reseau plate which is positioned in the focal plane and holds the film 
flat, between the plate and the magazine pressure pad, at the moment of 
exposure. The UMEL cameras used in this work have been modified in this 
fashion. Other advantages of the UMEL camera include the larger format, 
the wider angular field of view, the between lens shutter, variable 
exposure timing and electronic stereo synchronisation, which is needed 
when the cameras are operated from a moving platform. 
Available underwater cameras are all basically non-metric. There is no 
underwater camera currently available approaching a terrestrial survey 
(metric) camera. Whether a metric camera in an underwater housing will 
ever be produced remains to be seen. It is, however, very doubtful 
whether the use of such a camera would be worthwhile in the underwater 
environment owing to seawater variations in temperature, density and 
salinity, which will influence camera behaviour and vary the distortion 
pattern of the photography. 
  
Benthos model 370-2 
UMEL DHC 70 (modified) 
  
  
Format 
Format size 
lens system 
Front Port 
Implications 
Field of view 
Focal length 
in water 
Shutter 
Magazine size 
  
35mm 
24 x 30mm 
28mm water 
corrected Nikkor 
Plane 
magnified image and 
reduced angular 
coverage 
559 
37mm approximately 
focal plane, 
electronic 
2000 exposures 
  
70mm 
52 x 52mm 
38mm Zeiss Biogon 
Domed (corrective) 
angular coverage 
preserved 
75° 
49mm approximately 
between lens,electronic 
70 exposures 
  
Special LED data chamber No 
features No film flattening 
and reseau 
No electronic stereo 
synchronisation 
Table I Basic characteristics of the Benthos model 370-2 
  
43 
and the modified UMEL DHC 70 cameras.