a unit in which to measure light visible
to the human eye
cell meters, when filtered, are often used to measure footcandles. i never heard of a footcandle
before i came to miner institute
; i suppose they are most commonly used among scientists
. here we use them all the time to measure the light levels in the cow
story: in the early 40's, companies like general electric
came out with meters that supposedly measured black light
in footcandles. however, since footcandles are only a measurement of visible light, we can see this as a scientific inaccuracy
put up with for the sake of convenience.
http://www.magwerks.com/Information/footcandles_vs_mW.htm really knows its footcandles...