Many digital cameras are sensitive to light in the infra red part of the electromagnetic spectrum. This is found at wavelengths just below visible red and cannot be seen by the naked human eye. Television remote controls use the same wavelengths.
Taking pictures in infra red needs a suitable filter, a slightly different technique, and a tripod.
To allow the camera to “see” infra red you need a filter to remove visible light from the image. These are available in threaded glass for SLR cameras, but many digital cameras do not have a suitable screw thread on the lens.
I use an Ilford SFX P (Cat 190 6473 by Ilford Imaging UK Limited, Mobberley, Cheshire) which is a piece of stiff plastic some 75mm square. For my current experiments I simply hold the filter in front of the lens and light sensor, although for my Canon G3 I have made my own threaded adaptor based on a UV filter.
Use of a tripod is absolutely essential as the exposure time is quite long.
You will need to experiment with your shots as they will look very different under infra red light. Some details are highlighted and others are lost altogether. Try to avoid dull overcast days. Lots of sun is best!
I have found best results are obtained by using the camera in manual mode:
- Use the highest ASA setting.
- Manual focus – activated.
- Camera display screen – on.
- Timer – activated, to avoid camera shake when pressing the shutter.
I have not had particularly good results indoors, although tungsten lighting seems to be better than flourescent, presumably because it has a higher infra red content.
I have posted a few of my pictures in the Gallery Page. Have fun!
Note that this technique will not allow you to take those multicoloured shots of heat loss through your house walls and such like. These use infra red of even lower wavelength and need special apparatus.