|General Underwater Photography
The majority of underwater cameras are made to shoot general photography. It doesn't involve much more than the camera itself. Various point-and-shoot cameras have a fixed focus at a specific distance. Therefore, the subject is sharpest at that focus point. With general photography, you can take pictures of underwater scenes, other divers, or both. Many of the compact cameras have a built in flash for convenience with a maximum distance is seven feet, but many manufacturers offer a more powerful flash as an accessory.
Successful photographs of fish photos can look great, but they are the most difficult to take because fish generally won't stay still and let you get close. In order to capture them on film, you will need stealth, knowledge of the fish, and most important patience. Some camera systems use gun sight viewers or light beams to let you know when the fish is in your frame of focus.
The main use for this type of photography is in capturing large marine life, shipwrecks, and divers. These types of lenses do not work well for smaller reef life as the subject gets lost in the background. You'll need a wide-angle lens for this type of photography. Also, powerful strobes are desirable because the field of view caught on film is greater and needs to be lit. Wide-angle photographs are best taken with wide-angle specific lenses. Wide angle photography has the benefit of enabling the photographer to get closer to their work, there by reducing the water column between them and their subject. A standard camera lens is usually between 28 to 35 mm and covers approximately 46 degree view. A wide angle camera lens will vary from 15 to 20 mm and the field of view for a 20mm is 80 degrees and a 15mm will cover over 90 degrees.
Extreme close-up or macro photography requires that you get the lens very close to the subject in order to form a large image on the film. This is the easiest and most vivid type of underwater photography. Most cameras have focus limits so you'll need an accessory to allow macro photography. Some of the point-and-shoot cameras come with a macro lens and framer system but you will need to use a flash to bring out the color of your subject. You will most likely get the best results shooting static coral and small creatures such as nudibranch at a range 0-18 ".
Color negative film is great for new underwater photographers, they feature a large selection of speeds and has offer wide exposure latitude. This means the film has an excellent margin in its ability to give a correct exposure despite varying levels of light. In other words, you'll get a good picture, even if your exposure wasn't quite right.