What do you know about Infrared Photography in an investigation?
Can you recommend a Full Spectrum Camera?
Good Question! Let's cut through all the hype and get down to some real answers that might surprise you!
When it comes to paranormal investigation Infra Red or full spectrum cameras seem to be on many investigator's want list. But there are several considerations before you run out and start taking pictures. The problems break down into two areas, equipment and methods.
Figure 1 - The Spectrum
To understand I.R., and for that matter U.V. photography, you need to understand the nature of each. Both are closely related to visible light, it is only their respective bandwidth that makes a difference. Refer to Figure 1. The top portion shows how the visible light portion of the spectrum and the Infrared and Ultraviolet relate. The wavelength of each, in nanometers, is shown below the spectrum. You can see that Infrared and Ultraviolet are simply an extension of the visible light portion. It sounds simple, but this extension also creates a problem for a camera.
All light, Infrared through Ultraviolet can be focused through a lens. But no single lens can cover this wide of a bandwidth. Normal glass appears clear to visible light but becomes quite opaque as the wavelength increases deeper into the I.R. spectrum. Light behaves differently as it passes through such lenses. However there are materials which do allow I.R. to pass. The problem is these work poorly at the shorter wavelength visible light and almost completely block U.V. Likewise different materials work great in U.V and are worthless in I.R. No one material is good for all. The solution is multiple lenses, one for Infrared, another for visible light, and yet another for Ultraviolet.
Which by now you probably notice, shoots a big hole in the idea many investigators have of a full spectrum camera. No single camera can cover a "full spectrum" properly. You will get poor quality, blurred, or false color pictures. These are also subject to various aberrations which lead to "ghosts" or other "paranormal" effects. The TV ghost busters are notorious for spreading these images on the shows because they look impressive and draw viewers. To do this photography properly You need a separate camera, or interchangeable lenses, designed for the intention you have in mind.
Another fallacy is the idea of "modifying" a camera by removing the I.R.Filter to make it into an night vision camera. It is true you can do so, but that filter is there for a reason. Take a look at the second section of Figure 1. It shows the typical response curve of a CCD imager in a digital camera. You can see that the imager does respond to I.R. as well as visible light. To that extent you can remove the filter and it will work. But you also must replace the filter with one that blocks visible light, otherwise light present outside the spectrum you are viewing will alter the exposure settings. And while you are at it, as discussed previously, the lens will need changed to one intended for I.R use. So unless you are willing to make these modifications as well, best thing is use the camera as intended, for visible light photography.
Another problem when the filter is removed is color balance. The CCD imager is designed to compensate for the effects the filter introduces into the visible light spectrum. Removing it changes the overall response of the imager. Compare the two response curves in Figure 1. The region in the I.R. spectrum was compensated for by the imager. Now if all of a sudden I.R. is allowed in obviously the average response bandwidth has shifted downward. Color may be incorrectly rendered.
One more thing is illumination. Many want to use I.R. LED illuminators. This is fine but keep in mind that having one of these in operation also sets up a perfect condition for reflections that you may not be aware of. Any reflective object in the room will bounce the I.R. light back just like a mirror. So keep that in mind when you suddenly see that bright orb in the picture that you know wasn't present when you looked. This is a common problem many overlook when they work with Infrared or night photography. You can get orbs in your pictures very easily even without flash under these conditions.
Also be aware that different materials react to light based on its wavelength. You have seen those iridescent shirts that glow brightly under "Black Light". Imagine what a piece of airborne lint from one of those would look like in a dark room if it passed near your illuminator. And you got a picture of it.....(Seen quite a few of those "Best Ever Videos)
So does all this mean I.R. Photography is to be avoided when investigating? Not at all. The trick is if you are going to use it, do it correctly. Use the appropriate lens on your camera. Be aware of the problems unique to working outside the visible light spectrum. And do what you can to minimize anomalies, especially when illuminating the scene. One way to do that is utilize a modification of a standard photography technique called Bounce flash. Instead of trying to make your narrow beam reach extreme distances, point it toward the ceiling or a reflective screen. This causes a more diffuse illumination that eliminates most strong shadows. You get a better balance of exposure across your field of view, and if anything is there it will be a more true representation of itself.
Also be aware that there is absolutely no solid proof that a ghost or spirit is seen any better under infrared or ultraviolet than it is under visible light. The only reason this is a popular belief is because the number of false positives is much higher under these methods, thus a lot of unsubstantiated claims. So if you are working in these regions be especially critical of any results you get.
I was also asked what I feel is the most important way to utilize I.R. in investigative work. To respond to that I would have to say in cases where claims are made of being scratched or otherwise affected by spirits. I have set up video with infrared illumination to observe a subject while sleeping to see what caused the scratches. I have identified the cause on several occasions; The person scratched themselves while sleeping unaware. The I.R. System allowed for observation without disturbing their sleep, unlike conventional lighting. They were also unable to deny what happened when they were shown the video of them the next day. Thus one of the key uses is to resolve claims of paranormal activity and provide objective evidence of that explanation.