THE CAMERAS AND TECHNIQUES USED 



The type of form used for recording the results of 

 the examination of each photograph is shown in figure 3A. 

 Figure 3B shows the back of this form on which was listed 

 the properties of any water, sediment, or animal sample 

 taken in the area. 



Three types of deep-sea camera systems were 

 employed for the collection of the bottom photographs. Type 

 I (fig. 4) has a tilted semiwide- angle lens of 30 mm focal 

 length, and uses 35 mm film and a repeating electronic 

 flash light mounted in an upright frame. A bottom contact 

 switch activates the light and causes the film to advance 

 each time a lowered weight touches the sea floor. All 

 photos taken with this apparatus were low obliques (30° 

 from the vertical) at a preset target distance of 6 feet 

 underwater. Figure 4 also shows the grid scale used for 

 making measurements on the photos taken with this camera 

 system. 



Type II camera (fig. 5) has a sled-type frame sup- 

 porting a 35 mm camera and a flash unit which can rotate 

 about a common axis to give vertical or oblique photos. 

 Normally the camera angle was set close to the horizontal 

 (15° from the horizontal) to permit greater bottom coverage 

 even though the photo scale was more distorted. This 

 camera was usually lowered to a preselected target distance 

 and then allowed to drift over the sea floor using sonar to 

 control the height above the bottom. Photographs were 

 taken automatically at preset time intervals. Excessive 

 heave and roll of the lowering vessel caused unwanted 

 deviations from acceptable depths of focus. Figure 5 

 shows the optics and grid overlay for photo measurements. 



The Type III camera is a 35 mm Edgerton, 

 Germeshausen, and Grier stereo underwater system. 

 Photo pairs were taken with the camera axes oriented 

 vertically and set at a prefixed separation. Figure 6 shows 

 the optics and field coverage for this system. 



The grids for the three camera systems are con- 

 structed of clear plastic. They were applied as overlays 

 in examining the bottom photos, and established scale for 



20 



