As visual perception varies logarithmically, it is helpful to have an appreciation of both illuminance and luminance by orders of magnitude.
Illuminance
editTo help compare different orders of magnitude, the following list describes various source in lux, which is a lumen per square metre.
| Factor (lux) |
Multiple | Value | Item |
|---|---|---|---|
| 0 | 0 lux | 0 lux | Absolute darkness |
| 10−4 | 100 microlux | 100 microlux | Starlight overcast moonless night sky[1] |
| 140 microlux | Venus at brightest[1] | ||
| 200 microlux | Starlight clear moonless night sky excluding airglow[1] | ||
| 10−3 | 1 millilux | 2 millilux | Starlight clear moonless night sky including airglow[1] |
| 10−2 | 1 centilux | 1 centilux | Quarter Moon |
| 10−1 | 1 decilux | 2.5 decilux | Full Moon on a clear night[1][2][3] |
| 100 | 1 lux | < 1 lux | Extreme of darkest storm clouds, sunset or sunrise |
| 101 | 1 decalux | 40 lux | Fully overcast, sunset or sunrise |
| 102 | 1 hectolux | < 200 lux | Extreme of darkest storm clouds, midday |
| 400 lux | Sunrise or sunset on a clear day (ambient illumination) | ||
| 104 | 10 kilolux | 10–25 kilolux | Typical overcast day, midday |
| 20 kilolux | Shade illuminated by entire clear blue sky, midday | ||
| 105 | 100 kilolux | 110 kilolux | Bright sunlight |
| 120 kilolux | Brightest sunlight |
Luminance
editThis section lists examples of luminances, measured in candelas per square metre and grouped by order of magnitude.
| Factor (cd/m2) |
Multiple | Value | Item |
|---|---|---|---|
| 10−6 | μcd/m2 | 1 μcd/m2 | Absolute threshold of vision[4] |
| 10−5 | |||
| 10−4 | |||
| 10−3 | mcd/m2 | 400 μcd/m2 | Darkest sky[5] |
| 1 mcd/m2 | Night sky[6] | ||
| 1.4 mcd/m2 | Typical photographic scene lit by full moon[7] | ||
| 10−2 | 5 mcd/m2 | Approximate scotopic/mesopic threshold[8] | |
| 10−1 | |||
| 100 | cd/m2 | 2 cd/m2 | Floodlit buildings, monuments, and fountains[9] |
| 101 | 5 cd/m2 | Approximate mesopic/photopic threshold[8] | |
| 25 cd/m2 | Typical photographic scene at sunrise or sunset[7] | ||
| 30 cd/m2 | Green electroluminescent source[5] | ||
| 102 | 55 cd/m2 | Standard SMPTE cinema screen luminance[10] | |
| 80 cd/m2 | Monitor white in the sRGB reference viewing environment | ||
| 250 cd/m2 | Peak luminance of a typical LCD monitor[11][12] | ||
| 103 | kcd/m2 | 700 cd/m2 | Typical photographic scene on overcast day[7][9][12] |
| 2 kcd/m2 | Average cloudy sky[5] | ||
| 2.5 kcd/m2 | Moon surface[5][6] | ||
| 104 | 5 kcd/m2 | Typical photographic scene in full sunlight[7][9] | |
| 7 kcd/m2 | Average clear sky[4][5][6][12] | ||
| 10 kcd/m2 | White illuminated cloud[6] | ||
| 12 kcd/m2 | Fluorescent lamp[5][6] | ||
| 105 | 75 kcd/m2 | Low pressure sodium-vapor lamp[6] | |
| 130 kcd/m2 | Frosted incandescent light bulb[5][6][12] | ||
| 106 | Mcd/m2 | 600 kcd/m2 | Solar disk at horizon[5] |
| 107 | 7 Mcd/m2 | Filament of a clear incandescent lamp[13] | |
| 108 | 100 Mcd/m2 | Possible retinal damage[4] | |
| 109 | Gcd/m2 | 1.6 Gcd/m2 | Solar disk at noon[5][6] |
See also
editNotes and references
edit- ^ a b c d e Paul Schlyter, Radiometry and photometry in astronomy FAQ (2006)
- ^ "Petzl reference system for lighting performance". Archived from the original on 2008-06-20. Retrieved 2007-04-24.
- ^ Kyba, Christopher C M; Mohar, Andrej; Posch, Thomas (2017-02-01). "How bright is moonlight?". Astronomy & Geophysics. 58 (1): 1.31–1.32.
- ^ a b c Hahn, Lance (1996). "Photometric Units". University of Pennsylvania Medical Center, Department of Neuroscience. Retina Reference. Robert G. Smith. Retrieved 2013-10-10. (see http://retina.anatomy.upenn.edu/~rob/lance/articles.html for the references within)
- ^ a b c d e f g h i Mischler, Georg. "Lighting Design Glossary – Luminance". schorsch.com. Retrieved 2013-10-10.
- ^ a b c d e f g h "Lighting Application". NVC Lighting Technology Corporation. Archived from the original on 2012-05-19. Retrieved 2013-10-10.
- ^ a b c d based on Orders of magnitude (illuminance), assuming a typical photographic scene has the same reflectance as an 18% gray card
- ^ a b Halonen, Liisa; Bizjak, Grega. "CIE Mesopic photometry – implementation for outdoor lighting" (PDF). University of Ljubljana, Faculty of Electrical Engineering, laboratory of Lighting and Photometry. Retrieved 2013-10-10.
- ^ a b c based on this table of exposure values, assuming a reflected-light meter calibration constant of 12.5 cd·s/m2
- ^ "Screen Luminance Data Sheet" (PDF). Harkness Screens International. Archived from the original (PDF) on 2012-02-27. Retrieved 2013-10-10.
- ^ "Brightness and Contrast Ratio". Screen Tek. Archived from the original on 2013-08-26. Retrieved 2013-10-10.
- ^ a b c d When sources quote wide ranges of possible values, a (rounded) geometric mean of those values is reported here.[why?] The luminance of the sky in particular, varies by location, season, weather, time of day and part of the sky. The sky near the horizon is often about half as bright as at zenith, which in turn is often about half as bright as the sky near the Sun. Dr. Andrew J. Marsh has created an interactive web application that can be used to visualise different sky conditions.
- ^ "Basics of light and lighting" (PDF). Philips Lighting Academy. 2008. p. 29. Archived from the original (PDF) on 2013-10-19. Retrieved 2013-10-18.