The unit of illumination when the foot is taken as the unit of length. It is the illumination on a surface one square foot in area on which there is a uniformly distributed flux of one lumen or the illumination produced on a surface all points of which are at a distance of one foot from a point source of one candela.
A unit of measurement indicating how much illumination is reaching a surface.
A unit of illuminates, incident light, or illumination equal to 1 lumen per square foot. This is the illuminants provided by a light source of one candle at a distance of 1 foot, hence the name.