The unit of luminance, the brightness of a surface, in the centimeter-gram-second electromagnetic system of units = 1 candle per square centimeter. Adopted by the International Commission on Illumination (CIE) in 19xx. Symbol, sb. The stilb and its symbol were included in Resolution 7 of the 9th CGPM (1948).
One stilb corresponds to 1 candela per square centimeter in SI units. Although in common use in Europe,¹ in North America “the preferred practice is to use self-explanatory terms such as candle per square inch and candle per square meter.”² Currently, this quantity would be expressed in candela per square meter.
According to the current national standard in the United States³, the stilb is not to be used. In 1971, the European Economic Community directed that use of this unit cease by 31 December 1977.⁴
Google's N-gram viewer shows the declining usage of the term. Note however that the count includes the surname “Stilb”, and that it is of books in English. The result would be quite different for publications in German.
Some examples of magnitudes in stilb:⁵
|Surface||Luminance in stilbs|
|clear blue sky||0.2 – 0.6|
|overcast sky||0.3 – 0.7|
|filament of an incandescent
(tungsten) light bulb
|crater in a plain carbon arc lamp||16,000|
|sun at zenith||165,000|
1. Parry Moon.
System of photometer concepts.
Journal of the Optical Society of America, volume 32, number 6 (June 1942).
Page 355: “The lumen was proposed by Blondel in 1894 and is now universally accepted. The names, phot and stilb were likewise coined by Blondel (1921) and are in general use on the Continent.”
2. American Standard Definitions of Electrical Terms.
New York: American Institute of Electrical Engineers, 1941.
3. IEEE/ASTM SI 10™-2002.
American National Standard for Use of the International System of Units (SI): The Modern Metric System.
New York: IEEE, 30 December 2002.
See Section 3.3.3.
4. European Economic Community, Council Directive of 18 October 1971 on the approximation of the laws of the Member States relating to units of measurement (Directive 71/354/EEC), Annex, Chapter III.
5. John W[illiam] T[udor] Walsh.
Photometry. 3rd ed.
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Last revised: 11 September 2011.