56 UNDERWATER GUIDE TO MARINE LIFE 



of fishes and most marine animals (about one twenty-fifth of a second) is faster 

 than that of humans. This means that if a photographer and a fish sight each 

 other at the same time, the fish could be at least halfway turned around and 

 headed away before the photographer raised his camera. 



The 35mm. camera is widely accepted as the camera best suited to underwater 

 work. Both camera and case are small and easy to handle. It takes a thirty-six- 

 exposure roll of film, enabling the photographer to take fewer trips to the surface 

 to reload. Some 35mm. cameras have bulk loading attachments which take up 

 to four hundred frames. There are 35mm. cameras available which have a 

 spring mechanism that transports the film and cocks the shutter, leaving only 

 the trigger release to be pressed for rapid sequence exposures. The Praktina 

 Cfig. 14} and Robot meet all these requirements. 



Movie Cameras — For Underwater Use 



When selecting an 8mm. movie camera, one should: 



1. Select a camera with an f/1.9 normal and f/2.5 wide-angle lens. 



2. Select a camera which has the longest film run possible on one winding 

 (e.g., 10 feet). Long scenes are effective, short scenes are meaningless. 

 A long film run cuts control manipulations and allows concentration on 

 the subject. A good example of such a camera is De Jur (/ig. J4). 



3. Select a camera you know won't jam in the middle of an important scene 

 necessitating a trip back to the boat to clear a jam. Jamming is time- 

 consuming, troublesome, expensive, and results in the loss of previously 

 exposed film. 



The factors which determine the selection of a good 8mm. camera for underwater 

 work also apply to the 16mm. camera. The 16mm. camera should load the 

 largest footage possible; short footage cameras mean many trips to the surface 

 and loss of opportunities. Many of the professional photographers use motors 

 attached to their 1 6mm. cameras to eliminate hand winding. 



The Use of Wide-Angle Lenses Under Water 



With both motion-picture and still cameras, a wide-angle lens is necessary 

 when one wishes to encompass larger subjects without having to shoot at great 

 distances. 



Because of the refraction of light through glass, air, and water, objects under 

 water appear one-third larger or underwater distances appear one-fourth less. 

 This affects the goggled eye as well as the camera, making it necessary for 

 the photographer to back off farther to fill the picture frame and to set the 

 focusing scale at 75 per cent of the actual distance. The wide-angle lens helps 

 overcome this by permitting the camera to be taken closer to the subject. The 

 lens offers another advantage in that it has a larger depth of field, which means 

 one can shoot almost without chanoing focus. This is highly desirable, consider- 

 ing that most underwater pictures are taken at a low light level which calls for 



