Without knowing (seeing) where the shims were, it's hard to say. I'll assume the focussing screen is fixed and not shimmed. You need to place the mount flange surface a specific distance from the filmplane as well as perfectly square to the film plane. I'd use a surface plate, gauge blocks or precision parallels to rest the camera on, and a good dial indicator reading to .0001". Focus would be checked by viewing the aerial image at the plane,(both film and GG) not on groundglass. Next time record where the shims were and replace them precisely as they were.
Originally Posted by Yashinoff