Digital infrared
From The Glossary of Digital Photography
An infrared image created with a digital camera. Digital image sensors are sensitive to infrared light. Many cameras have a built-in cut off filter to remove the infrared so that only visible light passes through to the sensor. Since infrared light focuses at a different point than visible light does, the cut-off filter removes the infrared light to keep the image from becoming blurry. To create a digital infrared image, a camera sensitive to infrared light (without a cut-off filter) needs to be used. Using an infrared television remote control pointed at the camera will enable the photographer to tell if the camera is sensitive to infrared. A special filter that passes only infrared and blocks all or most visible light is used on the camera lens to create the digital infrared image. This means that long exposure times, high ISO ratings, and lenses with apertures fully opened are generally needed. A tripod may be required as well. If the camera is not sensitive to infrared light because it contains a cut-off filter, the camera can be modified by removing the cut-off filter. See also digital camera (see figure on page 111)
