Underwater Digital Photography

From the Desk of David Pogue

Last month I took my favorite digital camera, the Canon PowerShot S45, on a trip to the Virgin Islands for a vacation with my family. What made the prospect so exciting was the waterproof camera housing that I borrowed from a friend for the week. (Well, OK, taking a trip to the Virgin Islands for a vacation with my family was sort of exciting, too.)

I've posted some of the results of my snorkeling safari at www.davidpogue.com/seapix. (I included a couple of above-water shots, too, so you can get an idea of the PowerShot's quality.)

The experience was more intense than I'd imagined. Just the mere act of submerging a $500 piece of delicate equipment into salt water made a small dent in my sanity.

Upon my return, I had some questions for Canon about the finer points of using its case. Canon directed to me to an amazing Web page, a guide to underwater digital photography on the Japanese Canon Web site (don't panic -- it's in English):

http://www.canon.co.jp/Imaging/uwphoto/index-e.html.

There I learned so many juicy pointers, I wanted to dash back to the airport for another vacation. For example:

* Digital cameras are ideal for underwater photography.

Because the murk of the water requires you to come in close to your subject, the ability to precisely preview your shot on the L.C.D. screen is essential. With a film camera, you're susceptible to parallax problems in which the eyepiece viewfinder, which is offset from the lens, misleads you into taking a slightly off-to-the-side shot.

* Sunlight becomes more diffuse the deeper you go, and different colors of the spectrum drop out at different rates, red being the first to go. So adjusting the camera's white-balance controls is essential. Use the Cloudy setting for deep dives, the Daylight setting close to the surface.

If all else fails, you can adjust the color later in a program like Photoshop.

* The built-in flash of a digicam makes all the little floating specks reflect right back at you, creating "marine snow." The only way to avoid it is to use an external underwater flash -- not something the average vacation-goer is likely to carry in the old backpack, to be sure.

* Underwater camera cases are ingenious -- all the key controls of the camera have corresponding, gasket-sealed pushbuttons on the outside of the case. But they're still not immune to the laws of physics. Even a hair or a grain of sand is enough to admit water on deeper dives. You're supposed to spend a great deal of time before and after each dive taking care of it, removing and inspecting the rubber O-ring seal, rubbing it with the supplied grease and so on.

* The camera's own moisture evaporates as the temperature inside the case rises, fogging up the inside of the case. Canon supplies anti-fog solution for the case's lens, but also suggests that you wedge, of all things, one of those little silica gel packs inside (of the sort that you sometimes find in grocery store condiments).

Another tip:

Load the camera into its case in an air-conditioned room, where the air is dry.

* The Canon site offers some almost giggle-inducing insight into the personality of your main underwater subject matter -- fish. Fish are, well, fish. They move quickly and they're easily frightened. Good tips include holding the camera at arm's length to avoid scaring the little guys, or, if you're scuba diving, approaching from underneath.

Underwater digital camera housings aren't cheap; Canon's costs about $160. (Actually, going halfsies with a friend or two is a great way to buy occasional-use items like this.)

But it opens up a whole new world of photographic possibilities, and lets you capture an intense underwater experience you'd otherwise have no way to remember -- except by remembering.