File:Visible and IR spectrum response of Olympus C-2000 Z.jpg

English: Four images showing the Olympus C-2000 Z (C-2000 Zoom) camera's response to varying wavelengths of visible and infrared light.

• Top left: Visible light (diffraction filter only)
• Top right: Circa 720nm cutoff (Cokin A007 (Wratten 89B 720nm compatible) in front of diffraction filter)
• Bottom left: Circa 850nm cutoff (No-name 850nm filter in front of diffraction filter)
• Bottom right: Composite with all three images overlaid. This could not be taken as a single shot and is only intended to illustrate the relative position and colour responses of all three images next to each other. Note that the diffraction spikes are not aligned across shots; this is good, as it's easier to differentiate the non-overlapping spectra.
  
  

All three were taken at the same focal length (but not at the same speed/aperture settings) with a Hoya "Nebula" diffraction filter held in the same position- as close to the lens as possible- in all cases. Where the IR filter was used, it was placed in front of the diffraction filter. The images have not been modified beyond cropping and alignment.

(This filter tends to give much fainter secondary spectra, but these should be minimal here).

The main purpose of this is to gauge what the colour response means when using the 720nm filter (top right). We can see from the visible light image that longer (redder) wavelengths go on the outside; thus the "red" parts on the 720nm IR image are actually the shortest wavelength (just outside/overlapping far red visible light) and the parts which *appear* blue here actually represent longer wavelengths(!) In practice, most shots contain more "red" than might be expected from this, which implies it's more sensitive to those wavelengths and/or their relative strength.

This is only a rough test as to how one specific camera model renders IR colour using specific filters. We can't read more into it than that; it might apply to other cameras, it might not.