Blue Pixel

Wednesday, February 28th, 2007 by Reed Hoffmann

Ever since I first read about infrared photography, many decades ago in high school, I've been intrigued by the idea. The images produced by it are otherworldly and I wanted to try my hand at it. Unfortunately, my attempts back then always ended in failure, not in small part due to the difficulty of using and processing infrared film. Thankfully, times have changed, and digital's taken film out of the equation.

In the past few years a couple of friends of mine have been playing with digital infrared. They were doing it using cameras that were known to be fairly sensitive to infrared (such as the Nikon Coolpix 5400) and then using very dark (nearly opaque) filters on those cameras. The resulting photos were close to what infrared film would give. However the darkness of the filter meant high ISO’s, multi-second exposures, having to work on a tripod and difficulty focusing. Still too much hassle.

Then I started hearing about companies that would convert a digital camera to infrared-only. The process involved taking the camera apart, removing the low-pass filter over the sensor and replacing it with a filter that passed light in the infrared spectrum. The result was a camera that could only be used for infrared, but could be shot with normal exposures and easily focused. That sounded like a system I could work with. Leading a photo trip to Sweden last summer, I met one of the attendees who’d had that done to a compact camera, saw the photos it was capable of, and I was sold.

Heading to eBay I bought a used Nikon D70, which would let me use the large collection of Nikon lenses I own. Next I shipped it off to LifePixel (http://www.lifepixel.com), the company the student had used. There are several companies that do this, and the price generally ranges from $200 to $500, depending on the camera. Once in hand, it was time to try it out.

Smart people no doubt would do some research on the peculiarities of shooting infrared, but I’m more of a “shoot first, ask questions later” type. Having done it that way, I can say that a little knowledge will help a lot! First off, you have to know that you need light to take photos. Now that may elicit a “Duh!” from a lot of you, but infrared works best in bright sunlight. The most dramatic results come from objects that reflect that sunlight. They record as white. The sky, which isn’t reflecting light, tends to go dark gray to black. Colors react differently, unless you choose to set the camera for monochrome, which I wouldn’t recommend.

The camera is still an RGB capture device, and as such records three channels of information, even when shooting IR. If you shoot in Auto white balance, or any of the default settings (like Daylight or Fluorescent), you’ll get an image with strange color. Some people like the color, some don’t. If you shoot a Preset (or Custom) white balance off of green grass, then everything green (such as grass and leaves) will be rendered neutral or some shade of gray. That’s the look you’re used to seeing with infrared.

Even if you’ve done a preset, you’ll still sometimes have color in the image. Overexposed highlights, for instance, tend to go Cyan. Using editing software you can choose to keep it, change it or remove it. LifePixel has some simple tutorials on their website for that sort of thing. A little research on the internet will find more examples of how to work with an infrared image after capture. As with working on any other image, you’re only limited by your imagination.

The actual mechanics of shooting the camera are the same except for exposure and autofocus. I’ve found that I almost always overexpose or underexpose by up to one stop. Checking the histogram and highlight alert on the back of the camera makes it easy to judge which way to go. Also, while autofocus still works, it tends to work best with wideangle lenses. Infrared has a different focus point than non-infrared. With wideangles and a bit of depth of field you probably won’t notice, but you’ll need to experiment with your telephotos to see how much in front or behind you need to focus for sharp images.

I’ve always loved photography for the seemingly endless choices it gives me in areas to play with and explore. Next time you’re ready to replace your current digital camera with one of the newer ones, consider giving the old one a new life. Get it converted to infrared and open the door to a whole new way of seeing and capturing the world.