> -----Original Message----- > From: Tim Sherburne [mailto:[EMAIL PROTECTED] > > > Okay, Anthony, I confess! I've been on this list for a good bit, but I've > never heard of anyone mentioning "viewfinder registration" before. Perhaps > my memory is failing me. Please enlighten me! >
Tim, The film plane, the lens mount, the focusing screen and the reflex mirror are all mounted on the mirror box and need to be accurately aligned to each other. Misalignment of each of these has its own particular symptoms. The most frequently discussed problem has been compaction of the mirror rests in LXen, causing infinity focusing errors and 'sticky mirror syndrome'. The film plane and lens mount are most liable to get disturbed by physical shock to the camera, eg. dropping. As well, the lens mount is vulnerable to cumulative stress from eg. a heavy unsupported lens. While the focusing screen is also vulnerable to physical shock, in my case I believe the misalignment in a Super A and an ME-Super was caused by 'creeping' of the set screws around the screens' frames, because the problem arose suddenly and was first noticed soon after several plane trips on which these cameras accompanied me. This was after several earthbound years of faultless service. There has been anecdotal evidence through the years that high frequency vibrations in jets can unwind the fine screws in cameras. One case that is surely an urban myth is of the photographer whose Nikon F jettisoned the top half of its photomic finder in an airport arrival hall after a long flight. It apparently happened to a friend, or a work colleague, of almost every photographer I met in the 1970s and '80s (hence my urban myth suspicion). regards, Anthony Farr
