Screw-in filter key for Super-8 cameras

Most Super-8 cameras have a facility to insert a 'filter key' which forces the camera to remove the filter from the light path.

This is used in the following situations:

• When using a higher quality external filter
• To use Daylight film where the camera doesn't automatically remove the filter
• To use Tungsten film under indoor (tungsten) lighting

This is the screw-in version that works for many models including most Canon, Minolta cameras.