4 REPORT OF THE INSTITUTE OF INDUSTRIAL SCIENCE, UNIVERSITY OF TOKYO 
considered just proper for panchromatic film. The comparison of 7 at that time calculated by 
Gevaert is as shown in Table 1. 
Thus, in interpreting aerial photos, it can be said that infrared photos are better suited 
to reproduce slight changes on the ground since the contrast of the image gained from infrared 
film is higher than that of panchromatic photos. 
3 PREREQUISITE TO THE TAKING OF 
| INFRARED AERIAL PHOTOS 
3.1 PROPERTY OF SENSITIVE EMULSION 
Fig 2 is a series of charts showing the comparison of color sensitivity inherent in the 
B representative sensitive emulsion now in use in aerial photos and that in the emulsion of in- 
l| frared films. 
Fig 2 indicates color 
Legent sensitivity inherent in silver 
halide, which is the material 
for sensitive emulsion. Fig 
2.2 shows color sensitivity 
of orthochromatic emulsion 
Part sengitive which has the property of 
so tno. film being sensitive to the colors 
up to blue. Fig 2-3 shows 
color sensitivity of panchro- 
  
  
     
    
|| 2. Orthochromatic 
matic emulsion which is now 
in universal use. It has the 
property of being sensitive 
to wave lengths from 450 
my to 670 my, but it is ob- 
served that color sensitivity 
  
  
  
  
to green somewhat deterio- 
rated. Fig 2-4 shows color 
sensitivity of emulsion used 
AU 
AA for infrared films. It has 
| 4. Infrared the property of being sen- 
  
| 1 } ; ] i l “a . 
p T tive to a part of purplish 
00 00 800 SI 
ioo Wave a ( s 00 7 blue, red color section above 
[| ny the wave length of 700 mu 
Fig. 2 Comparison of color sensitivity of films. and further to 860mg of 
infrared ray. 
A plane charged with a mission of taking aerial photos flies so fast that the low-speed 
shutter cannot be used. This makes it impossible to use emulsion which requires long exposure. 
The emulsion that now can be used for infrared aerial photos is restricted to one which has 
a wave length up to around 860 my. Since the sensitivity of this infrared films used in our 
studies is almost the same as that of panchromatic films, no inconvinience does come not at 
  
  
taking photos. 
Infrared film for the exclusive use of aerial photography has not yet been produced in