76 PHOTOGRAPHY
port and the flat port. The dome port requires little focus
adjustment once set, and the lens behind it retains its focal
length under water. A flat port will need focusing all the
time and it will act as a magnifying glass, increasing
the effective focal length of the lens behind it by around
25 per cent.
Digital cameras can be put in housings with wide-
angle adaptors and external flashguns as optional extras.
Digital-camera housings usually have diffusers to tone down
the light from the internal flash and alleviate problems of
backscatter under water, due to the flash’s proximity to
the lens. They are ideal for use under water due to some
of the advantages mentioned under digital photography,
particularly the opportunity to review the images as they
are taken. However, their main disadvantage under water
is shutter-lag, which is more pronounced because of the
difficulty of holding the camera still until the shot is
taken. This becomes a particular inconvenience when
trying to photograph an action shot. Lenses in compact
digital cameras often suffer from severe distortion, espe-
cially at wide-angle settings. Wide-angle adaptors usually
have to be re-fitted under water, to allow water in and
air bubbles out, between the lens and the adaptor. The
lens of a digital camera should also be inserted into a
small tube of neoprene to mask light around the lens
where it sits in the housing. The top end of the digital
market is the digital SLR with associated expensive
housing, interchangeable lenses, dome ports and power-
ful flashguns. For high-quality images, there is nothing
better; they offer high-quality lens optics and minimal
shutter-lag.
Underwater Photographic Techniques
Diving technique: Perfect buoyancy and fin control
are essential techniques to master so as not to disturb the
visibility. As part of the daily project briefing, other team
members should be informed of the intention to take
underwater photographs. Ideally a period of the day
should be devoted exclusively to photography, with no other
divers in the water. This could either be first thing, before
the silts are stirred up, at slack water, or around midday
when natural light levels are at their best.
Equipment care: Before and after entering the water,
check the equipment for bubbles and leaks. Refit wide-
angle adaptors under water. After diving rinse the equip-
ment in fresh water.
Photography techniques: Do not punch the shutter-
release when taking a photograph – “squeeze” it gently
to avoid camera-shake. Shoot within one-third of exist-
ing visibility.
Cleaning: Carefully clean ship’s timbers and tidy up the
excavation area before photography.Composition: This is very important with respect to the
type of shot – with and without a scale, with and with-
out a diver. Try shots from different angles to obtain the
best angles to show the subject. Distinguish between an
artefact record and a public-relations shot, as each needs
different treatment. Wait for the diver’s bubbles to prove
the shot was taken under water. Occasionally an obliging
fish swims into shot, which can produce a dramatic shot
of a diver working with bubbles and marine life.Aiming the flash: The correct positioning of the flash
is one of the most important factors for taking a successful
underwater photograph. To avoid backscatter, move the
flash further away from the camera, this avoids illuminating
particulate matter between the lens and the subject. Hold
the flash above the subject and to one side, as shown in
figure 10.5. Think of the flash as mimicking the sun. One
technique with a powerful flash is to put it on a pole to
extend the flash-to-subject distance and better mimic the
sun. When following the table of settings for the flash,
remember that it is the flash-to-subject distance that is
needed for the correct exposure, not the camera-to-
subject distance.Figure 10.5 Lighting, composition and scale are all impor-
tant considerations when making a photographic record of
a site. (Based on original artwork by Ben Ferrari)