d. Class 4: These high-speed films, by comparison, are considered to have a low signal-to-noise ratio and
include Agfa D7, Kodak Type AA, and Fuji IX 100.
This classification differs from others because it is based upon the signal-to-noise ratio rather than speed. Figure 6-12
is a bar chart showing the relationships of signal-to-noise ratios, film speed, and detail resolution capabilities of the
different film classes. Table 6-3 and Table 6-4 are a more detailed guide to film classification. It is not inclusive of all
the film types or manufactures that may be authorized for use since manufacturers may introduce new films from time
to time. Specific inspection instructions may specify film other than what is listed. Each manufacturer has a particular
designation for films. Small variations may be noted in film speed and contrast of the films made by the different
manufacturers within a particular class.
Figure 6-12. Relationship between Signal-to-Noise Ratios and Speeds of Film.