Q: Do I need to be a good diver to take UW photos?

A: You don't necessarily need to be a good diver to take underwater photographs, but we have, in the past, received calls from people who don't realise that they won't be able to see underwater until they get a diving mask In general, you can take photographs from just under the surface with only a mask; but a mask, a snorkel, and a pair of fins will make the job easier and enable you to make brief forays to a depth of a few metres. There are also numerous situations in which, to make an engaging or dramatic photograph, it is necessary to be at the same depth as, or deeper than, the subject; in which case, basic mastery of breath-hold diving is essential. Breath holding has its limitations however, particularly because it gives little time for good choice of composition, which is why photographers trained in the use of SCUBA (Self-Contained Underwater Breathing Apparatus) will generally use it even at the shallowest of depths. Scuba equipment, incidentally, has come a long way since the days of the pioneers and can now be regarded as an ordinary form of transportation technology, like a car; which can be used by nearly everyone, but which requires a training course and an exam to establish basic competence.

Q: What makes a good photograph?

A: A photograph doesn't have to be particularly 'good' if all you want to do is evoke memories of a particular holiday or experience in your own mind. It needs to be 'good' in some sense however if you want to evoke a comparable emotional response in someone else, or if you want to be regarded as sufficiently expert to warrant publication of your work. The question then arises as to what defines a such a 'good' photograph, and the answer is by no means clear-cut. In any art, there are always groups of bad practitioners who club together to give each other prestigious awards. It follows that what is good depends on the context, and in certain contexts, bad is good. If you agree that the medium is not the message however; a good photograph is one which takes the viewer's mind beyond the paper or the video screen and into another world, and the matter of achieving this effect is often more technical than artistic. In other words, unless there is some hidden agenda, a photograph should be as sharp, well-lit, and well-composed as you can make it. As a beginner, you can expect to take some good photographs by accident; but your objectives should be firstly: to train yourself in recognising when the necessary criteria have been met, and secondly: to develop techniques which enable you to meet those criteria reliably.

Q: How do I learn to take good photographs?

A: It is not possible to become a good photographer instantaneously, simply by reading books and manuals. The more you read around the subject the better; but real learning occurs on an emotional level; which means that you must practice the art as much as you can, and make sure that you can remember and repeat the techniques and equipment settings you used to obtain a particular result. We learn by doing things, seeing the results, getting other people's reactions, and doing more things. It follows that the key to good photography is feedback, and it is also true that the more direct the feedback is, the better is the learning experience. One way to get feedback is to go on one of the various underwater photography courses which are offered by diving organisations, private individuals, and some universities. Another is to join an underwater photography group. The learning process however, is largely self-driven, and if you want to be good at photography, you can start by observing the following points:
Know your equipment: read all the manuals from cover to cover and make notes on a diving slate of the points you can't remember. Also read around the subject and learn about basic photography - f-stops, guide numbers, depth of field, etc.
Get other people's opinions on artistic aspects of photographic technique, but don't take them too seriously - find your own style and be suspicious of photographers who prefer 'special effects' over technical perfection.
Take lots of pictures: The old standard used to be one 36 exposure film per dive.
Minimise the time between taking the photograph and seeing the result. This is not such a problem with digital and video cameras, but remember that you can't tell much about a photograph by looking at a tiny LCD screen. For film cameras, make liberal use of the one-hour developing service.
If you can afford it, use an artificial light source separated from the camera. All natural waters contain suspended particles, and the main point of using an external light or flash is to illuminate the subject without illuminating the suspended matter between the subject and the camera lens.
Use wide-angle or close-up lenses, i.e., try to take underwater photographs from the shortest possible range. This minimises the amount of cloudy water in front of the subject, and minimises the blue colour cast which will be added to the light from your source of illumination.
Study the subject: Marine animals won't pose for you, but if you study their behaviour you can often work out where to position yourself to get a good picture. Getting a good picture also sometimes involves staying still for long periods, which means that you will need a diving suit which keeps you from feeling cold.
Experiment with perspective: An proper understanding of perspective is the lost art of photography. This is largely due to the widespread availability of zoom lenses, which encourage the user to turn a knob to fill the frame, rather than adopt the correct focal length and camera position for the type of photograph being taken. The appearance of a picture depends very much on the camera position, and although the choice is a matter of style, photographs are usually most dramatic and engaging when the camera is on the same level as or below the subject. In some cases, it is impossible to get the camera into a good position and still see into the viewfinder, in which case, it is important to remember that use of the viewfinder is not compulsory, you can also estimate the composition (with a little room for cropping), and take several shots to be sure.
Imagine the end result: Look carefully at the image composition in the viewfinder. Does background clutter make the image incomprehensible? Have you spoiled the picture by cutting off bits of the subject? Is the horizon level in the frame? As the person sitting in a room watching a slide-show must imagine swimming across a reef; you, swimming across a reef, must look into the viewfinder and imagine sitting in a room watching a slide show.

Q: How do I get sharp, brightly coloured underwater pictures?

A: Even professional photographers make the mistake of thinking that the rules that apply when working in air will be equally good underwater. Such assumptions will let you down badly because, unlike air, water absorbs light strongly and modifies its colour, it scatters light because it contains suspended particles (fog), and it modifies lens behaviour because its refractive index is different to that of air. Assuming that you control the lens issues so that you can actually focus, you should modify your working practices as follows:
Unless exceptional subject matter indicates differently, you should work from the shortest possible range and use a local light source (i.e., flash). As a good starting approximation, light absorption reduces the effective guide number of a flash by a factor of 3. (e.g., a strobe with a guide number of 24 in air becomes a strobe with a guide number of about 8). The water also acts as a filter with a density of about 0.12 red per metre of light path; which means that you lose a whole stop of red for every 2.5m, and since the light must travel from flash to subject, and then from subject to camera, you lose 1 stop of red when you are only 1.25m away from the subject. Consequently, you aren't going to get highly saturated pictures unless you are considerably closer than that, which means that you should use either a wide angle or a macro lens.
If your camera allows it, record your pictures in a 48 bit-per-pixel mode (e.g., RAW). This allows colour balance and histogram (black point, white point and contrast) adjustments to be made after the event without significant loss of quality.
Use an external flash on an articulated lighting arm. The water will always be (at least) slightly foggy. You should therefore aim the flash and camera from different directions in order to minimise back-scatter.
When shooting by natural light, use manual white balance (camera permitting). Take a white slate with you for use as a white balance target, and make a WB adjustment for every change of depth or lighting conditions. An underwater colour correction (UWCC) filter may help if extreme WB adjustments are required.

Q: How do I do half-in half-out shots?

A: Firstly, you will need a lens which can focus in both air and water; and since the required focus settings will be different in the two media, you'll need to choose lens and ISO speed with a view to obtaining a very good depth of field. This means that you'll probably end up using a wide-angle lens, but you cannot use the underwater-only Nikonos and Sea & Sea Lenses. The awkwardness of catching exactly the right moment as the waves lap up and down also favours the use of a camera with low shutter lag.

If you decide to use an SLR, you have a choice between using a flat port and a dome port, and the results will be quite different in each case. If you use a flat port, the underwater part of the image will appear magnified relative to the above-water part. This effect is generally considered to be undesirable.

50mm lens with flat port

If you use a dome port, with the lens correctly positioned inside it, the relative magnification above and below water will be the same; but the problem of obtaining sufficient depth of field will be much worse. Above water, the dome has minimal optical effect; but underwater it acts as a strong concave lens, producing a virtual image a short distance in front of the main lens. The depth of field must be sufficient to produce acceptable sharpness from both this very close virtual object, and the normal subject above water. The best bet is therefore to use a wide lens (e.g. 20mm) at a small aperture. Note also that the proximity of the virtual object is a function of the dome radius: a larger radius puts it further away from the camera, so it helps to get the largest possible dome port. If the main lens needs a supplementary close-up lens to make it focus behind the dome underwater, satisfactory half-in half-out shots will not be possible.