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Underwater Photography Primer
Strap some tanks on your back and dive. In theory, if you take your pathetic Action Touch with you it
will be crushed by the water pressure. In practice, people say that Nikon overengineered the product so
that it can withstand quite a bit more than its rated 10 feet of pressure. I wouldn't take it beyond 30 feet.
The cheapest way to take pictures while SCUBA diving is by putting your standard camera into a plastic
bag. A plastic bag?!? Not just any plastic bag. A thick German plastic bag made by ewa-marine with a
metal screw-down zip-loc top. These ewa guys make plastic bags for cameras ranging from regular P&S
to SLRs with various combinations of lenses and flashes.
I have some ewa-marine bags. To my amazement, they do not leak.
However, I've never been able to use them successfully. The last
time I tried the ewa bag was on a liveaboard trip to the Great
Barrier Reef. I stuffed a Nikon 8008, SB-24 flash, and 60 macro
lens into the bag. As soon as I got to about 30 feet underwater, the
bag was pressing up against the camera to the point that the
controls were inoperable. The AF drive wasn't strong enough to
rack the lens out against the pressure of the bag. I got a few
snapshots but they were mostly pathetic in quality. Oh yes, with
my 20mm lens there was pronounced vignetting from the housing (example at right).
Now that we're deep
Oh yes, now that we're deep underwater, let's talk about
fundamentals rather than gear for a moment. One fundamental fact
is that water magnifies. Thus you end up needing a wider angle
lens than you thought. A 20mm lens is not especially wide for
underwater use.
If you have a longer lens, why not just back up? The problem with
backing up underwater is that water tends to absorb red and yellow
light. The more water between your subject and your lens, the
bluer your subject will be. If your light source is on your camera (i.e., if you are using a flash), every
extra foot of water between you and your subject addings two feet worth of bluing (one as the light goes
from the flash to the subject and one on the way back to the lens).
Underwater photographers are thus very fond of very wide lenses and very powerful flashes.
Back to the Gear
http://www.photo.net/underwater/primer (4 of 23)7/3/2005 2:18:13 AM