Near infrared photography is a niche photographic specialty that may achieve striking results in situations where conventional photography is bland. Infrared images are familiar to many photographers for their high contrast, dark skies and water, and glowing foliage. In addition, IR images have a strong ability to cut through haze in landscape photography, reduce blemishes in portrait photography, and expose whether coloration is natural or artificial in forensic photography.
Infrared film and digital images record light from the visible as well as the near infrared portions of the EM spectrum. It should not be confused with far infrared or “heat vision” that are used in scientific, firefighting, and police fields more than art. I have been shooting infrared for about eight years. My first experiments were with Kodak High Speed Infrared (aka HIE…no, I don’t know why it’s known as HIE rather than HIR. E for emulsion?) 35mm film shot on my old Minolta Maxxum 5000. HIE was expensive and had to be loaded and processed in total darkness.
Among infrared films of the era, HIE was particularly sensitive to the near infrared- some other films were more oriented towards the visual spectrum with only limited infrared sensitivity. Since HIE, like other IR films was still sensitive to visible light, subjects were best shot using a red filter in order to get the strongest infrared effects. HIE produced photos with a lot of grain. HIE lacked the anti-halation backing found on most films, resulting in strong highlights appearing to glow. Since infrared light focuses on a different plane than the visual spectrum, the focusing had to be adjusted using the infrared guide marks on the lens. Unfortunately, HIE was discontinued in 2007; like many films, it fell victim to declining demand in an increasingly digital era.
Digital camera sensors are sensitive to infrared. Since this sensitivity can result in unusual color images, cameras are almost always equipped with an infrared “cut-off filter” that removes most IR light. Since some limited sensitivity remains, some photographers place an infrared filter on their cameras to take IR shots. This is an imperfect solution. Since the cut-off filter removes most IR light, very long exposures (as much as 30 seconds) are necessary and tripod use mandatory. The filter is also opaque to visible light, so when using an optical viewfinder the picture must be composed and focused before attaching the filter.
A better, if expensive, solution is to purchase a modified camera. I took the plunge in 2007 with a Canon XTi modified by LDP LLC. The company removed the infrared cut-off filter and installed an internal IR filter that is opaque to visible light. This eliminates the disadvantages of the external IR filter- images can be composed in the optical viewfinder and very high shutter speeds are possible. Indeed, on a sunny day my most common shooting settings are 1/500 second at f8, ISO-100. The focusing on the modified camera works perfectly without needing to compensate with the infrared guide marks on the lens. The light meter is not accurate for IR, so I always shoot in manual mode, adjusting the settings with the help of the histogram. Since it’s an older camera, I have to do this after a test shot since it predates when SLRs came equipped with live view. Digital IR doesn’t have the grain or halation aspects of classic Kodak HIE, although those are easily mimicked if desired with the “Diffuse glow” filter in Photoshop. I typically process my infrared images in RAW and find that most images require Levels to look their best. Many also need dust spots removed- the sensor-cleaning mechanism was removed along with the infrared cut-off filter.
Infrared is my medium of choice for aerial landscape photography. It has been my observation that when flying commercial aviation, aircraft quickly ascend to an altitude in which there is heavy haze obstructing the landscape below. Haze is strongest in the blue portion of the visible spectrum, which doesn’t affect IR images as strongly. This is one aspect of infrared that cannot readily be simulated in Photoshop- you may be able to fake dark skies and bright foliage with a black and white conversion, but even tweaking the Levels will not give you nearly the same level of detail as infrared photos under hazy conditions.
Mountains are particularly striking. Contrast can be very high between sunlit snowy areas and dark shaded areas, as only areas in direct sunlight reflect infrared Under some circumstances viewing an IR image can be jarring in that we expect subjects further away (like a distant mountain range) to be hazier than closer subjects.
Infrared portraits have mixed blessings. Skin blemishes and wrinkles are substantially reduced without the slightest “airbrushing” in Photoshop. The subject’s eyes however may appear unnaturally dark, especially if they have blue eyes. Clothing also tends to look lighter. Cotton, after all, starts off light and dyes are designed to alter a garment’s appearance in the visible spectrum, not infrared. Sometimes this effect adds to the “luminous” quality of the portrait and sometimes it just looks strange. Sunglasses are often transparent to infrared- again, they’re designed to filter out visible and ultraviolet light, not infrared. Sometimes it’s nice to be able to see your subject’s eyes under the glasses, and sometimes it just looks odd. A more detailed article on IR portraiture can be found at Tracy’s Creative Imaging.
One more thing I hesitate to mention. A number of years ago there was a controversy in which some creeps were reported to be using infrared night mode on video cameras in order to see through skintight clothing. It is true that some materials may be more transparent to infrared, but this is a rare phenomenon. I was actually dubious about the alleged “x-ray vision” aspect of IR until I compared a pair of photos taken in Paris at the same time. In the color photo, a woman sitting outside the Louvre in the background of a photo has an opaque shirt. In the IR photo of the same scene, the shirt is by no means transparent but the woman’s bra was visible. Europeans and their impractical clothing!
In a typical trip, I tend to take about ten to twenty color photographs for every infrared shot. I will be the first to admit that infrared has limited uses. Contrary to popular belief, infrared photography is not particularly useful at night. I suspect part of that perception is due to confusion between near infrared and far infrared photography. Far infrared, as demonstrated by FLIR footage seen from police helicopters or thermal imaging cameras (TICs) used by firefighters is extremely useful in pitch darkness. Near infrared, on the other hand, is only useful at night if infrared light is being actively projected, as found in some night vision devices as early as World War II. Infrared is really only effective in bright sunlight- on cloudy days, IR images are bland with little contrast.
Like other black and white images, infrared images are most effective in subjects in which form and detail are more important than color. Infrared takes the advantages of black and white a few steps further, producing especially strong images when foliage is sunlit, haze is obstructing color images, skies are too bright when the subject is properly exposed, and when a sunlit primary subject is well framed by areas that aren’t sunlit. Used properly, a near infrared camera can produce truly crowd-pleasing images.