I got one of those really cheap Chinese lens adapters for $17 (the "Fotasy" brand) to use with the venerable Canon FD 50mm f1.4. It works great for my purposes and for most applications I have no complains. But I discovered I wasn't able to focus to infinity when I pointed the camera at some clouds. I read that the problem is caused by the adapter not providing the exact distance from the lens to the sensor. My adapter is apparently a bit longer because the focus does not reach infinity. Other people report that they can focus "beyond" infinity suggesting their adapter is shorter. I took mine apart and sanded it down a bit. I was pleasantly surprised to see that I was able to focus at further objects. I was also surprised to discover my whole adapter is made of aluminum rather than plastic as it appears. If your lens is able to focus beyond infinity maybe you can try to add a very thin spacer on your adapter to increase the distance. Does anyone know a test I can do to find out if my adapted lens focuses exactly at infinity.