A lux is the perpendicular incidence of a lumen on a surface of 1 square meter. Equivalent to 0.0929 lumens. When defining that a lux equals a lumen per square meter, it is specified that a lumen is equivalent to a candela x steradian. The total luminous flux of one candle source equals 4π lumens (since a sphere comprises 4π steradian). In short, it can be expressed that a lux is a derived unit, based on the lumen, which in turn is a derived unit based on the candela. It is used in photometry as a measure of light intensity, taking into account the different wavelengths according to the luminosity function, it is a standard model of the light sensitivity of the human eye.
Examples of lighting level.
|0,00005 lux||Light of a star (View from the ground).|
|0,0001 lux||Cloudy night sky, new moon.|
|0,001 lux||Clear night sky, new moon.|
|0,25 lux||Full moon on a clear night.|
|1 lux||Full moon at high altitude in tropical latitudes.|
|3 lux||Dark twilight boundary under a clear sky.|
|50 lux||Living room of a house.|
|80 lux||Hallway / bathroom.|
|400 lux||Well lit office.|
|400lux||Sunrise or sunset on a clear day.|
|1000lux||Typical lighting in a television studio.|
|32,000lux||Sunlight on an average day (min).|