#exposure.light_unit  the intensity of light falling on a photographic film or plate; "he used the wrong exposure"
  supertype:  #light_unit__lightunit  a measure of the visible electromagnetic radiation
  subtype:  #overexposure.exposure  exposure to too much light or for too long a time
  subtype:  #underexposure.exposure  exposure to too little light or for too short a time

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