The Scheinergrade (Sch.) system was devised by the German astronomer Julius Scheiner (1858–1913) 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.
The Scheinergrade ( Sch . ) system was devised by the German astronomer Julius Scheiner ( 1858–1913 ) 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 do degrees Scheiner indicate?
What do degrees Scheiner indicate ?
the speed of a plate
the speed of a plate