1. In the UK, illuminances are reduced with higher values S / P ratio 2. An illuminance of 6400 8600 high pressure sodium, and metal halide lamps. 3. Illuminance is a measure of how much luminous flux is spread over a given area.4. Two national standards now allow for variation in illuminance when using lamps of different spectra. 5. At EV = 15 ( the " sunny sixteen " amount of light ) the illuminance is or. 6. In radiometry, radiosity, luminance, luminous flux, luminous intensity, illuminance , luminous emittance ). 7. The luminance range of a scene maps to the focal-plane illuminance and gamma of the film. 8. for example, air temperature in the case of space-heating or lux levels for illuminance . 9. For a given spectral distribution, the photocurrent is linearly proportional to the illuminance ( and to the irradiance ). 10. In astronomy, apparent magnitude is a measure of the illuminance of a star on the Earth's atmosphere.