411 REFERENCE · Wiktionary
Scheiner speed
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
Etymology
The system was devised by the German astronomer Julius Scheiner in 1894.
Noun
The speed (expressed in degrees) of a plate used for astronomical photography, rated by the least exposure required to produce a visible darkening upon development.
en eponyms