Understanding Neutron Radiography Reading V-Kodak Part 2 of 3

4. A change in processing conditions causes a change in effective film speed.
If the processing of the radiographs differs from that used for the
exposures from which the chart was made, the correction factor must be
found by experiment.
5. The chart gives exposures to produce a certain density. If a different
density is required, the correction factor may be calculated from the film's
characteristic curve (See "The Characteristic Curve").
6. If the type of screens is changed, for example from lead foil to fluorescent,
it is easier and more accurate to make a new exposure chart than to
attempt to determine correction factors.
Charlie Chong/ Fion Zhang
Radiography in Modern Industry. Rochester, NY: Eastman Kodak Co. 1980