This should leave your lens looking like this. Note the center element screws in and out. This sets the focus range. Do Not adjust it until you're done. On the 50mm 1.4 you don't really have to take the lens apart to get at it. (When I was done I had to unscrew this element a lot to get the lens to focus to infinity. As it is currently set I could focus between 1-3 feet.)