Tuesday, 1 July 2014

Stumped by an owl

Ghost owlWalking through a wood recently, as you do, something caught my attention. I couldn't see it very well in the gloomy lighting conditions but I was sure it was something interesting. In fact, I was sure it was a living creature of some sort but I wasn't sure what. So, I took a photo of it (right). When I examined the photo later, it looked like an owl, standing on the ground. I also took a second, zoomed, photo of the object at the same time, experience having taught me that this is a very useful thing to do.

Owls are always tricky to see, even for experienced birders. It isn't just their generally nocturnal habits, they are also surprisingly unobtrusive for a large bird.

I was disappointed, when I later examined the zoomed shot, to see ithat the 'owl' was, in fact, a small tree stump (see photo below right ). Once I got over my disappointment I realised there was, after all, something rather interesting about this 'owl' observation.

Owl stump I only ever saw the object as an owl in the first photo, not in my simultaneous naked eye view of it. Now the vast majority of photographic anomalies are only seen after the event, in the photo itself. I have often thought that if the observer was able somehow to go back in time and examine the scene again carefully with their naked eye, they would NOT see any anomaly there. This 'owl' observation tends to support that idea.

So why did the object only appear as an owl in the first photo? The stump is certainly the right approximate shape, size, colour and pattern for a Tawny Owl. There is even a suggestion of a 'facial disk' and a dark 'eye', on the left side of the 'head' exactly where you would expect one, in the upper photo. And yet, I saw no 'owl' at the time with the naked eye. Why not?

A crucial point, I believe, is that the 'owl' in upper photo is out of focus. In contrast , it is IN focus in the lower photo and would have been to the naked eye too. In fact, we almost never see anything out of focus with the naked eye because our eyes are constantly changing focus as we look around any scene.

So the 'owl' has come about because of a difference between the way the naked eye and a camera works. If I look at the stump with my naked eye, I automatically focus on it, and see no owl. However, the camera has focussed on the vegetation in front of the 'owl', so putting the background out of focus. It is, thus, an example of a photographic artefact, like so many anomalous photos. And that, I think, is why so many photographic anomalies are only seen on the photo itself, not by witnesses at the time of exposure.

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