Here is a question about this article: The Scheinergrade (Sch.) system was devised by the German astronomer Julius Scheiner (18581913) in 1894 originally as a method of comparing the speeds of plates used for astronomical photography. Scheiner's system rated the speed of a plate by the least exposure to produce a visible darkening upon development. Speed was expressed in degrees Scheiner, originally ranging from 1 Sch. to 20 Sch., where an increment of 19 Sch. corresponded to a hundredfold increase in sensitivity, which meant that an increment of 3 Sch. came close to a doubling of sensitivity.
What is the answer to this question: What is the Scheinergrade system used for?
comparing the speeds of plates used for astronomical photography