I have had a couple pairs of Steiner's that you individualy focus each eye peice once and then leave it alone. They have no center focus nob. They worked fine. They just are not high quality glass. My swarovski's once I got the left eye piece set (it took about a month to find the right spot). I have never had to touch the center nob. It doesn't matter if I look at 10 yards or 10 miles they are always in focus.