COMMONLY USED PROJECTION SCREEN TERMS
A foot-candle is equivalent to one lumen per square foot (where a lumen is a measure of the luminous flux, or quantity of light).
A wax candle flame has a luminous intensity (or equivalently, candlepower) of approximately one candela. If you hold the candle one foot away from a surface, the illuminance of the surface at this distance due to the light from the candle will be approximately one foot-candle. It will be 1/4 fc at two feet, 1/9 fc at three feet, and so on in accordance with the inverse square law for point light sources.