On the Test of a Polyester Aerial Photographic Film T-008 
105 
Characteristic curves are shown on Fig. 1, and the sensitivity deduced from 
them are given on a small table just above it. 
The following characteristics of the film is concluded from these values. 
1) The exposure index corresponds to 100-125 
The sensitivity seems to be somewhat slower than Super XX of EK, and 
a little faster than Aviphoto Pan 33 of Gevaert Co., Ltd. . 
2) Gamma 
As well known the contrast of a photographic film has very important in 
fluence on its practical applicability of the aerial photography. The labora 
tory test of the film proves that it has nearly equal or a little harder contrast 
than Super XX. But a surveying company reported the contrast was some 
what softer than Super XX. 
It seems that the discrepancy derives from using no filter by the laboratory 
test, although further investigation is not yet completed. 
3) Color sensitivity 
The spectral photograph Fig. 2 shows that the film is of super panchromatic 
type sensitive up to 670 mThis is similar to Super XX and Aviphoto 
Pan 33. 
Fig. 2. Spectral photograph of PET film. 
4) Resolving power and image sharpness 
The resolving power and the image sharpness were investigated by the 
ordinary method based on the reduction of a test target and the calculation 
Fig. 3. Resolving power tester 
(Koana type).