F. E. Ross.
The Physics of the Developed Image.
New York: D. Van Nostrand, 1924.
See the discussion of the Greenwich, Ross, and Scheiner formulas.
log (d + a) = e log (b + k log E)
where
d = diameter of disc in image
E = exposure of plate
a, b, k, e = constants
| Equation | a | e | b | k |
|---|---|---|---|---|
| Greenwich | 0 | 2 | * | * |
| Ross | * | 2 | * | * |
| Scheiner | 0 | 1 | * | * |
* determined empirically