Understanding Neutron Radiography Reading V-Kodak Part 2 of 3

■ Example 2: Film X has a higher contrast than Film Z at D = 2.0 (See
Figure 47) and also lower graininess. Suppose that, for these reasons, it is
desired to make the aforementioned radiograph on Film X with a density of
2.0 in the same region of maximum interest. Place the straightedge on Figure
54 so that it cuts the scale for Film Z at 2.0. The reading on the outside scales
is then 41, as in Example 1. When the straightedge is placed across the Film
X scale at 2.0, the reading on the outside scale is 81. In the previous example,
the exposure for a density of 2.0 on Film Z was found to be 50 mA-min. In
order to give a density of 2.0 on Film X, this exposure must be multiplied by
the ratio of the two scale readings just found--81/41 = 1.97. The new
exposure is therefore 50 x 1.97 or 98 mA-min.
Charlie Chong/ Fion Zhang
Radiography in Modern Industry. Rochester, NY: Eastman Kodak Co. 1980