Introduction to Infrared Photography

Infrared, or “IR” photography, offers photographers of all abilities and budgets the opportunity to explore a new world – the world of the unseen. Why “unseen”? Because our eyes literally cannot see IR light, as it lies just beyond what is classified as the “visible” spectrum – that which human eyesight can detect. When we take photographs using infrared-equipped film or cameras, we are exposed to the world that can often look very different from that we are accustomed to seeing. Colors, textures, leaves and plants, human skin, and all other manner of objects can reflect IR light in unique and interesting ways, ones that cannot be mimicked with tools such as Photoshop (yes – there are limits to what Photoshop can do!).

Like any form of photography or art, however, it is a matter of taste. I would strongly urge people to explore the world of IR. As the number of cameras-equipped devices proliferates and the associated technologies improve, IR photography may offer the opportunity for photographers to expand into new arenas and differentiate their offerings from those of others.

Terminology

For purposes of this article, I will refer to the infrared light spectrum as “near-infrared”, or simply, “IR”. Near-infrared refers to the spectrum of light just beyond the range humans can detect with their eyesight. This light range is between 700 – 1200 nm (nanometers). Another aspect of the IR spectrum, above near IR, is associated with thermal imaging. Thermal technology was popularized by movies such as, “Patriot Games” and other thrillers, whereby intelligence agencies or military personnel were able to detect villains by measuring their body heat under nighttime conditions. Today’s common digital camera sensors are not able to detect thermal images. Under the right circumstances however, digital cameras can do an excellent job of recording IR.

History Of Infrared Photography

The first forays into IR photography, using special film plates, began in the early part of the 20th century. During WWI, IR photography proved extremely valuable, as images using the IR spectrum were not affected as much by atmospheric haze as normal photos. IR images were also able to show stark distinctions between vegetation and buildings, better identifying potential enemy targets such as camouflaged munitions factories and other key sites. Rivers, streams, lakes, and other waterways were depicted in a very dark hue, making them much more obvious.

During the 1930s and 1940s, filmmakers introduced a variety of infrared-sensitive films that attracted both amateur photographers and Hollywood filmmakers. The military extended its use of IR photography as well, as it sought every possible advantage during WWII. During the 1960s, IR photography saw a number of converts, as some of the leading musicians of the day, such as the Grateful Dead and Jimmy Hendrix, popularized its use via their psychedelic album covers. With the advent of the digital camera in the late 1990s, both regular and IR photography were about to change substantially. In addition to professional and amateur photographers, law enforcement officials rely on IR photography to detect forensic evidence not discerned through normal eyesight.

IR Light Qualities

Reflected IR light produces a fascinating array of surreal effects. Vegetation appears white or near white. Skin takes on a very milky, smooth texture, although veins close to the skin surface can be accentuated and take on a rather ghoulish appearance. Eyes can appear a bit ghostly with the irises registering very dark tones and the whites of the eye taking on a grayish hue. Black clothing can appear gray or white depending on the fabric. IR light can pass through sunglasses that, to the eye, appear extremely dark or mirror-like (see image below). Blue skies take on a much more dramatic appearance as well.

The other aspect of IR photos is a bit tougher to describe and classify. I have found that there is a certain type of contrast, or what I refer to as “crispness”, rarely seen in normal photography. High contrast B&W images are the closest in nature to IR photography, but even those don’t seem to have the same look and feel as IR images. These effects and others are what provide the magic of IR photography – just about everything looks very different from what you are used to seeing within the visible light spectrum.

IR light passing through sunglasses and skin smoothing effect

IR Photography Options

35mm IR film is still readily available for as little as $11 for a roll of 36 prints. It is easy enough to use in your existing SLR, thus enabling you to experiment with IR photography, without committing to anything more than a roll or two of film, and some development costs. Depending on your lab’s capabilities, however, you may find that you have to ship the IR film to another lab that has the ability to process it, much as is required for high-end B&W film.

Another alternative requires buying a circular IR filter (similar to a UV or circular polarizing filter) that attaches to the front of your camera lens. The IR filter prevents visible light from passing through while only allowing IR light to strike your camera’s sensor. These filters will vary in price depending on the size of the filter and the specific portion of the IR spectrum they address. The main difference between the filters is how colors are rendered (more on this in a bit), but this is primarily a matter of taste. Spending more money on a filter that focuses on a different part of the IR spectrum doesn’t necessarily guarantee that you will like the results more than an IR filter costing much less.

What are the downsides of using an IR filter that attaches to your lens? The primary issue is motion blur. Since your DSLR has an IR blocking filter in front of it, very little, if any, IR light reaches it. The IR filter allows only IR light to reach your sensor while filtering out the visible light. The combination of the IR blocking filter and the IR filter on the front of your lens requires very long exposure times. Since the IR filter is very dark, you also have to focus before attaching the IR filter to your lens.

The specific exposure time will vary based on the specific IR filter used, sensitivity of the camera sensor to IR, the specifics of the DSLR’s blocking filter, and of course, the amount of IR light. When I first experimented with IR photography using my Pentax K10D in 2007, I found that I needed to leave my shutter open for 45-60 seconds on a sunny summer day to get a properly exposed IR photo. That might be fine if you are taking photos of buildings or other inanimate objects, but doesn’t work so well with anything that moves, such as people, animals, leaves, flowers, etc. But if you want to get into IR photography quickly with minimal investment, you could buy an IR filter such as the Hoya R72 for as little as $64 (depending on the filter size required) and determine if it is for you. The R72 is probably the most popular IR filter, since it addresses a broad spectrum of the IR range, is economical, and produces excellent IR images.

The last option is to have a DSLR converted for exclusive IR use. This is more costly, but it produces the best results and offers the most flexibility.

DSLRs Converted For Dedicated IR Photography

This option requires the IR blocking filter that sits in front of your DSLR’s sensor to be removed, and substituted with one that allows only IR light to be passed through. It is the equivalent of taking the external IR filter I previously described and substituting it for the IR blocking filter. What are the benefits of this approach? You can use your DSLR just as you do today, relying on normal exposure values and shutter speeds. Looking over my IR photo metadata, I have found that on a typical sunny day from May through August, at f/8 and ISO 100, I achieved shutter speeds of at least 1/125 and often much higher. No long exposures, no time focusing and then needing to shift your focus mode from AF to manual, no fiddling with IR filters on the front of your lens. Most importantly – no blurred images.

The cons of using a dedicated IR camera are cost, the inability to use the converted camera for anything other than IR photography, and voiding your DSLR’s warranty (gulp!). You have two options relative to converting a DSLR for IR use:

  1. Send it to a reputable IR conversion company
  2. Do it yourself

I would strongly recommend option 1 unless you are comfortable with the following: watching an instructional video, being very comfortable with very small, sensitive electrical components (heavy-duty consumers of caffeine can stop here!), disassembling your camera to reach the sensor in an ultra-clean environment, removing the IR blocking filter, replacing it with the IR filter obtained from the conversion company, putting your camera back together, and dealing with any trivial issues such as… dust, hairs, and other particles getting in your camera, as well as any operational issues encountered by some aspect of the disassembly/assembly process. While I have seen the instructional video, and corresponded with a number of people that have performed this operation, I would simply say that it is not for the faint of heart!

There are a variety of companies that specialize in infrared conversion services. One of the most well-known is Lifepixel. I used Lifepixel on two occasions and have nothing but praise for the professionalism of their staff and the quality of their work. Lifepixel first converted my Nikon D40X. Two years later, I sent them my D90. I have to admit that I felt quite a bit of trepidation when I first shipped my Nikon D40X to Lifepixel. The D40X was brand new and I didn’t even take a single picture with it before sending it off in a well-padded box. Something did not feel right about sending a brand new camera to someone other than Nikon to disassemble, modify, and in the process, voiding my warranty!

Before doing so, however, I spoke extensively with Daniel, one of Lifepixels client support representatives. I emailed him with an exhaustive list of questions and concerns. Daniel was extremely patient and thoroughly addressed every issue I raised. Other Lifepixel representatives were just as responsive and helpful. And in nearly 4 years of shooting IR, I can’t point to a single problem with either of the IR-converted DSLRs. One word of caution – whichever company you select for your IR conversion, make sure that you investigate them thoroughly and feel confident in having them modify your DSLR.

Capturing IR Images

Since the DSLR has been modified for IR only purposes, you can use it just as you did when photographing images within the visible light spectrum. ISO, shutter speed and aperture combinations will work in conjunction with one another just as they do with any non-IR DSLR. Matrix metering is always a safe bet with IR, although you may want to experiment with your camera, lens, and lighting conditions to determine if center-weighted metering provides better results in a given situation.

My D40x required me to adjust the exposure compensation button at times, dialing up/down by as much as 1.7. Normally, the range of adjustment was smaller – +/- .3 – .7. Although I have the same IR filter on my D90 however, I have noticed that the D90 requires much less adjustment of the exposure compensation. This was likely a result of the D90 and D40X using different camera sensors. It takes a bit of trial and error to understand what a “good” RAW image looks like in your LCD. With time, however, you will come to recognize when you have properly exposed an IR image and if you need to adjust the exposure compensation.

What About Lenses?

We are trained to believe that the best lenses will produce the best results. However, in the world of IR, the lens that works best in the visible spectrum can be a complete dud in the world of IR. Conversely, lower-cost lenses may perform much better than their counterparts. The main flaws with poor IR performing lenses are twofold; producing a hotspot in the center of the image (slightly different exposure and colors than the rest of the image), and being more susceptible to flare. You may minimize the appearance of the hotspot in post-processing, but it can take quite a bit of work.

And just as with flares associated with the visible light spectrum, IR flares cannot easily be fixed without extensive Photoshop work. Worse, IR flares are harder to detect. When photographing in the visible light spectrum, you can often tell when you are on the verge of introducing a flare based on the angle of the lens relative to the sun. With IR however, you don’t always receive the same visible cue, since you can’t see IR light. Thus it is important to check your LCD as you shoot IR to ensure that you are not introducing flares into your photos since you cannot trust your eyes.

The best strategy is to use lenses that are known to work well for IR photography. Such knowledge isn’t easy to come across. While you can always find a myriad of quality lens reviews, few, if any, address the issue of IR performance. One such source is Bjorn Rorslett’s site. Roreslett is one of the few that specifically tests lenses for IR use. As you can see from his site, the humble Nikon 18-55mm is an excellent performer compared to some other lenses costing a healthy multiple of its price. Over the years, I have come to rely heavily on my Nikon 16-85mm VR. It rarely comes off my infrared D90, since it provides excellent IR performance, is extremely sharp, and has a very useful zoom range that covers just about anything I would wish to capture. And since I have a variety of lenses and experimented with their IR performance, I can vouch for many of Roreslett’s IR recommendations.

Processing IR Images

RAW files afford the most flexibility for post-processing IR images, just as they do for photos taken with visible light. The RAW images viewed straight from the camera are not very impressive – dull, pinkish in color, lacking in contrast. RAW images from an infrared DSLR would likely not persuade many people to delve much deeper into this style of photography. The IR image below (Pennsylvania Memorial in Gettysburg, PA) possesses a decent contrast level, but others can appear blander or “muddied”.

What gives it this pinkish tone? A number of factors influence the look of the RAW IR image – the specific DSLR sensor used, the IR filter installed on the DSLR by the IR conversion company, and software algorithms used for white balance top the list. IR images actually have no color to them, but your DSLR’s sensor has to assign something to the red, green, and blue sensors associated with the Bayer pattern. While each camera’s IR images will appear slightly different than those of others, most modern DSLRs will produce a RAW file that looks somewhat similar to the image above.

I process my IR images in Adobe Photoshop Lightroom, using a preset that serves as a good starting point for adjusting the white balance, tone, contrast, sharpening, etc. The most important of these settings is the white balance, which I set to a temperature of 2100 and a tint of -72. The resultant image looks like the one below. Now the image is shaping up and looks much better than the sea of pink from the original RAW file. Warning: Changing the white balance settings of IR images can result in some drastic psychedelic experiences!

I then import the image above into Adobe Photoshop CS5, where I have created a few actions that swap the red and blue channels to varying degrees. I am partial to a series of actions that result in a mixture of blue and yellow colors. How did I arrive at these settings? Pure experimentation… When I find a particular look that I like, I quickly create a Photoshop action while I have all the settings in plain view and can recall the associated steps. Sometimes I will reduce the color saturation depending on what I am attempting to achieve and/or the nature of the image in question. Other times, I will change the hue of a given color. Again, since IR does not contain any real colors, those that you see are the result of a myriad of factors that will vary from camera to camera. Thus my Lightroom presets and Photoshop actions might produce somewhat different results if applied to photos taken with your specific IR converted camera make and model.

Below is the final version, after some additional processing, noise reduction, and sharpening:

Summary

IR photography opens up exciting new worlds for photographers to explore, particularly considering the flexibility that IR converted DSLRs provide. This article is merely an introduction to the various issues and considerations associated with IR. If you would like to understand more about this subject, drop me a note below, and I will be sure to cover additional aspects of IR photography in future articles.

Update:
Since I wrote this article and others related to infrared photography, many people have emailed me with questions related to IR and advice regarding IR conversion services. Over the last few years, I have recommended Kolari Vision. Kolari Vision has converted four DSLRs for me. I have been very impressed with the quality of the service, turnaround time, value, and performance of the IR converted DSLRs. Ilija Melentijevic, Kolari Vision’s founder, has been especially patient and helpful in explaining the technical and nuanced aspects of converting and using digital cameras for infrared photography. Kolari Vision offers a full range of infrared, ultraviolet, and other specialized digital camera solutions and related filters.