Metering systems

1. traditional metering inside a camera without electric or electronic exposure control

A selenium cell and an electromechanical instrument are combined. A glass plate with multilens surface bundles light onto the cell. The instrument, the meter, shows with its needle a) a number, or b) its needle moves around a single mark.

  • a) A simple analog calculator will help to find an appropriate shutter-speed/aperture combination manually. The ASA speed of the film must be preselected on the calculation slice, then the number given by the meter transferred to that slice. In cases were the meter doesn't give a number the calculation wheel may be positioned over the meter. In such a case a mark on the calculation slice has to be moved towards the needle until mark and needle match. Then all combinations of shutter speed and aperture shown on the calculation slice can be selected for correct exposure.
  • b) In this case the meter is coupled with the ASA preselector, the aperture selector and the shutter speed selector. The ASA speed must be selected according to the speed of the actual film in the camera. If the meter's needle matches the mark the combination of selections is appropriate.