Take Your Digital Camera Under Water, Part II

Tricks of the underwater trade: managing color, avoiding backscatter spotting, and more.

Dave Johnson

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Feature: Take Great Underwater Pictures

There are some experiences that words simply cannot adequately describe. Take, for instance, what happened when I went diving off the New Jersey coast a few years ago. "Watch out," the boat's dive master warned. "You may see a few jellyfish on this dive." In reality, I descended through hundreds, perhaps even thousands, of 5- or 6-foot-long jellies. They were everywhere as far as the eye could see. They moved through the water like a roaming herd of translucent buffalo. It was one of the most surprising, amazing experiences I ever had under water, and thankfully I had a camera with me to freeze the moment forever.

Last week, I talked about how easy it is to add an underwater housing to your digital camera. This week, let's focus on taking good pictures down there. After all, photographing in water poses some unique challenges you won't find on dry land.

Where'd the Color Go?

The first time you take your digital camera under water, you might be disappointed by the lack of color. Everything comes out in shades of blue. Unfortunately, color is readily absorbed by water, and the deeper you go, the more pronounced this effect becomes.

If you're shooting in very shallow water--say, while snorkeling or skin diving--then you won't notice much loss of color. But by the time you get past 10 or 15 feet of water, red is absorbed by the water since it has the longest wavelength. Your pictures start to take on the hue with the shortest wavelength: blue. One solution is to adjust the white balance of your camera.

If your camera has white balance presets, choose "cloudy" or "shady." And when you have a choice of how to frame your picture, you should point the camera slightly upwards instead of downwards. Pointing it up increases the available light and reduces the amount of blue in the shot. For the best color reproduction under water, though, you'll want to use a flash.

I See Spots!

As soon as you start firing a flash under water, though, you get the bane of underwater photographers: backscatter. The problem is that water isn't as clear as air. It's filled with floating particulates. When you fire a flash, the light reflects off of all that dirt in the water and some of it invariably shows up in your pictures, looking kind of like snow.

So how do you avoid backscatter? There are a few solutions. If all you have is the flash that is built into your digital camera, only use it to shoot subjects that are very close. The more distant your subject, the more likely that you'll get backscatter in your pictures. A more expensive alternative is to add an external underwater flash, usually called a strobe. A strobe, typically mounted at the end of a bendable arm, avoids backscatter by getting some distance from the lens so that the light doesn't reflect straight back at the camera. If you're looking for a strobe, I highly recommend starting at Sea and Sea.

Getting the Best Shots

Then there's the question of when you should take your camera under water. You probably know that I often say that the best hours to take pictures with your digital camera are in the morning and late afternoon, avoiding the directly overhead sun. Well, underwater photography requires exactly the opposite shooting strategy: You'll get your best shots when the underwater environment is at its brightest. That means, of course, the hours around noon. When you shoot with the sun overhead, it penetrates the most deeply under water, giving you the ability to shoot with faster shutter speeds and get better color in your pictures.

Don't over-use the zoom while you're down there. Remember that water acts like a magnifying glass, and that means your camera's zoom will have even more reach than it does on the surface. Digital cameras tend to have rather limited wide-angle capabilities to begin with, so taking one under water further reduces the bottom end of the zoom range. That's why I rarely zoom in much with my digital camera under water; I find the wide-angle position captures the pictures I most want to see.

Dave's Favorites: The World's Biggest Panorama

Step right up and prepare to be amazed. That's because what I've got for you this week will amaze and astound you: the world's largest stitched image, a panoramic photo that's over 1 gigapixel in size!

I was duly impressed when I visited the Tawbaware Web site and found "Breaking the Gigapixel Barrier."

The photographer, Max Lyons, set out to make a digital image with over a billion pixels, and his resulting 40,784-by-26,800-pixel image is staggeringly detailed. His photo of Bryce Canyon National Park in Utah consists of 196 separate photographs taken with a 6-megapixel digital camera, made over a 13-minute time period. Lyons stitched the frames into one seamless composite using a program called PTAssembler, which is available for download from the Tawbaware site.

There's a lot of detail on the page about the who, what, why, and where of the panoramic stitching process that Lyons employed, and you can even download a full-width (but only 100-pixel high) crop of the image to get some perspective on just how amazingly huge it actually is. My favorite part: He includes a side-by-side comparison of a segment of the panorama at various megapixel levels, so you can see the value of the extra resolution afforded by cameras with higher-quality sensors.

Q&A: How Long Do Digital Pictures Last?

I have heard many conflicting statistics about the life span of pictures printed at home. Is it true that they will not last more than 4 or 5 years, even if protected by glass? Someone also told me that it is not the paper, but the ink that matters. Another digital camera buff said he prints his pictures on his computer, but then reprints them at a store that claims the prints will last a lifetime. And I recently saw that Kodak claims its paper will last 100 years. At this point I am so confused. Help!

--Rhoda Kirk, Chicago

I don't blame you, Rhoda. This print stuff is perplexing. Let's try to make sense of it.

There's a bit of truth in everything you wrote. The lightfastness--or ability of a print to withstand fading due to exposure to light--depends upon both the ink and paper, which work together. Manufacturers design ink and paper as a team so that the ink penetrates just the right depth into the paper. Sink too far, and the colors won't be vibrant. Don't absorb deeply enough, and the ink is ravaged by ozone and ultraviolet light. That's what you lose when you buy cheap replacement ink instead of the real deal from Epson, Hewlett-Packard, or however made your printer.

Older printers definitely had a 5-year limit on prints: Their inks weren't engineered with lightfastness in mind. Most modern ink jet printers advertise 5- to 20-year print life span, though some popular models promise 50, 90, or even 200 years.

And don't forget that there are two kinds of ink out there: Dye based and pigment based. Dye-based inks are what's used by most ink jet printers, and they tend to last anywhere from 5 to 20 years on average. Truly archival-quality inks are usually pigment based. Pigment inks can last 100 to 200 years, which is many times longer than what you even get from traditional film camera prints. The downside is that most people find that pigment inks aren't as bright and dynamic as prints made from dye-based printers. On the upside, in some cases, they should be able to last several lifetimes.

The bottom line? Shop carefully for an ink jet printer, keeping an eye out for lightfastness ratings. Then use the recommended ink and paper to get those results. Companies like Epson and HP sell a number of printers that make prints that will outlive all of us.

For more information, check out a PC World article from October 2002, "The Fade Factor." Not all of the products mentioned in that article are still current, but I think that you'll find there's a lot of good general advice about matching papers, inks, and printers.

Hot Pic of the Week

Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique. Every month, the best of the weekly winners gets a prize valued at between $15 and $50.

Here's how to enter: Send us your photograph in JPEG format, at a resolution no higher than 640 by 480 pixels. Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering, please read the full description of the contest rules and regulations.

This Week's Hot Pic: "Trees," by Jack Simmons, Norfolk, Virginia

Jack used a Kodak DX4530 to capture this engaging portrait of a lonely pair of bare trees against a gray sky. He says that he adjusted the tint and color levels with Microsoft Picture It Express.