There are lots of good sites on the internet giving details of techniques in underwater photography and information on these can be found on the Links page. This article is intended for those quite new to underwater photography to pass on some points I have learned which may be of help.
The essentials of U.W.Photography are:
1. Get as close to your subject as possible. (This minimises loss of the red
end of the spectrum and light scatter due to suspended particles).
2. Ensure your subject is correctly focused.
3. Ensure exposure settings are correct.
4. Ensure shutter speed is sufficient to avoid camera shake or movement by the
subject.
The major choice regarding equipment is whether to take the 'rangefinder' route (Sea and Sea Motormarine II or Nikonos) or to go for an SLR in a housing. 'Rangefinder' cameras are more compact to handle but for versatility you can't beat an SLR system, especially for closeup work. There are now a number of housings for digital compact cameras becoming available and although not comparing with SLR's for 'serious' work, may be worth considering. The ability to use the LCD viewfinder and autofocus make them more viable for closeup work and there are new specialist 'slave' strobes to overcome the problems associated with using the cameras built in flash. I am sure we are going to see a lot of developments in this field in the near future.
Having previously used a fully manual system (manual focus and exposure) I
can assure you that TTL flash exposure is a great help, you just have to make
sure you are in the correct distance range for the aperture setting and after
that the system usually does an excellent job of looking after itself.
The autofocus of an SLR system also greatly increases success rate with close
subjects, especially fish which may be constantly on the move. With manual
focus make sure you know the distance from the camera to the outstretched
fingers of your arm (about 18ins) and use this as a guide in setting your
focus. N.B. remember that your lens focuses on the apparent distance of an
object not the actual distance and this is about 25% closer (i.e. about 13 ins
for an outstretched arm). Practice with a test film!
With a simple camera system or one using manual exposure it is best to use a
'Print' film rather than 'Slides'. This is because the exposure latitude of a
'Print' film is a lot greater i.e. it will tolerate more over or under
exposure.
My present camera system, which was used
for the photographs in the main article, is a Nikon F70 in an Ikelite SLR-AF
housing, this is polycarbonate and allows visual inspection of what is going on
inside, as well as being relatively inexpensive. (I would like a Subal system
but they are a lot more money).
The main flash is an Ikelite Substrobe 100A on a' ball and socket' arm. For
close-up subjects I also have a Sea and Sea YS30 slave strobe (this has no
cable of its own but fires when the main strobe fires and quenches when the
main strobe switches off i.e. all in TTL mode). A slave strobe helps reduce the
harsh shadows that can result from a single strobe.
Lenses are a 28-80mm Nikkor zoom and 60mm Micro Nikkor both used with a flat
port and a 17mm Tokina ultra wide angle used with a dome port.
Film used for most of the
shots was Fuji Provia 100F (slide) this is very fine grain and the extra speed
gives a little more flexibility over the usual favorite, Velvia. Some of the
wide angle reef shots e.g. 'Red soft corals' were Kodak Elitechrome ISO 200.
(For the wreck shots I should have used a ISO 400 film as many were
underexposed despite use of full aperture).
*Flooding is always a worry and one tip I read is to place one or more 'Tampons' (extra absorbent) in the bottom of the housing. It won't save a major flood but will mop up a minor leak or give you a little time to get the camera out of the water. Panic if you see a stream of bubbles coming from the edge of the port or back of the housing!!
In the clear waters of the Red Sea I found the zoom lens to be my favorite
as it gives the flexibility to photograph a wider range of subjects on a single
dive. And underwater time is precious when you are out there! (The 28-80mm will
focus down to about 1:4 reproduction on 80mm setting, so is O.K. for semi-macro
work. At the wide angle setting it vignettes in the flat port due to the lens
barrel being near its shortest length and thus back from the front of the port.
35mm is the widest usable setting.
The 60mm Micro is an excellent lens and will be used a lot in U.K. waters where
most of my photography is close-up. However on autofocus it can spend a long
time focusing due to the very long 'travel' of the lens. It really needs to be
used in manual mode but I like the convenience of autofocus.
The 17mm is an impressive lens but needs a lot more care and skill to get good
results, I have a lot to learn! Remember most strobes have a smaller field of
illumination than the view of the lens and can only be used to light subjects
in the foreground. Best results tend to be achieved in shallow water where
there is more light but much of the background is still going to be blue due to
the horizontal distance of water.
Any comment or questions please contact lance.peters@btinternet.com
Here are some links to good sites on Under Water Photography:
scubafest.org
underwaterphotography.co.uk
exploreuw.com