Experiments with Infrared

Infrared (IR) photography is not new, last year the Royal Photographic Society (RPS) celebrated the centenary of IR imaging with a small international exhibition showing images from 1910.  You can view a copy of Professor Wood’s 1910 Article, Photography by Invisible Rays, by clicking here (PDF 3.34MB).

The sensitivity of the image sensor within modern digital cameras incorporates visible light and extends into the longer wavelength infrared. Camera manufacturers place a filter in front of the sensor to exclude IR to give a more balanced, colour correct visible light photograph. There are different approaches we can adopt in IR photography involving filters in front of the lens, but if we want to dedicate a sacrificial camera body which operates ‘as normal’ but in the IR band, the following approach is perhaps the best. We need to replace the existing filter directly in front of the sensor with a different one that excludes visible light and passes IR; there are specialist companies that offer this service. The camera will then operate ‘as normal’ with auto-focus, focussing point, auto-exposure and through the lens viewing all working as expected.

The photographs here were taken with a modified Canon 20d digital camera, I’ve included similar photos with different renderings to give you a flavour of what’s possible.  The RAW images from the camera are very red, first the white-balance needs to be corrected by setting it to as blue as possible (first image below), thus the foliage can be made white.  Very pleasing results are obtained when you then convert this to black & white and perform the usual processing for a standard B&W image.  Another common technique is to take the colour image and swap the red and blue channels, this yields the blue and white images that you see; to me they look a bit like the old cyanotypes.

Click me to see the Infrared gallery

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