The approximate equation to determine the change in sea water 
depth owing to a change in the refractiye index of sea water 
at approximately 0 C temperature and 35 /00 salinity is pre- 
sented as follows: 
OF = 6.7#x10Dn Eq. 22 
where 
AZ change in sea water depth in meters. 
When 
An 0.004, then 
DZ 2,700m. 
In summary, a change of *5,700 meters in the depth of sea 
water at approximately 0°C temperature and 35 /oo salinity 
causes a change of -0.004 in the refractive index of the sea 
water which, in turn, causes a change of -0.05mm in the back 
focal distance that limits the resolution of the C201 lens 
working at f/4 to approximately 50 cycles per millimeter for 
a low contrast target (1.611). Film resolution in addition 
to water, lighting, shutter, and vibration conditions further 
reduce the system resolution of the operational camera appre- 
ciably. 
Grateful appreciation is extended to Roy M. Waxler, National 
Bureau of Standards, and to engineering consultant, CAPT 
Harry A. Jackson, P.E., for the cooperative assistance that 
was extended by acknowledged performers in their respective 
fields of science and engineering. 
Respectfully, 
Gaz m 7 ERE. 
G 
(/Gomer T. McNeil, P.E. 
GTMc /mmm 
ces A, Jones 
LT J. Coombs 
LCDR R. Lewis