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FILM TRANSPORT 
  
The film has to be advanced between the exposure of 
successive frames. With cycle times as short as 2 seconds, 
the fiim transport must take place in a very short time 
interval, i.e. force has to be applied which may well lead 
to elastic extension of the film prior to the exposure, and 
to a contraction later. 
PROCESSING OF THE NEGATIVE 
  
Processing of the negative film will here be understood 
as incorporating all steps necessary to obtain the processed 
negative from the exposed film. Since the aerial film is an 
elastic material coated with a gelatin layer and since the 
film has to undergo wetting and drying, many sources for 
dimensional changes are present. They wlll here be reviewed 
shortly. A more comprehensive review is given in [2]. 
Overall size changes can be caused by changes in 
temperature and relative humidity and by other factors. 
Nonuniform dimensional changes can be caused by the film 
structure and by unequal treatment over the area of a frame. 
Thermal and Relative Humidity Expansion 
At a constant relative humidity, film dimensions increase 
with an inerease in temperature and deerease with a drop in 
temperature. However, temperature and relative humidity are 
strongly correlated. An increase in temperature often results 
in a decrease of the relative humidity. Frequently, the