Why is there play on the knob of my FocusONE? Is something wrong? Ashley July 26, 2018 20:33 The play on the knob is within the standards of the FocusONE! Please see the video below for further explanation: Related articles FocusONE How do I fine-tune the Focus Module? How do I operate the FocusONE? How do I assemble the Focus Module? Why are focus by wire lenses not compatible with the Focus Module? Comments 0 comments Please sign in to leave a comment.