Difference between revisions of "Threshold of Illuminance"

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[[Category:Alphabetical Index]]
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[[Category:IALA Dictionary 1970-89 Edition]]
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[[Category:IALA Dictionary 2023 Revision]]

Latest revision as of 11:58, 4 February 2024

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Alternative term: Visual Threshold

The weakest illuminance produced at the eye which makes it possible to see a given source against a given background luminance.


Note: The internationally accepted value of the threshold of illuminance for observation of a light at night under typical maritime conditions is 2.10-7 lux (0.686 sea-mile candela, 2-1-060). This figure was agreed at the International Technical Conference of Lighthouse Authorities, Paris 1933. In Britain and U.S.A. this value is sometimes approximated by 0.67 sea-mile candela.




Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)