Swing on this

The Foucault Pendulum in the central rotunda of Griffith Observatory. This 240-pound ball swings on a cable over a this circular pit with a lighted ring around the perimeter.

Here's two virtually identical shots of the ball. Both use the same aperture setting (F/3.5, for the photographically inclined).

Here's what it looks like with a 1/15 second exposure:


Here's what it looks like with a 1/125 second exposure:


Hey look: That lighted ring is divided into 42 sections (numbered 0 - 41). All because we let the lens be exposed to the light for 1/110th of a second less (shorter than the blink of an eye).

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"Photo" means light, doesn't it? Imagine that: Photography depends entirely on light.

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These were taken during a trip to the observatory back in January. In case I haven't shoved it down your throat enough, I'll point out that there's more shots from that day over at the photo site.