On the Test of a Polyester Aerial Photographic Film T-008 
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6) Solubility of the emulsion 
The emulsion melts at 77°C in 0.7% solution of sodium carbonate, and the 
fixing speed is 3 minutes 40 seconds with F-5 fixing solution (20°C). 
IV. Film shrinkage 
1. General 
The shrinkage of a photographic film is classified as follows. 
a) Uniform shrinkage; b) Affinity; c) Irregular shrinkage. 
The effect of the uniform shrinkage of a film is compensated by the minor 
adjustment of camera constant C of plotting instruments and the effect of 
affinity (the difference of lateral and longitudinal shrinkage) is disregarded 
in most cases at present. Under these circumstances we tried to clarify the 
irregular shrinkage of the new film by the following two investigations. 
a) Investigation on the closing error of relative orientation. 
b) Laboratory test. 
Though we expected very small irregular shrinkage of the new film, the 
following results of the investigations betrayed our expectation to some extent. 
1) The uniform shrinkage of T-008 photographic film is about 1/5 of TAC 
film. 
2) The laboratory test proves that the irregular shrinkage of polyester 
base is about 1/3 of TAC base. 
3) In spite of this, the results deduced from the investigation on the 
closing errors of relative orientations and the distribution of residual 
vertical parallaxes prove nearly equal irregular shrinkage of the new 
film to that of TAC film. 
The contradiction between 2) and 3) is supposed due to the uneven flatten- 
ning of film at the exposure and at the printing. In this respect further investi 
gation on the sucking and the pressing mechanisms by the exposure and the 
printing is thought to be necessary. 
2. Investigation on the irregular shrinkage by the residual parallax of relative orientation 
1) Test materials 
No local unsharpness was detected by the inspection of 324 negatives with 
bare eyes and a magnifier. Among these negatives 36 stereoscopic pairs of 
photographs were selected as test materials for the relative orientation and the 
investigation of residual vertical parallaxes. The stereoscopic pairs consist of 
3 consecutive negatives which are located at the top, middle and end of each 
film roll photographed by 4 aerial surveying companies. 
2) Observation 
The observation of stereomodels executed with two Autograph A-7, one 
Stereoplanigraph C/8 and one Precise Comparator. The relative orientation 
was performed by Prof. Hallert’s method and the residual vertical parallaxes 
at relative orientation points 1-6 and 3'-6' (located inner side of 3-6) were 
measured.