Introduction
Near infrared light consists of light just beyond visible red light (wavelengths greater than 780nm). Contrary to popular thought, near infrared photography does not allow the recording of thermal radiation (heat). Far-infrared thermal imaging requires more specialized equipment, and is not the subject of this tutorial. Infrared images exhibit a few distinct effects that give them an exotic, antique look. Plant life looks completely white because it reflects almost all infrared light (because of this effect, infrared photography is commonly used in aerial photography to analyze crop yields, pest control, etc.) The sky is a stark black because no infrared light is scattered. Human skin looks pale and ghostly. I have a photograph of a friend's black shirt, which looks white in infrared. My dark sunglasses all but disappear in infrared because they don't block any infrared light, and it's said that you can capture the near infrared emissions of a common iron.
Infrared photography has been around for at least 70 years, but until recently has not been easily accessible to those not versed in traditional photographic processes. Since the charge-coupled devices (CCDs) used in digital cameras and camcorders are sensitive to near-infrared light, they can be used to capture infrared photos. With a filter that blocks out all visible light (also frequently called a "cold mirror" filter), most modern digital cameras and camcorders can capture photographs in infrared. In addition, they have LCD screens, which can be used to preview the resulting image in real-time, a tool unavailable in traditional photography without using filters that allow some visible (red) light through.
This tutorial will take you through all of the steps necessary to procure and manipulate near infrared photographs through the use of a digital camera (or camcorder). You will need:
- a digital camera
- a Kodak Wratten #89B, #88A, #87, #87B, or #87C filter
(in order of how much visible light they block, from low to high)
- a tripod
- a means to fasten the filter to your camera
- an image editing program such as Adobe Photoshop
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Fig 1. Filter, step-up rings, lens hood. |