You get the rubber off by sliding a thin piece of flexible plastic under it, a piece of 4x5 sheet film works perfectly. Slide it around all the way to break any glue bond and then slide the rubber sleeve off the front. That lens in a pre AI one according to the serial number, and likely has the factory conversion aperture ring on it. Check for loose screws in the lens mount.
Edit: I suspect he is using a digital body.
If you are using one and focusing manually, the viewfinders on AF type cameras are not meant for manual/visual focusing. You are looking at an aerial image, not one focused on a ground glass. If the diopter setting on the camera is off, or if your vision is not 20/20, or if you have young eyes(under 40+), your eyes can easily focus on the wrong image plane in the viewfinder, and that will make the recorded image out of focus.
Last edited by Bob-D659; 07-28-2011 at 11:56 PM. Click to view previous post history.