Wednesday, 3 October 2012

If it's close to the camera, it's probably not a ghost!

Photography, one of our most familiar technologies, can cause problems to those hoping to record paranormal phenomena. In particular, the distance of an object from the camera can have a huge bearing on whether it is paranormal or not.

While everyone knows about photos, few realize the many important differences between photography and simply viewing a scene with the naked eye. There is a list of some the major differences in the way cameras and the naked eye record images here. One thing that isn't mentioned there, which turns out to be the cause of many 'anomalous photos', is the difficulty of measuring the distance of objects from a camera.

Most people know that our two eyes give us a stereo view of the world but our brains do not rely solely on that mechanism for judging distance. With the naked eye, we judge the distance of an object by combining three different mechanisms. They are stereopsis, perspective and motion parallax.

With a photograph we obviously lose stereopsis as a way of judging distance (unless using a 3-D camera). But we also lose motion parallax. If an observer is moving while viewing a scene, objects nearby appear to move more quickly, relative to the distant background, than those further away. This effect, called motion parallax, allows us to judge how far things are away. Clearly, an observer cannot move relative the objects in a still photo (unless it's a hologram) so we lose this ability as well.

Gull and cormorantSo that just leaves perspective. Unfortunately, it is relatively easy to fool the brain with perspective, as illustrated here. So, in photos we rely on things like observing which objects are in front of others and their size relative to things of known dimensions. But even these methods can go wrong. We might see one object in front of another but we don't lnow HOW far is it in front. And what about objects that don't overlap? Or those taken against taken against the sky, like UFOs, or other featureless backgrounds? And what if we don't know the size of objects, even familiar ones, in the photo?

Take the photo, right, for example. Which bird is closer to the camera? It isn't possible to say, just be looking, given the fairly featureless background of the sea! As it happens, they are about the same distance. This is because the cormorant, the lower bird, is about 50% longer in the photo than the gull, which corresponds to their real relative sizes. As to how far they are from the camera, you'd have to use the methods of photogrammetry to work that out. These sort of techniques are not usually available to someone who just happens to have taken a ghost photo!

From studying thousands of anomalous photos, I've noticed that the commonest types are all semi-transparent objects in the near foreground. These include orbs, vortexes and many mists. All are so close to the camera that they are out of focus. However, this isn't always apparent because, as in the case of orbs, highlights in out of focus objects appear as relatively sharp transparent circles, rather than simply going fuzzy (see here). In many cases, these nearby objects are only visible in the photo because a flash has been used. But while they are always in the foreground, it can be difficult to tell their exact distance from the camera. Sometimes, perspective can make them appear far away when, in reality, they are very close to the camera. There are even cases where very nearby objects can appear to be behind other things in the photo (see here for an example). It is, however, an illusion caused by perspective. If we were watching such an object in real life, we could shift our position and see that one object was much closer than the other, using motion parallax.

Whenever you see an object in a photo which is transparent and in the foreground (usually, but not always, illuminated by flash), there's an excellent chance that it is a mundane object, like a dust particle or a camera strap, which is out of focus. With anomalous photos, if it's close to the camera, it's probably not a ghost! Though the camera doesn't lie, it tells a version of the truth that can mislead those not familiar with the way human perception works.

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