Average Light Reflectance

• When you take a light reading of a scene to be photographed, the reading will show the average light reflectance of the scene. Within the scene to be photographed, there are different surfaces which reflect light to varying extents. When taking a light reading, the photographer attempts to measure a surface that reflects light to an average extent. For example the ocean and snow both reflect a large amount of the light falling on them, and coal or a black fireplace reflect little light. A mid tone is a surface that reflects 18 percent of the light falling on it--an average surface like a table top or bed spread might have a mid tone. It is a mid tone that the photographer must meter before taking a photograph. The photographer sets up the camera to interact with the amount of light reflected by the mid tone.
  
  

Identifying a Mid Tone

• The photographer must find a mid tone in the frame to be photographed--she must look for anything within the scene that is somewhere between shiny white and dull black. If there is no mid tone within the framed image then a light reading must be taken from an area outside of the framed image. The photographer will find a mid tone on his own clothing if necessary.
  
  

Average Light

• In addition to measuring average light reflectance, the photographer takes a light reading for the average amount of light. Average light is halfway between light and shadow. When it is sunny there is a big difference between the amount of light in the shadow and the amount in the light--this is not so much the case when it is overcast--however in both cases, the photographer takes a light reading.
  
  

Identifying Average Light

• When metering average light, the photographer finds a point in the framed image that is half in the sun and half in the shade and takes a reading. For example if metering a building, the photographer will point the light meter at the corner of the building, so the reading is being taken simultaneously from one wall in the sun and one wall in the shade. If the photographer is taking a light reading for a landscape photograph, she might use her own shadow. She will point the meter half upon her shadow and half upon the light, thus taking an average light reading.
  
  

Metering Indoors

• Taking a light reading indoors using window light is difficult because there is only a subtle difference between light and shadow. It is important to take an accurate reading in these situations because although the amount of light is low, the quality of the light is high, because it is defused and directed by the window.