Most professional photographers remember their epiphany, the "eureka" moment when they first knew that photography would be the passion that would define their career. Mine came in graduate school when I was taking my first course in black-and-white photography. Seeing the image on that very first sheet of 8-by-10 paper gradually emerge in the Dektol bath beneath the darkroom's safelight inspired me. Soon, Ansel Adams' The Negative became my bedtime reader and my mind's eye saw the world in blacks, whites and shades of gray.

For optimal control in converting a color image to black and white, use Photoshop's channel mixer.

But then I went under water. The electric hues of tropical fish cried out for color film, and my vision was far more influenced by Ektachrome (and later, Velvia) than by my trusty Plus-X. Lately, however, I've begun to revisit black-and-white photography, and found that the images can capture aspects of the underwater world that color photography can't. With black and white, you can create a mood, an ambience and a stark power.

Even if you don't have your own darkroom or familiarity with the craft, it's possible to capture high-quality black-and-white underwater images. There are two easy ways to do it: either shoot black-and-white film or convert color digital images to black and white.

Standard black-and-white negative films are best for darkroom enthusiasts who process negatives and then print via a conventional enlarger in a home or commercial darkroom. Kodak, however, makes a black-and-white film that can be processed in any lab that does C-41, the chemistry used for normal color photos. Known logically as "Kodak Black and White" film, this emulsion contains dye couplers balanced to produce a neutral gray or black when printed on conventional color negative papers. The film is processed normally, like any other color negative film, and then printed on conventional papers. Any one-hour lab should be able to process these black-and-white images, and because the film is a 400 ISO negative film with considerable exposure latitude, it is very forgiving in terms of capture variables.

Because few labs have much experience working with this film, it can be hard to get a good neutral black. Until you shoot enough of it to get your local lab up to speed, this might be challenging. These negatives can be printed on traditional black-and-white papers for those who want control of the final print, but don't want the hassle of processing the negatives.

Agfa makes a black-and-white transparency film known as Scala. While it can be processed in only three labs in the U.S. (see www.agfa.com/photo/products/professional/film/scala/labs), it does have the advantage of being a slide film, delivered in normal cardboard 35mm slide mounts. It can be projected like any other slide film, and it can be scanned for printing like any other slide film. Because the slide is the final product, you don't have the level of darkroom control you find with conventional black-and-white films. This can be a blessing or a curse depending on your personal passion for darkroom tasks. I find Scala is a little low in contrast for many underwater subjects, but that can be enhanced by selective application of strobe light, or contrast control in processing. Underexposing and overdeveloping will enhance the contrast of this film, and so exposing this 200 ISO film as if it were 400 ISO, and then asking the lab to push it one stop, may give a better result for most underwater scenes.

Converting Color Digital Images

This color digital capture was converted to black and white using Photoshop's "desaturate" tool.

When I first began capturing digital images under water, I was very excited about the black-and-white setting on my Nikon D1X. In fact, one of my early digital shoots was at Grand Cayman's Stingray City and I proudly sent a CD of those images to one of my friends at Nikon. He was very supportive, but told me the black-and-white setting on the camera was intended more for recording lines of text, and that I would be much better off shooting in RAW, capturing all the information possible in the scene and then converting later in Photoshop. Not only would I get a bigger and better file, I would have the time to refine the file, and, more significantly, have the option of using the image in either black and white or color. Obviously, any image to be converted to black and white in Photoshop can originate directly from a digital camera, but can also be from a scanned color slide, color negative or even a black-and-white negative. However, not all methods of Photoshop conversion are the same.

QUICK AND EASY NO. 1: Probably the easiest way to get a black-and-white file in Photoshop is to open the image and then go to: Image > Mode > Grayscale. The software will ask if you want to "discard color info." Click OK, and a black-and-white image will result that can then be enhanced with levels controls and the brightness/contrast sliders (both accessible via the Image > Adjustments controls). You'll notice that the file size is significantly smaller because a great deal of information is thrown out, but it is easy and fast, especially if it is intended is for web use where big files are not necessary.

QUICK AND EASY NO. 2: To preserve a larger file, it may be preferable to open the file and then go to Image > Adjustments > Desaturate. This will automatically discard the color information and allow tweaks in levels, curves, or via brightness/contrast sliders. Note that many Photoshop gurus will emphatically state that "brightness" and "contrast" should not be used because of their heavy-handed treatment of an image, but I find them useful for refining black and white.

FOR OPTIMAL CONTROL (ADOBE PHOTOSHOP 6.0 OR HIGHER REQUIRED): Open the file and then go to Layer > New Adjustment Layer > Channel Mixer. At this point, click on the green channel at the top of the dialog box. The green channel is used because it is generally the one with the most information. Then click the monochrome box at the lower left. Use the adjustment sliders to emulate the approximate values Photoshop would select if you had chosen "grayscale" or "desaturate" as above; Red=20%, Green=70%, Blue=10%. Most likely, these will not be the perfect settings, so tweak with the sliders, just as if you had added filters in-camera. With a properly calibrated monitor (extremely important), you can achieve an impressive black-and-white digital file in this manner. Now, click on "Add New Layer" (the half black/half white circle icon at the bottom of the layers pallet); select hue/saturation layer; and finally use the hue and saturation sliders to get the best look. You can also use the lightness slider to adjust the strength of the filter applied.

Be careful when you save your file that you do not overwrite the original color file. With all these black-and-white conversion steps, assign a unique file protocol. I find it convenient to use the original file name and then insert "_BW" just before the ".FileExtension." That way, the file resides on the hard drive right next to the original color image, but I know at a glance that it's the black-and-white conversion.

Subject Selection

Of course, even advanced technical skills cannot produce an impressive image if the subject is not suitable for black-and-white photography. Shipwrecks, marine mammals, sharks and silhouettes are all subjects that make compelling black-and-white images. Subjects like a clownfish in its host anemone can of course be rendered black and white, but the strength of the image may be so tied to the color intensity of the fish and anemone that black and white is counterproductive. Previsualization is the key. Learn what can be done with the black-and-white technique of your choice, and then find the subjects that are best expressed with that unique vision.