altitude of 2000 feet for all parameters examined, except altitude 

 variations. The aircraft, a PSA, was equipped with a 6-inch focal-length 

 RC-8 camera, four 3-inch focal-length KA62 cameras, and four 80-millimeter 

 focal-length electric Hasselbad cameras. The RC-8 camera used a clear 

 antivignetting filter and a specially manufactured Ansco D500 color film 

 that did not have the blue sensitive layer. One of the KA62 cameras used 

 Kodak SO-397 color Ektachrome film, the other three KA62 cameras used 

 Kodak 2405 high-speed Panchromatic film with Wratten 57, 47, and 25A 

 filters. The camera equipped with the Wratten 47 filter malfunctioned 

 during the mission. Three of the Hasselbad cameras used Kodak 2405 film 

 with Wratten 2E and 47, Wratten 45, and Wratten 21 and 57 filters. The 

 fourth Hasselbad camera used Kodak 2424 black and white infrared film and a 

 Wratten 89B filter. The nominal transmittance of the filters used with the 

 Kodak 2405 film is shown in Fig. 3. On one flight, the four Hasselbad 

 cameras were replaced with a second RC-8 camera that was loaded with 

 specially manufactured Kodak SO-397 color Ektachrome film without the blue 

 sensitive layer. The submerged target was overflown with the aircraft 

 heading north. For control, a duplicate resolution target was laid out on 

 the beach so that the submerged target and then the beach target would be 

 photographed. 



RESULTS 



As expected, submergence depth was the most important factor affecting reso- 

 lution (Fig. 4). A careful examination of the data obtained from an altitude 

 of 2000 feet reveals that for the target on the beach, the light gray 1- by 

 3-foot bars, as well as the black 1- by 3-foot bars, were visible; but the 

 black 1/2- by 1-1/2-foot bars appeared only as smudges. At a 5-foot submerg- 

 ence depth, the black 1- by 3-foot bars were visible; however, the light gray 

 1- by 3-foot bars were not visible, the light gray 2- by 6-foot bars were 

 barely visible, and the black 1/2- by 1-1/2-foot bars appeared only as smudges. 

 At a 15-foot submergence depth, the black 2- by 6-foot bars were visible, and 

 the black 1- by 3-foot bars appeared as a smudge. At a 30-foot submergence 

 depth, one of the black 2- by 6-foot bars was visible, but no trace of the black 

 1- by 3-foot bars could be seen. At a 45-foot submergence depth, the black 4- 

 by 12-foot bar was still clearly visible. At a 60-foot depth, the target was 

 barely visible, and there was only an indication of the black 4- by 12-foot bar. 



A comparison of the effect that filter and color film had on resolution re- 

 vealed the following (Fig. 5): The target was submerged 30 feet. Except for 

 the view taken with the Wratten 25A filter, it was difficult to discern any 

 appreciable difference in the target resolution. When using the Wratten 25A 

 filter, the target at the 30-foot submergence depth could be imaged although 

 it was clearly visible at the 15-foot depth. A more critical comparison of the 

 filter performance by viewing the original negatives for all submergence depths 

 indicated that the image obtained with the Wratten 45 filter was slightly 

 poorer than the image obtained with the Wratten 2E and 47, the Wratten 57, and 

 the Wratten 21 and 57 filters. 



The images obtained with the specially manufactured Ansco D500 film, the 

 specially manufactured Kodak SO-397 color Ektachrome film, and the Kodak SO- 

 397 Ektachrome film, with the target submerged to 30 feet were compared 

 (Fig. 6) „ Comparison of the two films without the blue sensitive layer as 



VII-6 



