WORKING GROUP 1 
WELANDER 
33 
Fig. 5. Transfer mountain for the lens Ag 38 Focus for max transfer at 25 1/mm 
In the horizontal direction the figures on the axes denote the distance from image centre in 
centimeters. In the vertical direction the figures denote focus shifts in tenths of a millimeter. 
for the whole image field is being made. Fig. 5 shows such a contrast mountain 
containing the field about 20° around the image centre for a 6" Aviogon 
lens. 
The emulsion-function was received from Eastman Kodak. The film is a weak 
point in the system, dependent among other son the granularity and the optical 
system of the micro-photometer. Plus X film was used (fig. 6) developed to 
gamma 1.0. 
The shutter-function was determined for the setting 1/250 sec, 1,500 m altitude 
and the velocity 249 km/h. Laboratory measurements, however, furnished a 
curve which gave the efficiency of 67% and the effective exposure time 1/280 
sec for the Aviogon lens. 
The vibration-function was at first obtained with the aid of aerial photography 
of a light source at night with open shutter. The amplitude was 0.03 mm and 
the frequency 15 cps. For calculation of the T-function for the maximum effect 
the shutter speed 1/280 sec was used (fig. 6). 
The image motion function was calculated for the same conditions as the above 
shutter function (fig. 6) The mathematical expression is the ratio (sin x) : x, 
where x is the linear motion as measured in radians during the exposure time. 
The haze-function is important for higher altitudes, for example 3,000 m 
and above. The contrast reduction is dependent on the luminance values of the 
ground as shown by, among others, the author [5], but likely to be independent