Shutter speed. The amount of time the camera shutter opens to permit light through the aperture and on the image sensor.
Fast shutter speed (125/sec and above) will stop action. Slower than (60th/sec) will be blurry, unless the camera is held very steady or on a tripod. As a general rule, use shutter speed values between 1/90 to 1/500 for underwater.
Backscatter: Fine particles of sand or plankton suspended in the water that appear as small dots in your picture. It looks like it’s snow- ing in the water. Move flash head as far away from camera lens as pos- sible. Direct outer rim of flash beam at your subject, so you do not illu- minate the water between the camera and the subject.
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