Wednesday, 8 May 2013

It just appeared!

Branch web 1I have noticed that a rarely mentioned class of anomalous photo appears to be becoming more popular. The 'class' is best described like this: an object appears in one photo but not in another. The two photos are of exactly the same scene, taken from the same position and were shot just seconds apart. There are two subclasses of this type of photo. One is where the 'object' is anomalous, like an orb, ghostly mist or flying rod. The other is where the 'object' is simply an unremarkable, everyday sort of thing. The photo pair is usually considered anomalous because the photographer cannot see how the object could have just appeared, or disappeared, in a matter of seconds.

In the case of an apparently anomalous object, there is a common cause linking most such examples. It is that the specific conditions in which such an anomaly, or photographic artefact, appears are strictly limited. For instance, objects only appears as orbs inside the orb zone, a relatively small volume just in front of the camera. Bits of dust can easily drift in and out of the small zone within seconds. With flying rods, the insect needs to be in focus but close enough to the camera to appear as a rod. Again, this is a relatively small volume of space in front of the camera which flying insects can enter or leave quickly. In the case of ghostly mists, these are usually caused by the photographer's own breath becoming visible on cold nights when illuminated strongly by the camera's flash. To show up in this way, the breath needs to be close to the camera. So close, in fact, that is out of focus, making less obviously recognizable.

Branch web 2With non-anomalous objects, the reasons why something should be visible in one photo of a pair, and not in another, are more varied. Take the example in the photos shown here. The top two pictures, which are both cropped from larger photos of the same scene, were taken 10 seconds apart. The lower photo is slightly blurred due to camera shake but there is also a much more obvious difference. Only the lower photo shows a clear linear diagonal light 'anomaly' in the upper third of the shot, midway between the left and right edges of the frame.

The 'anomaly' is caused by the sun reflecting on a strand of a cobweb. If you look carefully at the upper photo, you can see a bit of the same strand nearer to the tree branch, though much less bright. So what happened in those 10 seconds to make such a bright reflection (which requires direct sunlight) suddenly appear? The sun could certainly not have moved in the sky enough to produce the effect in such a short time. Nor was there any wind to move the branch. If you look at the whole, uncropped version of the upper photo there is a big clue!

RobinAnd here is that whole photo (right)! The cropped area is in the bottom right corner. And look, there is a Robin sitting on the branch that the web is attached to! Though the bird is in exactly the same position in both photos, it flicked its tail between the two shots. It was enough to move the branch slightly! Comparing the two photos closely, the branch is slightly higher (when compared to the background) in the second shot. In other words, it is in a slightly different position, compared to the sun. It is enough to allow direct sunlight to hit the previously shaded cobweb strand. It is just such slight changes that can make something visible on one photo and not in another, taken seconds apart. If the Robin had not been visible in the frame, the cause of this particular change would have remained a mystery!

So, why are people taking multiple shots of the same scene seconds apart? I don't know but I can speculate. It may be to get a comprehensive record of an important event. Or it may be to get at least one good shot by taking many. Whatever the reason, this still rare phenomenon appears to be on the increase!

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