Digital Photography Technology

Infrared photography is a unique type of photography where pictures are taken with light that can not be seen. Infrared photography is above the visible light spectrum, but sensitive to IR film and CCD and CMOS sensors in digital cameras. The frequency range of IR is 700 to 900 nanometers (nm), and the visual light spectrum is 400 to 700 nm. It is also referred to as near IR. IR has the ability to see what visual light can not see, such as being able to looking through haze with a telescope.

Infrared photography was not used in the early years of photography because the silver halide emulsions in film were not sensitive to IR. Robert Wood was the first person to use IR in 1910 by using a dye on the film sensitive to IR. The speed of the film was very slow, so long exposures were required and the first pictures were of architecture and landscapes. IR was starting to be developed during World War I, as it was found to very useful for aerial photography. Professor Robert Wood, who was a physicist at Johns Hopkins University, has been considered to be the father of infrared and ultraviolet photography.

Focusing IR has to be understood before you can start taking pictures, as it focuses differently than visible light. Any lens will focus infrared, but the lens has to be adjusted differently. Many older manual lenses have a mark showing the distance when the object is in focus, and a red mark for IR. Move the distance setting to the red mark. Now the camera is set to take IR pictures. Another way to help keep the subject in focus is to stop the lens opening down for more depth of field.

What type of camera takes the best IR picture? Most types of film cameras will take IF pictures. There are a number of manufacturers that make IR film, both black and white and color. A filter is need in front of the lens to keep visible light from reaching the film. A deep red filter will work and an opaque filter is available that will only pass IR, but if very expensive. Then there is the problem when using these filters with an SLR camera that you can not see through the lens when focusing or viewing the object you are taking the picture of. The filter has to be removed; the adjustments made, then replace the filter and take the picture.

DSLR cameras have a different set of problems. Due to the fact that CCD and CMOS sensors are sensitive to IR, digital camera manufacturers place a filter in front of the sensor to keep IR out. The pictures will take on a hazy look if the IR is not removed. There is a small amount of IR that does get through, but with a filter, the exposure time gets very long. A tripod must be used and there is the inability to shoot any action.

To counteract all these problems, there are companies that will convert many DSLR’s to a true IR camera by removing the IR filter in front of the sensor, and installing a filter that will pass IR only. The camera will only take IR photos, but they can now be viewed through the ground glass for focusing. Hand held action shots are now possible, in color or black and white. Some cameras have the ability to shoot black and white, and if they don’t, the IR files can be converted to black and white in one of the many software programs available.

Exposure is the most difficult part of IR to understand and put into practical use. Also, the equipment that you are using will make a difference. If a filter in used front of the lens, long exposures and using a tripod will be required. If the camera has been converted to IR only, the camera can be hand held. With the advent of digital, very little IR film is being used, as it is so easy to take digital pictures, and then being able to examine them immediately. Exposure is a trial and error, but the more pictures you take, the better you will become. Examine the histogram, bracket, and take a variety of different subjects. Experiment with all the different settings on your camera, as there is no set way to take an IR picture.

There are many books available on the internet to read and they will go into great detail on IR. You will find IR fascinating as to the wide variety of results that you will get, and there will be many surprises.