What's Infrared Light, and Why Do Plants Seem To Glow With It?
Technically, the part of the spectrum that most digital cameras can see is called near infrared. It is composed of the frequencies just below visible red light, starting at a wavelength of around 700nm. 

Can My Camera Do This? Most CCDs are sensitive to more than the visible light spectrum. This can cause problems with color balance, so  manufactures often place a "hot mirror" in front of the CCD to block excessive infrared light. There is a simple way to tell if your digital camera is going to see IR. Just take a TV or VCR infrared remote control and point it directly at your camera. Push a button on it and look on the LCD for a spot of light. You should be able to see the infrared beam from the remote as 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, Wratten #88A, Wratten #87, and Wratten #87C filters. I have had great results with an inexpensive 88A filter from Harrison and Harrison (1835 Thunderbolt Drive Unit E, Porterville, CA 93257-9300 phone 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 fisheye. I just cut a small circle 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 cameras LCD. This presents a problem since LCD screens are very hard to see in bright outdoor light. One solution is to use a LCD 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 camera with an electronic viewfinder, like the Canon Pro90 IS or the Sony DSC-F707 Cyber-shot.

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 cameras sensitivity, exposures can be fairly long, even in direct sun. The Nikon Coolpix 990 may need up to an 8 second exposure. I usually shoot at around 1/15 of a second with the more sensitive Coolpix 950, and 1/8 of a second 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's "Best Shot Selector" or the Canon Pro 90 IS's internal Image Stabilizer really help with long exposures. Each is so effective that I find 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 later in a program like Photoshop or 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 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 amount of moisture 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, and 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; others may have a cyan sheen. Rarely will they have a full tonal range. 

Using a program like Photoshop will allow you to clean up the image, adjusting curves and levels. I like to convert my RGB images into true grayscale before I print them. Sometimes I'll simply desaturate the image, other times I find there is less noise in the image if I converted to LAB mode first, choose the lightness channel, and then convert to grayscale. 

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
Inkjet printers can do a marvelous job of creating black and white prints. I've been blown away 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 sparking highlights. With a simple color adjustment I can print sepia tones, or neutral toned prints. 

For anyone who has experimented 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.

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