Suppose I put one of my M lenses ( M 1.4 50 mm) is put on a digital reflex (looking at the K100D right now), with the aperture set to 8.0, is the diaphragm open or closed when the lens is mounted on the camera? How should I measure light? (aperture set to 1.4 ?, shutter speed manual only ?).

Just trying to find out if it is worth to use my primes on a digital reflex.