164:
674:
297:
789:
684:
579:
900:
664:
156:
1138:
269:. "Brightness" should never be used for quantitative description, but only for nonquantitative references to physiological sensations and perceptions of light.
507:
272:
The human eye is capable of seeing somewhat more than a 2 trillion-fold range. The presence of white objects is somewhat discernible under starlight, at
849:
598:
1169:
784:{\displaystyle \int _{\Omega _{\Sigma }}L_{\mathrm {v} }\mathrm {d} \Omega _{\Sigma }\cos \theta _{\Sigma }=M_{\mathrm {v} }=E_{\mathrm {v} }R}
1043:
1080:
280:(50 μlx), while at the bright end, it is possible to read large text at 10 lux (100 Mlx), or about 1000 times that of direct
1118:
1128:
1728:
recommend that photometric quantities be denoted with a subscript "v" (for "visual") to avoid confusion with radiometric or
1134:
1782:
1162:
500:, the illuminance stars cast on the Earth's atmosphere is used as a measure of their brightness. The usual units are
120:
1004:
972:
1349:
1155:
843:
1725:
1697:
839:
113:
1787:
1713:
1672:
1638:
1264:
983:
192:
172:
1039:
1294:
1027:
501:
1087:
203:
is the luminous flux per unit area emitted from a surface. Luminous emittance is also known as
1593:
1543:
1466:
1426:
835:
809:
673:
211:
1211:
1122:
1115:
915:
1776:
1255:
180:
1712:" are for length, time and luminous intensity respectively, not the symbols for the
1586:
1271:
1231:
1226:
227:
223:
219:
163:
91:
17:
681:
The luminance of a reflecting surface is related to the illuminance it receives:
1327:
827:
314:
255:
251:
83:
1677:
1481:
1372:
910:
285:
262:
196:
1334:
1275:
1066:
920:
504:
in the visible band. V-magnitudes can be converted to lux using the formula
497:
301:
266:
102:
31:
265:, but this leads to confusion with other uses of the word, such as to mean
281:
1315:
1309:
940:
98:
62:
1746:
1744:
1742:
296:
1729:
574:{\displaystyle E_{\mathrm {v} }=10^{(-14.18-m_{\mathrm {v} })/2.5},}
1370:
source area. The candela per square metre is sometimes called the
945:
CIE S 017:2020 ILV: International
Lighting Vocabulary, 2nd edition
895:{\displaystyle L_{\mathrm {v} }={\frac {E_{\mathrm {v} }R}{\pi }}}
672:
659:{\displaystyle m_{\mathrm {v} }=-14.18-2.5\log(E_{\mathrm {v} }).}
295:
231:
188:
106:
284:, although this can be very uncomfortable and cause long-lasting
1611:
1605:
1563:
1557:
239:
184:
79:
234:). Luminous exitance is measured in lm·m only, not lux. In the
1658:
Luminous efficacy normalized by the maximum possible efficacy
1402:
1396:
1081:"Formulae for converting to and from astronomy-relevant units"
1028:
http://www.unitconversion.org/unit_converter/illumination.html
319:
235:
215:
67:
1667:
791:
where the integral covers all the directions of emission
1734:
USA Standard Letter
Symbols for Illuminating Engineering
1067:"Radiometry and photometry in astronomy FAQ, section 7"
947:. CIE - International Commission on Illumination. 2020
852:
687:
601:
595:
is the apparent magnitude. The reverse conversion is
510:
123:
1129:
Library of Units and
Constants: Illuminance Quantity
677:
Comparison of photometric and radiometric quantities
254:
is a non-metric unit of illuminance that is used in
191:
illuminates the surface, wavelength-weighted by the
1137:using a camera's exposure meter. Also available in
112:
89:
73:
61:
44:
39:
894:
783:
658:
573:
150:
1000:International Electrotechnical Commission (IEC):
968:International Electrotechnical Commission (IEC):
996:
994:
964:
962:
304:for measuring illuminances in work environments
151:{\displaystyle {\mathsf {L}}^{-2}{\mathsf {J}}}
167:Illuminance diagram with units and terminology
1163:
8:
1633:Ratio of luminous flux to power consumption
1366:Luminous flux per unit solid angle per unit
27:Luminous flux incident on a surface per area
187:. It is a measure of how much the incident
1170:
1156:
1146:
1002:International Electrotechnical Vocabulary.
970:International Electrotechnical Vocabulary.
307:
1246:The lumen second is sometimes called the
876:
875:
868:
858:
857:
851:
771:
770:
756:
755:
742:
726:
717:
710:
709:
697:
692:
686:
643:
642:
607:
606:
600:
558:
548:
547:
530:
516:
515:
509:
142:
141:
132:
126:
125:
122:
162:
1689:
1040:"Illuminance - Recommended Light Level"
932:
238:system, the unit of illuminance is the
261:Illuminance was formerly often called
143:
127:
36:
1191:
1187:
1184:
1181:
7:
1750:Alternative symbols sometimes seen:
1135:Estimating Luminance and Illuminance
842:), the luminance is isotropic, per
1766:for luminous efficacy of a source.
1696:The symbols in this column denote
1046:from the original on April 3, 2022
1005:ref. 845-21-081, luminous exitance
877:
859:
846:. Then the relationship is simply
772:
757:
743:
727:
723:
718:
711:
698:
694:
644:
608:
549:
517:
25:
1399:(= lumen per square metre)
820:is the received illuminance, and
183:incident on a surface, per unit
588:is the illuminance in lux, and
1289:Luminous energy per unit time
650:
635:
555:
531:
1:
1520:lumen second per cubic metre
1312:(= lumen per steradian)
1502:Time-integrated illuminance
973:ref. 845-21-060, illuminance
1736:USAS Z7.1-1967, Y10.18-1967
1042:. The Engineering ToolBox.
834:In the case of a perfectly
214:illuminance is measured in
1804:
1585:Ratio of luminous flux to
1127:Knowledgedoor, LLC (2005)
29:
1732:quantities. For example:
1662:
1637:
1592:
1542:
1506:
1465:
1425:
1380:
1333:
1293:
1254:
1210:
1205:
1202:
1199:
1196:
292:Common illuminance levels
218:(lx), or equivalently in
1507:Luminous energy density
1354:cd/m (= lm/(sr⋅m))
1350:candela per square metre
1150:SI photometry quantities
941:"Illuminance, 17-21-060"
195:to correlate with human
30:Not to be confused with
1762:for luminous flux, and
1726:Standards organizations
1716:litre, tesla and joule.
1641:, luminous coefficient
1442:lumen per square metre
1326:Luminous flux per unit
199:perception. Similarly,
896:
785:
678:
660:
575:
305:
168:
152:
1754:for luminous energy,
1429:, luminous emittance
1116:Illuminance Converter
897:
786:
676:
669:Relation to luminance
661:
576:
299:
166:
153:
850:
844:Lambert's cosine law
840:Lambertian reflector
685:
599:
508:
337:Shade on a sunny day
242:, which is equal to
121:
1783:Physical quantities
1639:Luminous efficiency
1178:
1093:on December 2, 2013
502:apparent magnitudes
193:luminosity function
1295:Luminous intensity
1281:lm (= cd⋅sr)
1147:
1121:2010-02-10 at the
1024: foot-candles
892:
781:
679:
656:
571:
311:Lighting condition
306:
201:luminous emittance
169:
148:
93:SI base units
18:Luminous emittance
1686:
1685:
1594:Luminous efficacy
1544:Luminous efficacy
1467:Luminous exposure
1427:Luminous exitance
1258:, luminous power
1133:Kodak's guide to
984:Luminous exitance
890:
836:diffuse reflector
810:luminous exitance
808:is the surface's
489:
488:
205:luminous exitance
161:
160:
16:(Redirected from
1795:
1767:
1765:
1761:
1757:
1753:
1748:
1737:
1723:
1717:
1694:
1646:
1601:
1553:
1517:
1478:
1439:
1393:
1346:
1306:
1274:(= candela
1268:
1223:
1179:
1172:
1165:
1158:
1151:
1103:
1102:
1100:
1098:
1092:
1086:. Archived from
1085:
1077:
1071:
1070:
1065:Schlyter, Paul.
1062:
1056:
1055:
1053:
1051:
1036:
1030:
1025:
1023:
1020:
1013:
1007:
998:
989:
981:
975:
966:
957:
956:
954:
952:
937:
901:
899:
898:
893:
891:
886:
882:
881:
880:
869:
864:
863:
862:
797:
790:
788:
787:
782:
777:
776:
775:
762:
761:
760:
747:
746:
731:
730:
721:
716:
715:
714:
704:
703:
702:
701:
665:
663:
662:
657:
649:
648:
647:
613:
612:
611:
580:
578:
577:
572:
567:
566:
562:
554:
553:
552:
522:
521:
520:
484:
478:
467:
461:
450:
444:
433:
427:
416:
410:
399:
393:
382:
376:
365:
359:
348:
342:
308:
279:
277:
249:
247:
157:
155:
154:
149:
147:
146:
140:
139:
131:
130:
94:
57:
37:
21:
1803:
1802:
1798:
1797:
1796:
1794:
1793:
1792:
1773:
1772:
1771:
1770:
1763:
1759:
1755:
1751:
1749:
1740:
1724:
1720:
1695:
1691:
1682:
1644:
1599:
1549:
1546:(of radiation)
1516:
1510:
1477:
1471:
1461:from a surface
1438:
1432:
1392:
1386:
1345:
1339:
1318:(= lm/sr)
1305:
1299:
1267:
1261:
1222:
1216:
1212:Luminous energy
1189:
1177:
1176:
1149:
1123:Wayback Machine
1112:
1107:
1106:
1096:
1094:
1090:
1083:
1079:
1078:
1074:
1064:
1063:
1059:
1049:
1047:
1038:
1037:
1033:
1026:, according to
1021:
1018:
1016:
1014:
1010:
999:
992:
982:
978:
967:
960:
950:
948:
939:
938:
934:
929:
907:
871:
870:
853:
848:
847:
838:(also called a
825:
819:
816:
807:
804:
796:
792:
766:
751:
738:
722:
705:
693:
688:
683:
682:
671:
638:
602:
597:
596:
594:
587:
543:
526:
511:
506:
505:
494:
482:
476:
465:
459:
448:
442:
431:
425:
414:
408:
397:
391:
380:
374:
363:
357:
346:
340:
294:
275:
273:
245:
243:
124:
119:
118:
92:
76:
56:
50:
47:
35:
28:
23:
22:
15:
12:
11:
5:
1801:
1799:
1791:
1790:
1785:
1775:
1774:
1769:
1768:
1738:
1718:
1688:
1687:
1684:
1683:
1681:
1680:
1675:
1670:
1664:
1660:
1659:
1656:
1651:
1649:
1647:
1642:
1635:
1634:
1631:
1614:
1608:
1602:
1597:
1596:(of a source)
1590:
1589:
1583:
1566:
1560:
1554:
1547:
1540:
1539:
1537:
1524:
1521:
1518:
1514:
1508:
1504:
1503:
1500:
1487:
1484:
1479:
1475:
1469:
1463:
1462:
1457:Luminous flux
1455:
1446:
1443:
1440:
1436:
1430:
1423:
1422:
1417:Luminous flux
1415:
1406:
1405:(= lm/m)
1400:
1394:
1390:
1384:
1378:
1377:
1364:
1355:
1352:
1347:
1343:
1337:
1331:
1330:
1324:
1319:
1313:
1307:
1303:
1297:
1291:
1290:
1287:
1282:
1279:
1269:
1263:
1259:
1252:
1251:
1244:
1235:
1229:
1224:
1220:
1214:
1208:
1207:
1204:
1201:
1198:
1194:
1193:
1190:
1186:
1183:
1175:
1174:
1167:
1160:
1152:
1148:
1143:
1142:
1131:
1125:
1111:
1110:External links
1108:
1105:
1104:
1072:
1057:
1031:
1008:
990:
976:
958:
931:
930:
928:
925:
924:
923:
918:
916:Exposure value
913:
906:
903:
889:
885:
879:
874:
867:
861:
856:
832:
831:
823:
821:
817:
814:
812:
805:
802:
794:
780:
774:
769:
765:
759:
754:
750:
745:
741:
737:
734:
729:
725:
720:
713:
708:
700:
696:
691:
670:
667:
655:
652:
646:
641:
637:
634:
631:
628:
625:
622:
619:
616:
610:
605:
592:
585:
570:
565:
561:
557:
551:
546:
542:
539:
536:
533:
529:
525:
519:
514:
493:
490:
487:
486:
480:
474:
473:Overcast night
470:
469:
463:
457:
453:
452:
446:
440:
436:
435:
429:
423:
419:
418:
412:
406:
402:
401:
395:
389:
385:
384:
378:
372:
368:
367:
361:
355:
351:
350:
344:
338:
334:
333:
330:
327:
323:
322:
317:
312:
293:
290:
159:
158:
145:
138:
135:
129:
116:
110:
109:
96:
87:
86:
77:
74:
71:
70:
65:
59:
58:
54:
48:
46:Common symbols
45:
42:
41:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
1800:
1789:
1786:
1784:
1781:
1780:
1778:
1747:
1745:
1743:
1739:
1735:
1731:
1727:
1722:
1719:
1715:
1711:
1707:
1703:
1699:
1693:
1690:
1679:
1676:
1674:
1671:
1669:
1666:
1665:
1661:
1657:
1655:
1652:
1650:
1648:
1643:
1640:
1636:
1632:
1630:
1626:
1622:
1618:
1615:
1613:
1609:
1607:
1603:
1598:
1595:
1591:
1588:
1584:
1582:
1578:
1574:
1570:
1567:
1565:
1561:
1559:
1555:
1552:
1548:
1545:
1541:
1538:
1536:
1532:
1528:
1525:
1522:
1519:
1513:
1509:
1505:
1501:
1499:
1495:
1491:
1488:
1485:
1483:
1480:
1474:
1470:
1468:
1464:
1460:
1456:
1454:
1450:
1447:
1444:
1441:
1435:
1431:
1428:
1424:
1421:on a surface
1420:
1416:
1414:
1410:
1407:
1404:
1401:
1398:
1395:
1389:
1385:
1383:
1379:
1375:
1374:
1369:
1365:
1363:
1359:
1356:
1353:
1351:
1348:
1342:
1338:
1336:
1332:
1329:
1325:
1323:
1320:
1317:
1314:
1311:
1308:
1302:
1298:
1296:
1292:
1288:
1286:
1283:
1280:
1277:
1273:
1270:
1266:
1260:
1257:
1256:Luminous flux
1253:
1249:
1245:
1243:
1239:
1236:
1233:
1230:
1228:
1225:
1219:
1215:
1213:
1209:
1195:
1180:
1173:
1168:
1166:
1161:
1159:
1154:
1153:
1145:
1140:
1136:
1132:
1130:
1126:
1124:
1120:
1117:
1114:
1113:
1109:
1089:
1082:
1076:
1073:
1068:
1061:
1058:
1045:
1041:
1035:
1032:
1029:
1012:
1009:
1006:
1003:
997:
995:
991:
988:
985:
980:
977:
974:
971:
965:
963:
959:
946:
942:
936:
933:
926:
922:
919:
917:
914:
912:
909:
908:
904:
902:
887:
883:
872:
865:
854:
845:
841:
837:
829:
822:
813:
811:
801:
800:
799:
778:
767:
763:
752:
748:
739:
735:
732:
706:
689:
675:
668:
666:
653:
639:
632:
629:
626:
623:
620:
617:
614:
603:
591:
584:
568:
563:
559:
544:
540:
537:
534:
527:
523:
512:
503:
499:
491:
481:
475:
472:
471:
464:
458:
455:
454:
447:
441:
438:
437:
430:
424:
421:
420:
413:
407:
405:Deep twilight
404:
403:
396:
390:
387:
386:
379:
373:
371:Very dark day
370:
369:
362:
356:
353:
352:
345:
339:
336:
335:
331:
328:
325:
324:
321:
318:
316:
313:
310:
309:
303:
298:
291:
289:
287:
283:
270:
268:
264:
259:
257:
253:
241:
237:
233:
229:
225:
221:
217:
213:
208:
206:
202:
198:
194:
190:
186:
182:
181:luminous flux
179:is the total
178:
174:
165:
136:
133:
117:
115:
111:
108:
104:
100:
97:
95:
88:
85:
81:
78:
72:
69:
66:
64:
60:
53:
49:
43:
38:
33:
19:
1733:
1721:
1709:
1705:
1701:
1692:
1653:
1628:
1624:
1620:
1616:
1587:radiant flux
1580:
1576:
1572:
1568:
1550:
1534:
1530:
1526:
1511:
1497:
1493:
1489:
1472:
1458:
1452:
1448:
1433:
1418:
1412:
1408:
1387:
1381:
1371:
1367:
1361:
1357:
1340:
1321:
1300:
1284:
1247:
1241:
1237:
1227:lumen second
1217:
1144:
1095:. Retrieved
1088:the original
1075:
1060:
1048:. Retrieved
1034:
1011:
1001:
987:Drdrbill.com
986:
979:
969:
949:. Retrieved
944:
935:
833:
680:
589:
582:
495:
439:Quarter moon
354:Overcast day
315:Foot-candles
271:
260:
224:square metre
209:
204:
200:
176:
170:
63:SI unit
51:
1382:Illuminance
1328:solid angle
1015:One phot =
828:reflectance
286:afterimages
278:10 lux
256:photography
252:foot-candle
177:illuminance
84:foot-candle
75:Other units
40:Illuminance
1788:Photometry
1777:Categories
1698:dimensions
1678:Radiometry
1673:Photometry
1663:See also:
1604:lumen per
1556:lumen per
1482:lux second
927:References
911:Irradiance
263:brightness
197:brightness
173:photometry
1368:projected
1335:Luminance
1276:steradian
1188:Dimension
1182:Quantity
921:Luminance
888:π
744:Σ
740:θ
736:
728:Σ
724:Ω
699:Σ
695:Ω
690:∫
633:
624:−
618:−
541:−
535:−
498:astronomy
492:Astronomy
456:Starlight
422:Full moon
302:lux meter
267:luminance
248: lux
134:−
114:Dimension
32:Luminance
1419:incident
1139:PDF form
1119:Archived
1044:Archived
951:20 April
905:See also
388:Twilight
332:100,000
326:Sunlight
282:sunlight
212:SI units
1708:" and "
1523:lm⋅s/m
1459:emitted
1310:candela
1206:Symbol
1200:Symbol
1097:Nov 23,
1050:July 7,
1017:929.030
826:is the
485:0.0001
479:0.00001
349:10,000
329:10,000
1730:photon
1248:talbot
1192:Notes
798:, and
581:where
468:0.001
462:0.0001
366:1,000
250:. The
220:lumens
1714:units
1486:lx⋅s
1445:lm/m
1272:lumen
1203:Name
1197:Name
1185:Unit
1091:(PDF)
1084:(PDF)
621:14.18
538:14.18
483:00000
466:00000
451:0.01
449:00000
445:0.001
432:00000
415:00000
343:1,000
189:light
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1606:watt
1558:watt
1099:2013
1052:2022
953:2023
477:0000
460:0000
443:0000
434:0.1
428:0.01
426:0000
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398:0000
392:0000
383:100
240:phot
222:per
185:area
80:phot
1758:or
1700:; "
1610:lm/
1562:lm/
1397:lux
1373:nit
1234:⋅s
1022:001
1019:400
733:cos
630:log
627:2.5
564:2.5
496:In
411:0.1
400:10
381:000
375:000
360:100
320:Lux
246:000
236:CGS
216:lux
210:In
171:In
90:In
68:lux
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1668:SI
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105:·
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