Very often infrared images can make the ordinary look mysterious and interesting. In Figure A, you can see an image of a park shot in infrared. In regular black and white this picture wouldn't be very remarkable, but in infrared it has a spooky, surreal quality that catches your attention.

Figure A: An ordinary city park can become a mysterious place under infrared.

Before digital cameras, shooting infrared images with film was something of a crapshoot. You didn't really know how a scene would turn out until you got the film back. Since you can't see infrared radiation, you never really knew what the object would look like or if you even got the correct exposure. With digital cameras, infrared imaging is far easier because the camera's LCD shows you the results instantly. You can see how objects look and know if you're in the ballpark of a correct exposure.

Digital Infrared Imaging
We'll give you an overview of infrared imaging, starting with some background information that will help you understand infrared radiation and its effects on the imaging process. We'll also show you how to determine if your camera is capable of making infrared images and go over the necessary gear that you'll need to accomplish the task. Finally, we'll cover some Photoshop techniques that will help you get the best results from your images.

What Is Infrared?
Infrared radiation (IR) is a small band of the electromagnetic spectrum that falls between visible radiation (light) and microwaves. Because it's slightly longer in wavelength than light, we can't see it. It ranges from about 700 nanometers (nm) to 1 mm, where as light ranges from 400 to 700 nm.

Infrared and ultraviolet radiation lay on either side of the visible spectrum, as you can see in the diagram in Figure B. Though we can't see either infrared or ultraviolet, both can be used for imaging purposes because film and CCDs are capable of recording them.

Figure B: Infrared radiation is slightly longer in wavelength than light.

Heat on a Different Scale
Basically, IR is what we interpret as heat, but in reality it's on a totally different scale. Scientists base heat off 0 degrees Kelvin, also known as absolute zero, which is the temperature at which molecules stop moving. The Fahrenheit equivalent of absolute zero is -459.4 degrees, so you can see it's extremely cold. Therefore, everything above absolute zero has some amount of heat.

In reality, that heat is just IR given off by the moving molecules. As the molecules move faster, they give off more infrared and the object is perceived to be progressively warmer. The warmer the object, the more infrared it emits. An electric stove element is a good example of this. When you turn on the burner, you can feel the coil giving off IR before it turns visibly red. As the coil gets hotter, the wavelength of the radiation continues to shorten and eventually we can see the element turn red as some of the radiation speeds up to the visible range. This is called the point of incandescence. As an object continues to get hotter, it releases light and eventually ultraviolet radiation. This is the case with stars such as the sun, which gives us all kinds of light-as well as plenty of infrared to make shooting outdoors fun as well as warm.