Angle of Reading

Both forms of  hand held Light meter are designed to measure light within approximately the same angle of view as a normal camera lens, about 46 degrees. It pays to remember this when using either of these light meters because the meter reading can easily be fooled by the subject tones. In many  cases a more accurate reading is obtained by taking the reading from an essential part of the subject. The meter is taking all the tonal values in the view that it is reading and averaging them out. It then assumes that the average of these tones would be recorded on the film as a mid tone of gray. 

In subject like case the meter could be fooled by the dominance of the white background meaning that the image could be under exposed. 
 

In subject like case again the meter could be fooled by the dominance of the darker background meaning that the image could be over exposed. However taking  reading where the meter is reading from the skin tone would give a more accurate exposure reading. Remember that a caucasian skin tone is about 1 stop brighter than the mid gray a meter would read. 

 

A supplementary light diffusing dome fits over the cell for incident light readings, which are readings from the light rather than the subject.