Commission VII 
    
  
Presented paper 1 
The Use of Colour Sensitive Films in Aerial 
Photography in U.S.S.R. 
by V. Y. MIKHAILOV 
I. Aerial photography. 
U.S.S.R. 
1. Colour pictures have come to be widely used in the U.S.S.R. 
In aerial surveying two types of negative film are employed at present: the three-layer 
film enabling the image to be obtained in colours closely resembling those of the objects 
recorded, and the two-layer, or spectrozonal, film producing an image in arbitrary, 
500 
300 400 500 
   
700 M4 
Fig. 1. Spectral sensitivity of 
the CN-film. 
speed of this film exceeds 
contrasting colours which greatly facilitates the 
interpretation of a variety of detail. The former 
(designated as CN) has the usual structure of its 
kind; its spectral characteristic curve is shown in 
Fig. 1. The sensitivity of the CN-1 film formerly used 
was the same as that of black-and-white film of 15 
DIN; it is being superseded by the CN-3 film whose 
speed is 20 DIN (70 unit of GOST as a minimum !)) 
and Gamma (y) approximating 1.0. 
The spectrozonal film (SN-2) is made of two lay- 
ers only, the sensitation maximum of the lower one, 
which is panchromatic, being reached at 4 — 650 mu, 
while that of the upper, which is infrachromatic, is 
attained at à = 735 mu. (Fig. 2.) There is no yellow 
layer between them, so the use of a yellow or orange- 
coloured filter becomes a must when taking photo- 
graphs. Upon development the upper layer shows 
light-blue and the lower is rendered magenta. The 
that of the CN-3 about 50-100 per cent, and its Gamma (y) is 2.0. 
Owing to vast territories of wooded land being surveyed in the U.S.S.R. the SN-2 film is 
more widely used as com- 
pared with the CN film. 
Experience has shown that 
pictures taken on the SN 
film, ie. those obtained in 
arbitrary colours, make the 
identification of a variety of 
detail much easier; more- 
over, since light filters may 
be employed, it is possible to 
take photographs from con- 
siderably higher altitudes. In 
this connection research is 
being made on the feasibili- 
ty of using other spectro- 
zonal films with different 
spectral characteristics and with a different distrib 
& Ia 
  
+2,0 
—— — RA MÀ 
T7 
——— M—— o o— 
  
LL —— —d4-——-—4 
  
  
  
  
  
  
ÉL—-—- 
— —— — — o Ro 7 —— ——4 
  
  
  
  
  
  
  
  
  
  
1) GOST — National Standards of U.S.S.R. 
500 500 700 
Fig. 2. Spectral sensitivity of the SN-film. 
ution of colour-forming components [1].