:: 02. Marine Techniques

Despite the advantages digital cameras bring to underwater photography, you do need to take note of a few differences between shooting on land and underwater. For example, light gradually becomes more diffuse the deeper you go underwater until you eventually end up in a completely blue world. To shoot colorful pictures at each depth, you need to compensate by employing supplementary light sources, such as flashes or underwater lights, or by using the white balance features of your digital camera.

If you use the camera's built-in flash underwater, you may also experience the –marine snow phenomenon” where light reflects off plankton and sand particles in the water to create a haze over the entire image. You can avoid this by using an external flash or video light instead of the built-in flash for underwater photography. The exception is close-up macro shots where there is a relatively thin layer of water between the subject and the camera.

Also note that zoom settings behave differently underwater because light refracts at the boundary between air (in the lens) and water. This principle can be demonstrated by the bent appearance of a hand half dipped into a water glass. The same zoom setting on land will result in a narrower field underwater. To shoot wide angles, therefore, you must shoot the subject from a slightly greater distance than you would on land.

These techniques will soon become second nature to you if you use the digital camera's endless photo capacity to learn by trial and error. Once you understand the differences between shooting on land and underwater, you can easily adapt to taking great underwater pictures. In the process, you can expect your digital camera to become a trusted partner in your diving adventures.

Oh, there's one more difference between shooting on land and underwater with a digital camera, don't forget to put the camera in the waterproof case before submerging it. It isn't waterproof by itself. Place it in the waterproof case, then close and lock the cover. Before embarking on each dive, remember to inspect and service the waterproof case. That way your underwater photography will always give you great results and be a pleasurable experience.

White Balance Adjustment
Whereas there is no color bias on land, light is diffused underwater so that the red spectrum appears darker. The deeper you get, the greater the diffusion effect, and hence, the greater the change in colors. Use the white balance feature to achieve natural coloration
Flash Related Marine Snow Phenomenon
The –marine snow phenomenon” is likely to occur when a built-in flash is used to shoot a subject at a standard portrait-shot distance. Use an external flash to avoid this problem.
Different Angle of View
When subjects on land and underwater are shot at the same distance with the same zoom setting, the underwater subject will appear larger in the image. This is a result of the angle of view being narrowed by refraction. Back up or expect a narrower angle underwater.

This section has been extracted from Canon Japan on how to prepare your digital investment.

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