354 
Fishery Bulletin 108(3) 
Figure 1 
Drop stereo-video camera system showing (A) the quick-responding winch, and (B) the locations of 
cameras and lights in the aluminum frame. (C) The still-frame camera system, which is deployed 
in a midwater trawl. (D) The camera housings (shown) were constructed from deep-water trawl 
floats which provided buoyancy and reduced the weight of the cameras. 
power Leeson wet-duty motor powered by 100 V AC. 
The winch speed ranged from 43 m/min (with a bare 
drum) to approximately 58 m/min (with a full drum). 
The approximate square-in area of the winch was 48 
in 2 (0.031 m 2 ) and its weight was 155 lb (70.3 kg). 
The drum was 16 in (40.6 cm) in circumference and 
was filled with 1312 ft (400 m) of 3/16-in (4.72-mm) 
conducting wire. The wire had a breaking strength of 
3300 lb (1497 kg) and was connected to the camera sled 
with a cable-grip. The video feed from the cameras was 
passed up a cable and through a four-conductor slip 
ring mounted on the winch and routed into a junction 
box where it was connected to a monitor for real-time 
viewing. 
The protective cage around the camera and lights was 
constructed of 1.5-in (3.81-cm) aluminum tubing, and 
the interior members of the frame were composed of 6- 
in (15.24-cm) aluminum channel (Fig. IB). A tail chain 
was attached to the rear of the ventral surface of the 
cage to drag along the seafloor to help keep the camera 
unit in contact with the seafloor and oriented forward 
during deployment. The tail chain was connected to the 
cage by a short piece of twine to act as a “weak link” in 
case the tail chain snagged on the seafloor. 
The underwater video was recorded by two identical 
Sony TR-900 camcorders (Sony Electronics Inc., San 
Diego, CA) located inside the camera housings. The 
cameras were capable of collecting 720 p progressive 
scan video images at a resolution of 720x480 pixels. 
The video was recorded to digital video tapes for a 
maximum of one hour per tape. Because the cable was 
too long (400 m) to transmit a standard video signal, it 
was transformed by using a video balun (in the camera 
housing) and a receiver (at the winch) to reconvert the 
video signal back to a viewable picture of the seafloor 
to use for real-time navigation. Cameras were placed 
in separate housings constructed of titanium tubing 
and that had a glass dome port (pressure-rated to 
3000 m depth) covering the lens. The lens of each 
camera was keyed to its port to prevent the camera 
from being inserted into the housing in a position 
other than the exact keyed position and stabilized the 
relative position of the cameras from deployment to 
deployment — an important consideration for accurate 
