These films represent many of 
the general purpose 
applications in aerial 
photography, infact, the 
Double-X film has had 
widespread use in most aerial 
survey work. The Kodak film's 
wide exposure latitude, 
relatively fine grain, average 
contrast, and fast emulsion 
speed has made it the standard 
survey emulsion. 
The Agfa 200 film may be viewed 
in the same context as the 
Double-X, however, due to its 
higher contrast (Table 3) it 
has been applied in conditions 
of low brightness ranges such 
as photography of uniform 
forest canopies, grassland 
zones, and arctic vegetation. 
Its spectral sensitivity, being 
about 7 60 nm. , has even lead to 
its use as an infrared film 
substitute, however, the Agfa 
200 suitability as an infrared 
substitute emulsion may be 
questionable (Figure 4). Much 
personal preference and opinion 
surround this issue and more 
objective research is required. 
For 70 mm. large scale 
photography it is noted that 
for forestry applications the 
interpreter preference 
decreases as emulsion spectral 
sensitivity increases [18]. The 
HP5 emulsion tends to be a 
lower contrast emulsion than 
both the Double-X film and the 
Agfa 200 film (Table 3) thus 
possibly suited to record high 
brightness range conditions 
such as found in mountainous 
regions. 
Very high speed emulsions. 
Only one film currently 
occupies this class: the Kodak 
Tri-X 2403 emulsion. It is 
characterized by relatively low 
contrast, fair resolution, and 
very wide exposure latitude. 
The film has had low use due to 
its graininess being relatively 
high, this attribute has 
discouraged the topographical 
service sector from using the 
film because of enlarging 
factors used in analytical 
plotters of between six and 
fourteen times. But in cases 
where only a 2 times 
magnification pocket 
stereoscope is used, and where 
shadow detail is critical to 
the application as often is in 
large scale applications 
(<1:5000), would the virtues of 
this emulsion not be an 
advantage? Unfortunately, not 
much work has been done in 
240mm. format aerial 
photography but the film is 
highly regarded in 70mm. 
applications [18]. 
Agfa has developed and tested a 
film in this class, presumably 
with characteristic extension 
of the spectral sensitivity 
into the infrared. This 
emulsion, however, has not been 
released to the commercial 
market except for special 
applications. 
COLOR FILMS 
Color films fall into two broad 
classes: 
negative 
type 
and 
positive 
reversal 
type. 
The 
positive 
reversal 
films 
are 
further 
subdivided 
into 
true 
color and false color infrared. 
Negative Type Emulsions 
Two films are currently grouped 
in this class, they are the 
Kodak Aerocolor 2445 and the 
Agfa Avicolor 200 emulsions. 
The Kodak 2445 film has, until 
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