TECHNICAL ASPECTS OF DOME-CORRECTOR-PORTS 

 AND FLAT -PORT OPTICS IN UNDERWATER PHOTOGRAPHY 



Flip Schulke 



Black Star 



450 Park Ave. So., New York, N.Y. 



Frank Pugliese 



General Electric Co. 



Philadelphia, Pa. 



Robert Farrelly 



Underwater Explorers Club 



Freeport, Grand Bahama 



ABSTRACT 



By testing both underwater cameras and housings, fitted out with 

 flat-port and dome-corrector-port "windows," on a direct lens, 

 distance, F-stop, test pattern test, we found dome-corrector- 

 ports did increase edge sharpness, and corrected refraction mag- 

 nification. We documented the slight differences between domes 

 of 3, 5, 6, and 8 inches. The 8-inch dome gave the best test 

 results, though differences between the various smaller domes 

 versus the 8-inch dome were not significant. 



OBJECTIVES 



Because of time constraints and lack of constant water clarity, some of our 

 original objectives were not accomplished in the 6 days of our mission. 



We had planned on the underwater testing of various commercial brands of color 

 films, on the same color-test pattern, for color rendition and color saturation. 

 We also had planned on testing various underwater fLash and strobe lights for 

 color balance. 



We began testing in all these areas but saw that the limited time within the 

 habitat would not permit us to make equal comparison tests in all these aspects 

 of UW photography. In addition, the water clarity varied during our mission. 

 We decided to concentrate on the last objective, that being the on-site, empir- 

 ical testing of various lens, cameras, and housing combinations. Our primary 

 interest was in getting photographic test pattern evidence, in black and white, 

 to confirm or deny conflicting optical theories of spherical-ports versus flat- 

 ports as correcting lenses. 



One of the major problems in underwater photography has been the cost of the 

 equipment needed to do the job. It was our objective to compare inexpensive 

 lens corrector systems, represented by the spherical, hemispherical or what is 

 commonly known as "dome-port" correctors. Our hypothesis, reinforced by our 

 regular UW photography, was that for practical purposes, these "dome-correctors" 

 would give results which would enable photographers to overcome the inherent 

 problems of the plane or flat-port. 



VI-295 



