Infrared Camera Conversions

Infrared radiation (IR) is electromagnetic radiation with a wavelength that is longer and a frequency that is shorter than that which produces visible light. Although capturing imagery using IR has forensic and scientific applications, there are currently no production IR cameras available.

The alternatives are to use a filter, to retrofit a digital camera or to simulate IR in postprocessing, as explained on page 280–281.

An IR filter appears either black or very dark red, letting IR pass through it while blocking visible light. One problem with this kind of filter is that since it blocks visible light it can be very hard to see and compose through if you are using a digital camera. For superior results, I’d recommend converting an existing camera. An older model digital camera so long as it has a manual exposure mode and is capable of RAW captures is probably sufficient for IR retrofitting.

Most digital sensors, particularly older ones, have considerable inherent sensitivity to IR (as well as UV, the radiation at the opposite end of the visible spectrum). Retrofitting in part involves removing any filters that block IR. This may change the distance from the back of a lens to the sensor, and therefore its focusing. So it’s a good idea to have the lens you will use with your IR camera calibrated for the retrofitted camera at the same time it is modified.

There’s nothing inherently monochromatic about an IR capture, although IR captures will typically not exhibit a great dynamic or color range. RAW captures often have a kind of pinkish hue at default settings.

Personally, I prefer to present my IR captures in black and white, with the expectation that I’ll be converting not-very-colorful RAW captures to monochrome using the techniques shown in this book.

If you don’t want to go to the trouble of converting your infrared images to monochrome each time, it is possible to get your camera equipped with a black and white IR filter at the time it is retrofitted. However, I feel that this limits rather than expands your options.

What does an IR capture look like? This can be hard to know until you experiment in a given situation—one of the great things about digital IR capture is that you get immediate feedback on the LCD screen.

Foliage appears white rather than green. The more plants are growing, the whiter they appear. Skies are dark, although clouds can be quite dramatic. Depending on the lighting you use, portraits can be very unusual with pale, milky skin and dark, dark eyes.

Infrared and monochrome go very well together. If you’ve never tried to make a photo using a light spectrum not visible to the naked eye, this may be just the time for you to experiment with one of the most creative effects available to black and white photography.

A RAW infrared image in color is shown next to the in-camera almost monochromatic JPEG version in Adobe Bridge (see page 276 for the final version of this photo following black and white conversion).

Here is the infrared image shown with default “As Shot” settings in ACR. The white balance of this image is 2000 degrees Kelvin, the lowest possible temperature on the ACR scale.

Camilla—Infrared macro captures of flowers can produce surprisingly nuanced imagery, with areas that appear to be sharp and in focus contrasting to soft areas. Whatever the original color of the flower—this Camellia was vibrant red—it is likely to appear mostly white, or very light, in the infrared capture.

Nikon D70 converted for IR capture, 50mm macro, 6 seconds at f/32 and ISO 200, tripod mounted; processed using Photoshop.

Living Forest—Lush, growing foliage shows up as brightly white in an infrared capture, like the lichen and background forest in this shot.

Nikon D70 converted for IR capture, 65mm, 1/13 of a second at f/9 and ISO 200, tripod mounted; processed using Photoshop.

Drydock—This is a photograph made in the abandoned naval shipyard at Mare Island, California. During World War II, more than 40,000 workers built the battleships here that waged the war in the Pacific theater. An infrared capture helped me convey the eeriness and desolation of the scene.

Nikon D70 converted for IR capture, 18mm, 1/160 of a second at f/6.3 and ISO 200, hand held; processed in Photoshop.