Apogee Photo Magazine

Unseen Infrared 

by Sandy Sorlien

Understanding and Controlling Black & White Infrared Film

For more than fifteen years, I used nothing but black-and-white infrared film for all my personal work. Before coming to photography, I’d been a printmaker working primarily with etching, so when I was introduced to Kodak High-Speed Infrared in 1980, I quickly took to its grainy, aquatint-like texture and softened details. I saw its potential for translating my vision of the landscape and freeing me from the confinement of the fume-filled etching studio. However, seeing its potential was one thing; controlling it was quite another.

There’s a lot of bad infrared work out there, and because it’s easily recognizable as infrared, a stigma is slapped on serious infrared artists--even those creating good results. Ironically, far more bad photography is being done with T-Max 400 (to pick a popular film), but it doesn’t have its own distinctive look, so it doesn’t suffer a bum rap. To complicate matters, there are particular problems with infrared that must be overcome. I see the main problems as follows:

• 1. Many infrared users don’t understand the way filters affect light, particularly infrared light.

• 2. Certain atmospheric conditions will almost guarantee a fuzzy, undifferentiated image.

• 3. Photographers are seduced by the otherworldly look of their IR images, regardless of whether that look is appropriate for what they’re trying to say.
  

Tackling Point #1 

It’s important to realize that successful infrared photography is a blending of two different kinds of light (unless you’re using the "true infrared filter," which I’ll get to later). There are several infrared and quasi-infrared films available from three manufacturers, and they're all sensitive to both infrared light waves, which we cannot see, and visible light, which we can. Ilford’s SFX and Konica’s Infrared films (35mm & 120) are barely infrared-sensitive; they’re mostly just red-sensitive. Kodak’s HIE (High-Speed Infrared, 35mm and 4x5) is the only true black and white infrared film commercially available. (Kodak also makes an Ektachrome color infrared transparency film, recently revamped to accept E-6 processing. I haven’t used it much so I won’t offer advice on it here.)

Both visible and infrared light waves are radiated from light sources such as the sun (and the sky as a vast reflector), artificial lights of all kinds, and electronic flash, and are reflected from all objects, albeit with varying intensity. For instance, living foliage reflects a tremendous amount of infrared radiation. That’s why sunlit grass and trees in a black-and-white infrared print appear to glow with whiteness. The infrared produces additional exposure on those parts of the negative.

Infrared light waves are longer than visible light waves. The distance between waves is measured in nanometers (millionths of millimeters!). Picture the visible spectrum lined up from left to right: violet, indigo, blue, green, yellow, orange, and red. The light waves become longer as you move to the right, from about 400nm at violet to 700nm at the end of the visible spectrum where red is. After red, you're in the invisible infrared ("below red") region. (Conversely, ultraviolet wavelengths are "beyond violet" to the left, shorter and also invisible to our eyes.) Ilford and Konica’s "infrared" films are sensitive to 740nm, but Kodak films go almost to 900nm; hence its effects are more pronounced.

The key to controlling the mix of visible and infrared light lies in the use of filters placed on the camera lens at the time of exposure. The long IR wavelengths will all pass through colored filters at the red end of the spectrum--including yellow, orange, red, and the astounding 87 and 89 series filters, which are such a dense red that practically no visible light gets through. (To us, they appear black and opaque.) Yet all the infrared gets through. These "true infrared filters" are the ones to use when you want the maximum effect of infrared radiation – drastically whitened foliage, maximum grain, altered tonalities, and extremely softened edges. The redder the filter, the darker a blue sky will print. (This is also true for any black-and-white panchromatic film. Red passes red and blocks its opposite, blue, diminishing the exposure on the negative where the blue would be.)

Most books and articles on infrared advise using a medium #25 red filter for artistic applications. It lets in some visible light, so there’s a reasonable mix, and you can see through it well enough to compose and focus. I agree. Start with this filter, but sometimes you may want to tone down the infrared effect, using lighter orange or even yellow filters to let in proportionately more visible light. As I used this film over the years, I went from red to orange to yellow. Everything I've shot since about 1991 was through a yellow filter.

Tackling Point #2:

Be aware that IR waves, like visible waves, are affected by moisture. You may think that infrared film reads heat, but no. Extremely sensitive infrared materials used in scientific applications will record heat, but even Kodak’s film is far less sensitive than that. We can put our hot little hands on it without fogging it (thank God!). Here’s a phrase you’ve heard before: "It’s not the heat; it’s the humidity." In this case, the old phrase is true. The scattering of infrared by droplets in the air spreads exposure all over the place. (Stop it before it kills your picture!) If you shoot on a humid day, you’re likely to end up with those fuzzy, undifferentiated scenes that critics of infrared know so well.

For successful exposures, knowing when and where infrared appears is more useful than the bogus information given by your exposure meter, which can't read infrared. You can use your meter to gauge the visible light, of course, but the readings can be misleading if you’re using a dense filter or if your subject reflects a lot of IR wavelengths. I have never used my meter for outdoor infrared work.

Herewith, a few recommendations for Kodak film:
Sunny, dry day, subject in sun: 1/125, f/11 (stop down to f/16 for beach or snow scenes in sun, or areas with a lot of foliage). Cloudy day, subject under open sky, 1/125 f/8. Shady area or clouds late in day, 1/60, f/5.6. (You’d be surprised at the infrared exposure coming out of the shadows.)

I did use my meter for studio work, where my lights gave off relatively little infrared. Kodak’s advice for ISO settings is a stop off, I think. They suggest ISO 50, presumably for readings made before adding any filters. I’d suggest ISO 100 before adding the medium red filter, or 200 with through-the-lens-and-filter metering. Ignore regular filter factors, because remember, infrared exposure pours right through.

Electronic flash also emits infrared radiation. Here’s something fun to do with flash: cover your strobe with a piece of Wratten gelatin filter #87, the opaque red. (No need for a filter on the lens in this case.) You can now take flash pictures in dark places like bars or movie theatres, and no one will see the light coming out. Yet all the infrared in the strobe passes through the filter, reflects off the subject, and exposes your infrared film!

If you use the flash without any filter over the flash source, try ISO 100 for your automatic modes, assuming the medium red filter is on the camera lens. Be aware that you need to load and unload your camera in the dark (Kodak HIE only). I carry a small changing bag at all times. Those extra-long wavelengths are able to penetrate the fuzzy black lip on the 35mm canister. They also sneak through some plastics, so test your film holders if you use the 4x5 film and turn the lights down a bit when processing in a plastic tank. After that, processing is easy; just develop in D-76 for 11 minutes.

Keep in mind that the longer wavelengths focus at a different point than the visible waves (contributing to the characteristic softness of your image). Some lenses have a red IR focusing dot, so you can make a small adjustment for that difference. But remember, you have to focus the visible light, too, unless you’re using an opaque filter. So, I wouldn’t bother making the adjustment unless you’re doing close-up work with a large aperture. Stick to f/8 or smaller, and you’ll be fine just focusing the visible light as usual.

Tackling Point #3:

When all is said and done, and you’ve tried all the films and filters and photographed everything from babies to battleships in infrared, examine what you’re trying to say in your personal or commercial work and decide if this film is working for you or against you. As your mother probably told you several times during your errant teen years, "Just because it’s cool, doesn’t mean it’s right." (Hey, I didn’t listen to mine, either, but if you’re trying to tell a straightforward story or render meticulous detail, infrared is the wrong medium.) But infrared can be very useful for suggesting a dream state or a fictional narrative or landscape, or for rendering objects in a painterly way. A controlled and gentle handling of IR may elicit a lushly romantic, wistful, nostalgic, or elegiac tone. Bolder infrared work may convey a strong sense of the otherworldly or macabre. After all, we’re photographing a kind of light we can’t normally see. There has to be some mystery in that.
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Sandy Sorlien teaches photography at The University of the Arts in Philadelphia and has exhibited and published her photographs and writing nationally. She received Fellowships in Photography from the Pennsylvania Council on the Arts in 1990 and 1999. Her book of black and white infrared images entitled “Fifty Houses: Portraits of American Architecture” is due out in Fall 2001. Sandy is offering a workshop in Infrared Photography at Peters Valley Craft Center in August, 2000.

All photos are Copyright © Sandy Sorlien. They have been digitally watermarked and may be used for your on-line viewing pleasure only. No other uses are allowed without expressed written permission from Sandy Sorlien.