Unlike normal photography, infrared (IR) photography usually does not contain much colour. Ideally the photographer should do a custom white balance of the scene when using an IR-converted digital camera because automatic white balance often results in images that have a reddish or purplish colour cast. It is usually considered correct to do a custom white balance by measuring white balance on green grass/leaves on a sunny day. This white balance measurement renders the IR image looking similar to black and white images.
If custom white balance was measured on something else, say blue sky or red brick, the resulting IR image may contain some rather strange colours. This colour is called “false colours”, and some photographers like it. Predicting the occurrence of false colours is difficult because it varies between digital camera models. Based on research and experience, some digital cameras do not produce false colours. The appearance of false colours also depends on how the custom white balance was done.
In June 2010, I shot some IR images using an unconverted Canon PowerShot A650IS with a Hoya R72 filter held in front of the lens, and was surprised to observe that it does not produce the hot spot flare in its images. Its smaller brothers, the A630 and A640, also do not produce the hot spot flare when shooting IR images.
In July 2010, I shot more IR images using my specially-modified Canon PowerShot SX120IS with a 680nm infrared filter. Shot at Mount Buller and at Echuca, it was at Echuca that I discovered the custom white balance I did using a 950nm infrared filter tended to produce a sepia-tone appearance in images shot with a 680nm filter.
Some of the images shown were not post-processed, but some have been enhanced to improve visual appearance.
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