Friday, 24 January 2014

See multiple orbs morphing into dust!

Group of orbsI've long held an ambition to video an individual piece of dust morphing into an orb (or vice versa). Last month (here) I managed to show orbs and dust morphing into each other but it didn't quite fit what I'd seen in my imagination. The problem was that the dust particles, when in focus, were getting stretched out into light trails by motion blur. I still wanted to show a recognisable bit of dust turn directly into an orb without any such blur. And eventually I got lucky!

So what's in the video (which is here)? What you see is a torch with the far edge in focus but the nearer one not. Dust is floating around strongly illuminated. When they are out of focus, because they're too close to the camera (and inside the orb zone), dust particles appear as orbs. In the grab shot (above right) from the video you can see a tight group of overlapping orbs.

Dust particleLater, as the group of orbs drift away, they leave the orb zone, come into focus and are revealed as a single large dust particle. It is a fibre (pic right), a typical component of household dust. Because the fibre is drifting directly away from the camera, it is not motion-blurred into a light trail.

This video illustrates how orbs are not simply out of focus objects, they are out of focus highlights ON objects. This is why one fibre of dust becomes at least three overlapping orbs. However, the vast majority of dust orbs seen are singletons. That's because most dust particles are much smaller than the one shown here. They are so small that they only contain one highlight! Large bits of dust, like the one in the video, rarely form orbs because they quickly fall to the floor.

Another interesting thing to note is that the dust fibre is rotating. This means that the highlights shift around as different surfaces of the object are presented to the camera. In the video, the number of orbs in the group actually changes and they alter relative position, all due to the rotation of the dust fibre. Though dust rarely produces groups of orbs like this, insects commonly do because they are larger and generally have many highlights. In the video, the dust fibre finally vanishes because it leaves the orb zone. Though still in focus, it is no longer strongly illuminated by the torch. See here for more on exploring the orb zone.

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