Animal Magnetism
The Spider that Devoured Switzerland

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The Spider that Devoured Switzerland

Most people who see this image immediately assume it's a montage. It isn't! Now the spider isn't really bigger than the buildings, of course, but it's still respectably large: about three centimetre leg span. It had set up shop outside an east facing window of the Fourmilab conference room, deploying its web to snag insects attracted by interior lights at notoriously late-working Fourmilab.

Walker's Second Law of Spiders goes as follows. “Any spider, regardless of size, will appear at least three times bigger if you unexpectedly spot it at eye level.” I took this picture to illustrate the phenomenon. Selecting full manual mode on my Olympus digital camera permitted choosing the smallest lens aperture available, f/10, with a slow shutter speed of 1/30 second to obtain the correct exposure. I can usually get away with hand holding a camera at 1/30, but in this case I used a tripod just to be sure. The spider didn't move at all, which made composing the shot quite easy. With such a small aperture, the hyperfocal distance is such that both the spider and the distant scenery are (more or less) in focus—this image suffers more from JPEG ringing artefacts at bright/dark transitions than accuracy of focus. The spiderweb, visible to the eye, eluded capture by the camera due to limited resolution and lack of contrast against the bright background. The spider appears almost in silhouette against the sky; attempts to use fill-in flash resulted in a dazzling flash-back reflection from the double paned window. I don't know the spider's species. I asked, but it wouldn't tell me.

This photograph was taken by John Walker in July 2002 from a window at Fourmilab with an Olympus C-3040 digital camera at f/10 and 1/30 second.

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by John Walker
July 10th, 2003
This document is in the public domain.