Digital infrared
Ξ February 1st, 2008 | → 0 Comments | ∇ Techniques |
THE world of infrared is very different to anything we have ever seen and with good reason – it’s invisible to the naked eye. Infrared is merely a band of the light spectrum that is past that of visible light, so our eyes cannot see it. But that does not mean we cannot capture subjects with a specially modified digital camera. This is not something new, but something that has fallen by the wayside with the onset of digital cameras.Back in the days of film, you could buy special infrared-sensitive film that was able to record that part of the spectrum.With digital, because of the wide sensitivity of the digital chips, manufacturers had to put a band-pass filter between the lens and the chip to block infrared and UV light that would otherwise interfere with the image.The way around this is to have your camera modified. Wayne Rogers from the Camera Clinic removed the band pass filter (also called a hot mirror filter) from my old Nikon Coolpix 5400 and replaced it with a full spectrum filter. This allows both infrared light and UV light to pass through. If you want to record only infrared light, you can either have an infrared filter (opaque red) fitted internally or use the same filter over your lens. The difference is that the one over the lens can be removed, and a UV-only filter applied to record only the UV end of the spectrum.With my camera, I took the external filter option. When I turned the camera on, the images I was seeing on the LCD screen were very weird, with the colours being most unusual and not that impressive. Then I switched the camera to monochrome (black and white), which works really well with infrared light. Still not all that impressive. Then I placed the opaque filter over the lens (this filter lets only infrared light through — you cannot see through it at all). After an instant to adjust, the wishy-washy black-and-white scene was replaced by this awesome, spooky-looking infrared scene. The effect was amazing, in a word: Wow!Any vegetation reflects infrared light and therefore appears white, so trees and grass look as it they are covered in snow or frost.Water and sky reflect none, so they appear black and clouds stand out like never before. The most ordinary landscape now looks like something that has been captured by Ansel Adams himself.Despite popular opinion, infrared does not work in the dark, nor does it record heat. The military uses infrared sights on weapons for sighting at night, but they are equipped with an infrared light source (that is invisible to the naked eye). You can cover your flash with an opaque infrared filter that will allow you to take pictures at night without people seeing your flash (unless they are looking right at it when it fires). The effects of this are really spooky with people looking very pale, almost albino, with weird-looking eyes.Getting back to the film days, there were a couple of major problems. First, with the opaque filter in place you couldn’t see what you were getting, so a tripod was mandatory. And even then you didn’t really know what you were getting until you developed the film. Second, the film was so grainy that it was awful. Even at ISO 25, it had the equivalent grain of ISO 1000.Now that we have managed to digitise the operation, things have improved out of sight (pun intended).The main difference is that now, with a point-and-shoot digital camera, we have live view on the LCD screen, so we can see exactly how the image will look in infrared.We can shoot hand-held with no need for a tripod. And finally, the grain issues of film don’t equate to noise issues with digital. The digital infrared has minimal noise and is therefore much clearer than the film version. Also, the tonal values are superb, giving the type of results you would expect to see in a fine-art gallery.Wayne from the Camera Clinic tells me that they have modified a few D70 digital SLR cameras and even a Canon 1D, but the problem with this type of camera is the lack of a live view, meaning that with the filter in place you cannot see through the viewfinder, so a tripod is necessary. The other problem is that the camera will be unusable for normal photography after the conversion. This is a not an operation that a lot of people will have performed on their camera. But for those who like the artistic side of photography, or even those scientifically minded, it will be a huge bonus.It allows us to really look at things differently and will cause you to rethink the way you take photographs. An ordinary landscape can be spectacular in infrared, just as a really interesting scene can be thoroughly boring when shot in infrared. If you have an old camera that you are prepared to sacrifice to the part of the spectrum that we cannot see, have it modified and go out and capture this exciting wavelength.Even though we cannot see infrared, it will really open your eyes. For examples of this technique have a look at the digital infrared section in the galleries.
