Tuesday, 25 August 2015

Strange white streaks photographed

White trailsThe photo here (right), taken recently, is a rather blurry picture of the leaves in a tree. Despite the blurriness it is possible to make out individual leaves. But there is something more mysterious in this photo. There are several vertical white streaks. The best examples are two streaks in a dark patch just above, and to the right of, the centre of the frame. They look sharp, in contrast to the leaves around them.

I've seen many anomalous photos which are blurry. It can be difficult to identify the cause of anomalies in such photos. However, I know what these particular streaks are because I came across them when experimenting with deliberately blurring photos. There are two main causes of blurring in photos - being out of focus and motion blur. This photo is caused by motion blur - the camera had a relatively slow shutter speed (1/5s) and was moved slightly during exposure.

The white streaks are small patches of sky showing through the canopy of leaves. On a non-motion blurred photo they would show up as white dots. But when the camera moved they became white streaks,. They appear to be sharp because a dot forms a line when stretched. Leaves, on the other hand, just become fuzzy. I have to admit, had I never done this experiment, and I was presented with a photo like this, I would be puzzled by it. It shows the value of such xenonormal experiments.

1 comment:

  1. My first thought, before even finishing reading the first paragraph, was that the streaks were just sky showing through. Seems obvious to me.