I’m feeling more comfortable with making infrared images with my digital camera and I feel the results are showing an improvement reflecting that comfort. In the process I’ve also learned more about what you can do to make interesting infrared images. Some of it is equipment specific but much of it can be done with typical DSLR cameras.
First is the filter. There’s probably an infrared filter on your camera already, sitting right in front of the sensor. Its purpose is to protect the sensor from too much infrared light, which apparently will overpower it and render your exposures unusable. In addition to this filter you need an extra infrared filter, one that limits the light hitting the sensor to a range of wavelengths in the infrared region. I use the Hoya R72 filter, which allows light coming through starting at 720 nanometers. All you need to know is the smaller the number here, the more the light moves toward the blue end of the spectrum. At 720 and larger you’re getting infrared light.
Now comes the equipment specific issue. If your DSLR doesn’t have the ability to let you see what the sensor sees (it’s called LiveView on Olympus cameras) then you won’t be able to compose and focus with the filter on the lens. Your viewfinder will look black – all the “visible” light is being blocked by the filter. With the LiveView function, however, you see on the screen what the sensor sees – it’s sensitive to infrared light, remember? You can use the screen on the camera to compose the image and manually focus the lens (you have to turn off the auto-focus).
If you don’t have LiveView (or it’s equivalent) you can compose and focus through the viewfinder with the filter off the lens, then carefully put it back on the lens to make the image. There is a difference in focusing between visible and infrared light so you’ll have to play around to find where the “real” focal point lies for infrared.
How about exposure? Put your camera on manual and set the aperture and shutter speed separately. The filter cuts out lots of light so your shutter speed will be in seconds. You can reduce this time by using a higher ISO setting: doubling the ISO setting doubles the amount of light hitting the sensor, thus halving the shutter speed. The infrared image will look noisy due to the longer exposure so a higher ISO won’t be a problem.
How do you know you have a good exposure? Again, this might be camera specific. On my Olympus I can change the Info setting while viewing the resulting image to get histograms for the individual red, green and blue channels. What I look for is as much green and blue histogram to the right as I can get without blowing out the red histogram. It’s one great thing about infrared photography – you want bright, shiny days with lots of light.
Why the green and blue channels? Although the filter is blocking much of the light in this region, the sensor still records information during long exposures. The information in the blue and green channels is best for controlling contrast and detail in the final image so you want as much information in those channels as possible for post-processing.
With the image in-camera with the composition and exposure you want, what you’ll see is a very red tinted image that looks fairly flat without much contrast and detail. Now you turn to your computer to finish it off for that typical IR look.
With the image in Lightroom I increase the exposure and contrast to spread the histogram out. Then I move the image to Photoshop. I look at the image in Channels to see the differences among the red, green and blue channels. Using the Levels command, I select each channel separately and move the end sliders to meet each channel’s histogram, in the order of blue, green and red. After doing this for all three channels, I go back and adjust the mid-range slider for each to improve contrast. Now the image looks more dimensional, but it’s still colored (strangely colored).
At this point your options are to desaturate in Photoshop or return to Lightroom and do it there. I drop the image into a couple of NIK filters (Color Efex and Silver Efex) to bring up the contrast even more and to render the image into B&W. A little sharpening and the image is done.
What’s great about this technique is you can use it to process into a nice B&W image without going all the way to IR. For this I expose in camera with less blue and green, and then in post-processing not push the sliders as far. The result is the extremes between light and dark are less and the mid-tones are smoother.
Those are the basic steps I use to make and process IR images. There are other tools that work for processing but the making is going to be similar to what is described here on many cameras. The main thing is to make sure you get enough information in all the channels without blowing them out. Then you’ll have plenty to play with in processing.
I look for just before or after noon on sunny days with big puffy clouds. I like the dark sky contrasted with the bright clouds, along with the highlights at the tops of trees and ground foliage. The long exposure means wind will result in blurred objects where they move, but for me that accentuates the glow associated with IR images. Combine some wind, trees and immoveable objects that reflect a lot of IR and you can get some surrealistic images.