Some Basic Rules for Underwater Photography
Make sure your camera is protected from the water, in a submarine housing, if it is not an amphibious camera like an Olympus TG4.
Get Close - Then Get Closer Still!
Water also upsets the sharpness of your pictures because it is never optically clear. Reduce the amount of water between you and what you are photographing to a minimum by getting as close as you can. This means using a wide-angle or fish-eye lens or an extreme close-up macro lens for sharper clearer pictures.
Water absorbs light selectively. Red light is absorbed first, followed by green and then blue light. This means, the deeper you are the more the daylight is filtered blue by the water.
You can counteract this in different ways.
- Stay very shallow.
- Stay shallow and use a filter to remove the excess blue light.
- Adjust the colour sensitivity of your camera’s sensor by ‘white-balancing’ subject to there being enough red light penetrating to the depth you are at.
- Take some independent white light of your own.
Portable white light comes in two forms:
Video Lights provide a continuous light source. The brightest video lights can also be used for close-up still photography. They have the advantage that you can see immediately the effect they produce. They have to produce a perfectly even daylight-colour light and their output is rated in LUX.
Electronic Flash (called strobe in America) can produce a far greater amount of light but only in a very short burst. This has the advantage of freezing the action for very sharp pictures but it takes practice to anticipate the effect. You need to synchronise the flas so that it can be triggered by the on-board flash of your camera but at the same time you need to be sure that light from the on-board flash does not leak out and spoil your pictures.
Backscatter occurs when the detritus in the water in front of your camera is lit up by either your video light or flash. To avoid that, position your light a long way from the optical axis of your camera lens. The most convenient way to do this is to mount it on an arm that is fitted to your camera tray. The wider the angle-of-view of your lens, the further the light should be from the lens or the longer the arm needs to be. Avoid positioning a light ahead of a wide-angle lens.
Balance the foreground light that will be in full colour with the background lighting to obtain a natural effect. The shutter speed only affects the constant light whereas the f/stop setting and ISO setting affect the overall exposure. Don’t be afraid to practise. Shoot RAW files that can be adjusted in your home computer afterwards.