Infrared Examined
Technically, the part of the spectrum that most digital cameras can see is called near infrared. It is composed of the frequencies that are longer than visible red light, starting at a wavelength of around 700nm (nanometers). These longer wavelengths often are absorbed or reflected quite differently than visible light. Most noticeable is the way that the internal structure of leaves strongly refract near IR. The resulting brightness is dependent on the type of leaf and its health. Other things, such as still water or a deep blue sky will absorb IR, and thus appear very dark.

Can My Digital Camera Do This?
Most CCDs are sensitive to more than the visible light spectrum. Manufactures often compensate for this by including a "hot mirror" to block infrared light, and thus maintain a true color balance. The simple way to tell if your camera is going to see IR is to take a TV or VCR infrared remote control and point it at your camera. Push a button and look on the LCD for a spot of light. You should be able to see a point of light. If you do, you will be able to shoot IR images with your camera.

Next, you will need to buy a filter that will block all visible light but allow infrared radiation to pass. Different filters block varying amounts of shorter wavelength light. In increasing degree of strength are the Wratten #89B, #88A, #87, and #87C filters. I have had great results with an inexpensive 88A filter from Harrison and Harrison (1835 Thunderbolt Dr., Unit E, Porterville, CA 93257; (559) 782-0121).

If your camera has no thread for a screw-in filter, you can buy gelatin filters and cut them down to fit over your lens and tape them in place. I find gelatin filters especially helpful for supplemental lenses like Nikon's CoolPix fisheye. I just cut a small circle about the size of the rear element of the lens and place it between the camera and fisheye before I screw it in place.

Shooting Technique
When you place a sharp cut IR filter in front of your digital camera's lens you are granted entry to an invisible world. Surreal landscapes unfold with unexpected graphic elements, such as inky black skies or open luminous shadow areas.

To compose really strong images in this netherworld requires close examination of your camera's LCD. This presents a problem since LCD screens are very hard to see in bright outdoor light. One solution is to use a screen hood and magnifier like the Xtend-a-View (www.photosolve.com). This clever device fits over your camera's LCD, blocking all extraneous light, and magnifies your screen by a factor of 2x. Or just use a digital camera with an electronic viewfinder, like the Canon Pro90 IS.

When I go looking for infrared images, I'll often walk with one eye to the LCD viewfinder and the other open to see what's around me. I shoot lots of images, as there are no expensive film and processing costs to deal with.

Depending on your camera's sensitivity, exposures can be fairly long, even in direct sun. The Nikon CoolPix 990 may need up to a 15 sec exposure. I usually shoot at around 1/15 sec with the more sensitive CoolPix 950, and 1/8 sec with the Canon Pro90 IS. If your camera allows you to increase the apparent ISO, that will help a bit. Features such as the CoolPix "Best Shot Selector" or the internal Image Stabilizer in the Canon Pro90 IS really help with long exposures. Each is so effective that I rarely need a tripod.

A tripod can be very useful, however, as it will allow you capture intriguing pairs of color and infrared images. Just shoot with the filter, then remove it and take a second shot. The two images will be in perfect register, and will allow you to experiment with mixing colors with your infrared image using a program like Adobe Photoshop or JASC Paint Shop Pro.

Choosing Your Subjects
Plants are quite spectacular in the way they glow. Healthy leaves can go almost white, while dead and dying vegetation is often quite a bit darker. The bark of trees can range from a rich black to a birch like white.

People's skin can glow with a soft light, and occasionally a latticework of small veins can be seen just beneath the surface. Eyes can be quite spooky, as the iris can absorb or transmit infrared in unexpected ways.

Bodies of water can reflect IR if the surface is in motion but will tend to absorb it if it is still. Shallow water is often quite transparent.

The sky will range from a light gray to black, depending on the angle you are shooting relative to the sun and the kind of atmospheric particles causing backscatter. Clouds are often brilliant white, becoming strong visual elements.

Cityscapes can be richly varied, as buildings reflect and absorb different amounts of IR. Overall image clarity is often dramatic, as atmospheric scattering of near IR wavelengths is generally quite low.

Post-Processing The Image
Your infrared images may have some strange color and tonal balance to them right out of the camera. Some may go quite red; have a cyan sheen. Rarely will they have a full tonal range. Adjusting curves and levels in a program like Photoshop will allow you to clean up the image. I like to convert my RGB images into true gray scale before I print them. Sometimes I'll simply desaturate the image. Other times I find there is less noise in the image if converted to Lab mode first. You then choose the lightness channel and convert to gray scale.

Photoshop also provides the means to produce other classic infrared film effects. Kodak High-Speed Infrared film was quite grainy, and had no anti-halation backing. This caused the highlights to flare and glow with a soft, dreamlike effect. You can add both these effects to your digital images using Photoshop's Diffuse Glow filter.

Printing Your Images
Ink jet printers can do a marvelous job of creating black and white prints. I've been pleased with the new Canon S800, a six-color printer that uses individual ink cartridges. My black and white infrared prints have rich, deep blacks, and sparkling highlights. With a simple color adjustment I can choose between printing sepia or neutral toned prints.

For anyone who has any experience with infrared film, shooting digital infrared will seem like a dream come true. Being able to preview the results in real time is critical to composing the most effective images. For wedding photographers thinking of offering IR shots as an added feature, digital allows instant results as well as the ability to shoot color with the simple change of filter.

The Sony DSC-F707 Cyber-shot--The Ultimate IR Camera
Imagine a 5 megapixel digital camera with a simple switch that moves the IR blocking "hot glass" out of the optical path, a camera with an excellent electronic viewfinder, and even a pair of built-in infrared emitters to illuminate your subject in total darkness. Sound like the ultimate IR camera? In low-light conditions, the Sony DSC-F707's IR abilities are phenomenal. Unfortunately, Sony has intentionally limited its ability to work in normal daylight. Stung by sensationalist reports in the media about how its infrared capable video cameras could see through clothing, (some kinds of material, especially wet bathing suits, tend to be somewhat translucent to IR light), Sony has limited the Cyber-shot's exposure range. When in "NightShot" (IR) mode, the camera will not adjust its exposure to be shorter than 1/60 of a sec at f/2.0, thus greatly overexposing in daylight. Combining an #88A infrared filter with neutral density filters can compensate for this limitation, but it's a shame that this artificial restraint exists at all. Overall, this camera is a joy to work with, opening up a whole world of nighttime infrared possibilities.

To see more of our digital infrared work, and a list of IR resources, please check out www.InfraRedDreams.com.

Chris Maher and Larry Berman are photographers, writers, and web designers, specializing in image intensive photography sites. For more information visit their web sites at: www.ArtWebWorks.com and www.BermanGraphics.com.

Manufacturers/Distributors
Adobe Systems Inc.
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Canon U.S.A., Inc.
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JASC, Inc.
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(952) 930-9800
fax: (952) 930-9172
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Nikon Inc.
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