perfect. Try and error, until u get infinity focus correct. Depending on the foal length of the lens depends on how far away u need to focus, but a min. Of about half mile should be ok. I use a electric power grid tower which is about 5 to 8 miles away from my home for anything over 50mm. Probably over kill.
Gary