SLR camera with focal plane shutter - has aperture returned to fully open for easy focus check after exposure

摘要

The SLR camera with an adjustable between-the-lens shutter and a focal plane shutter has an additional stop on the shutter speed range. This is used in conjunction with the focal plane shutter and ensures that the aperture elements are returned to the fully open position for focussing clarity after exposure, and not closed. The special setting operates a blocking lever which inhibits the closing movement of the aperture drive, but which allows the drive to move the elements into the fully open position. A cam moves the aperture closing lever into an inoperative setting.