This tutorial probably doesn't apply to you if you are using:

1. A film camera
2. A camera that does not have (at least) long-time exposure settings (e.g. a camera with fully automatic exposure)

I recommend digital cameras with fully manual exposure settings (e.g. both F-stop and exposure time) for this process.

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The Introduction

It's fairly well known that other animals, especially insects, can see things that humans cannot. For instance, bees are inexplicably drawn to certain red flowers while they ignore others entirely. A famous scientific experiment testing the color vision of bees found that the insects could distinguish between two gray cards which, to the scientists, looked identical.

The difference was infrared light. Infrared is the sets of wavelengths that immediately precede red in the electromagnetic spectrum. (Similarly, ultraviolent is the set that comes immediately after purple.) Like visible light and radio waves and x-rays, infrared is just another form of light energy. Unlike visible light, though, we can't see it with the naked eye. Infrared comes in two varieties: near and far. Near infrared is the set of wavelengths closest to the visible color red. Far infrared is what we detect when we use thermal imagers and heat sensors.

All objects reflect infrared light just like visible light, except we cannot see it. When we capture this light, we're measuring "how much" light is reflected (like a black and white visible-light photograph does) and not any semblance of color. Color is the result of our brains interpreting visible light, and is not defined for the infrared wavelengths. We can only measure "brightness" or "intensity".

The Anatomy

Most likely you're reading this because you own an instrument that can detect near IR wavelengths. Your camera's digital sensor, the CCD, is incredibly sensitive to infrared light. In fact, on many cameras, the CCD is more sensitive to infrared light than visible light. The manufacturer places a piece of glass called a hot mirror between the lens and the CCD. A hot mirror is designed to reflect infrared light so that it doesn't screw up the image quality produced by the visible light. But no glass mirror is perfect - every one lets a little bit of light through.

(Note: Digital cameras cannot detect far infrared or "thermal" wavelengths. Sorry.)

The Inequality and The Test

Some hot mirrors are better than others. Some CCDs are more sensitive to IR than others. Your camera may not be capable of taking infrared pictures in the sense I'm about to describe. After all, the manufacturer doesn't intend these cameras to be used for that purpose. Some cameras are notoriously good at taking infrared photographs. It's actually considered a negative aspect if the camera is good at this.

The best way to test this using your camera is the so-called remote control test. Remote controls use infrared light to communicate with your televisions, VCRs, DVD players, and digital video recorders. Take your TV remote and aim it at the end of your camera. Look at the LCD screen preview (not the viewfinder). If you can see a white flash blinking at the tip of the remote control, then your camera is infrared sensitive. On my Canon A75, the infrared signal is so bright it "blooms" out and smears across the LCD screen. My Canon G6 barely registers the light at all. Most newer Nikon cameras have medium sensitivity.

The 2-megapixel Olympus C2020Z and cameras which appeared around the same time period are famous infrared cameras. The Sony CCDs used in those cameras are extraordinarily sensitive to IR. As I said before, my Canon A75 takes great IR photos. I've heard that many Nikon cameras, including the D70, also take great IR photos.

The Filter

Now that you know your camera can view infrared, the trick is to block out enough visible light that it doesn't overwhelm the miniscule amount of IR reaching the CCD. You can pick up an infrared pass filter, which allows only infrared light through, through Ebay or your local camera shop. I recommend the Hoya R72 filter for cameras with high sensitivity and is available in a variety of sizes. It blocks 99% of visible light, allowing only the slightest amount of visible red light into the camera. If your camera isn't as sensitive, you can still get dramatic photos using the Tiffen Red #25 filter. If your camera is extraordinarily sensitive, you can use a Wratten #87 filter, which allows no visible light at all. You'll also need whatever mount your digital camera uses to attach filters.

A good infrared pass filter looks black to the naked eye, since it allows no visible light to pass through. If you're using a DSLR, this means that you'll need to compose your shot without the filter in place, because you won't be able to see through the viewfinder once the filter is attached. If you're using a fairly sensitive non-SLR camera, you'll be able to see the result immediately on the LCD preview. If your camera has low sensitivity, you'll probably need to compose the shot without the filter.

The Step-by-step

1. Find a sunny place. A clear day with a deep blue sky and few clouds is recommended. The sun is an incredibly bright source of infrared light and so your exposure time will be greatly reduced.

2. Mount your camera on a tripod. This is essential because digital infrared photography must use a long-time exposure to compensate for the camera's hot mirror.

3. Compose the scene without the filter in place (or with it if you can see what you're doing on the LCD).

4. If you have manual white balance, take a sample now. If not, set it to automatic.

5. Put the filter on.

6. Set your exposure time to one second with the widest F-stop (lowest number) your camera supports.

7. Set your camera to take a delayed exposure. You don't want to be jiggling the tripod when you're taking a long exposure. I use the 2-second delay setting for most of my IR work.

8. Take a picture of something interesting. I recommend a tree. If the photo turns out too light or too dark, play with the exposure settings until you get it right. While a properly exposed photograph is preferred, you will have better luck with a slightly overexposed photo than a slightly underexposed one.

The Focus

Infrared light focuses differently than visible light, due to its much longer wavelength. Essentially, it doesn't bend around corners as easily and so it needs a stronger lens. The impact on you is minimal, provided your camera has high sensitivity and a good autofocus. A good autofocus, found on most newer cameras, is perfectly capable of focusing in infrared.

The focal length used will seem ridiculously short. For instance, the camera may focus at 4 feet to take a photo of something a mile away. This is important because many cameras cannot focus closer than a certain number of millimeters unless they are in macro mode. If your subject is closer than about 10 feet, you may need to use the camera's macro focus mode.

If your camera's autofocus cannot detect the image or your camera has low sensitivity, you may have to guess. I don't have a focal length conversion chart, although I'm sure somebody has produced one somewhere on the Internet. If you don't have manual focus, you're out of luck.

The Results

If you did everything right, you'll get a very strange photo. Very likely, it will be some shade of purple or yellow, depending on your camera's CCD and hot mirror. This is because the green and blue channels on your camera are picking up most of the infrared light while the red channel is capturing what little red light makes it through the filter. These are false colors. Color is simply not defined for infrared wavelengths.

On my camera, photos are a nice pastel pink and most of the IR information is in the green channel. Other photos I've seen on DeviantArt seem to produce a sort of brown or yellow color. If you are using the Wratten #87 filter, you are probably blocking all of the red data, which might explain the brown photos.

The Channel Mixing

You probably don't want a purple photograph. There are two ways you can deal with this, depending on your camera and the resultant photographs:

1. If your photo is pink or purple, you have red data you need to remove.

Open your picture in Photoshop (or The GIMP). Find the Channel Mixer (in Photoshop, it's under Image > Adjustment > Channel Mixer). Click the "Monochrome" (or equivalent) checkbox and slide the sliders until you are happy with the photograph. I suggest setting the Red channel to a very low value, less than 20%. Now, use your tool's Colorize function (in Photoshop this is found under Hue/Saturation) to add a little tint of blue or yellow to the photo.

2. If your photo is brown, you do not have red data to remove.

Open your picture in Photoshop or The GIMP. Find the Channel Mixer (in Photoshop, it's under Image > Adjustment > Channel Mixer). Do not click the "Monochrome" (or equivalent) checkbox. With the "Red" channel selected, choose 100% for blue and 0% for red and green. This will leave your photo a nice pale blue color. If it's too colorful, desaturate it.

The Auto Contrast

Save a copy of your photograph now.

You probably think that your photo looks great, but it probably does not. IR is notorious for its high-contrast "striking" appearance with deep, sharp shadows. This effect is a result of the difficulty bending these wavelengths of light around corners.

Use Photoshop's Auto Levels tool to increase the contrast of your photograph. If you don't like that result, at least increase it manually by 10-20%.

Since you're accustomed to seeing your photograph with less contrast, it probably will look extremely dark to you. Save the contrasty copy separately and come back in 24 hours, once your brain has forgotten the original image. Look at the first and second versions of the photograph you saved. You'll usually find that the high-contrast copy looks much better.

The Quirks

A few objects you know and love appear distorted or otherwise unusual in infrared. We're measuring how much infrared light is reflected from something, which we cannot see with our eyes. Essentially, manufacters make dyes for humans, not bees, and so don't care how much or how little IR is reflected.

Hair dye is a perfect example of this. In visible light, it can take any color of the rainbow. In infrared, hair dye reflects almost 100% of the light, which means that it appears completely white in the photograph. Your friend with the silky black hair will be a platinum blonde. Most natural hair colors appear as some shade of gray.

Foliage, like leaves and grasses, will almost always turn white. This is one of the most visible parts of IR photography and one of its most famous. It lends the "dream-like" aspect to the photograph. Woody surfaces, like tree trunks, will probably turn dark or black, particularly toward the end of summer.

The sky reflects almost no infrared and so will appear completely black. This is the other "dream-like" effect that is so common in IR photographs. Clouds, on the other hand, totally reflect infrared and so appear very white, for a nice contrast effect against the dark sky. Haze, unfortunately, also reflects infrared wavelengths and is often invisible to the naked eye. If your sky doesn't produce the deep black common in IR photographs, it is probably hazy.

Unpainted metal reflects almost no infrared light, turning black in an IR photograph. Painted metal will reflect depending on the color chemicals in the paint. Anywhere a point of light reflects like a spotlight from the metal (specular highlights) will still appear white, like it does to the naked eye. The infrared highlight will probably be smaller than the visible spot.

Clothing is unpredictable because the dyes used to produce the same visible color often reflect different amounts of infrared light. Always take a photo of a model's clothing prior to a photo shoot. Lacy substances, like lingerie straps, will almost always be black or dark, while most fabrics will become lighter or white. It seems that whatever chemical is used for black dye almost always turns totally white.

The Words of Warning

MOST IMPORTANT: Some clothing is very white because some of the infrared light is passing through it unscathed. In other words, it becomes slightly transparent. Make sure your model's clothing does not do this before you take pictures you'll be showing publicly.

Also, things you photograph should, ideally, be still for the entire length of the photograph. If your camera, subject, or model moves or shakes during the exposure period, it will appear blurry. This means that trees in the wind and moving clouds usually do not make good subjects, although the slight motion blur against an unmoving background can add to the "dreamy" effect.

The long exposure also has an interesting effect on moving water. You may or may not find this desirable in your photo.

The Conclusion

So there you go. Have fun. Leave a comment here if you have any questions.