Monday, 21 December 2015

Strange object with a tail

Weird lkems flareI took this photo (right) of a strange apparently luminous object recently. It appears to have a tail bending off to the right. It turns out that the explanation for this particular photo could apply to a whole range of similar strange objects photographed in low light.

At first sight, it isn't obvious what the explanation is. There was no actual aerial object seen at the time of exposure. However, the strange object could be seen clearly in the viewfinder of the camera. That's because it's lens flare.

Lens flare isn't the most obvious explanation because the shape is asymmetric. Most lens flare produces symmetric shapes. The reason this lens flare is asymmetric is that it has been elongated by camera shake. The exposure time was 1/4s. The camera shake isn't obvious because the bush in the bottom right corner does not show noticeable motion blur. Now does the post supporting the street light on the left.

Less strange lems flareCompare the photo (right) of the same scene taken at the same time (or 16s later to be exact). The same lens flare is present but it is now a more familiar symmetric elliptical shape with no tail. This is how the lens flare looked at all times through the camera viewfinder. The exposure time is also 1/4s but I clearly held the cameras more steady for this shot. The bush does not look motion blurred in this photo either. So what's going on here?

I realised the answer as I looked through the viewfinder while taking these photos. As I panned across the scene, every object in the static view 'moved' at the same rate with one exception. The lens flare moved noticeably more quickly than all the real objects in the photo. The degree of blurring in a photo is proportional to the angular speed an object is moving at in the scene. Obviously, there are no physical objects moving in this photo but the camera shake made them appear to move, like a sort of unwanted panning action. And the one object 'moving' much faster than the others in this static scene was the lens flare.

So, we have here a likely xenonormal explanation for many such similar anomalous photos. Lens flare can no longer be ruled out for not looking asymmetric.

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