On 3rd October 2005, Europe, Africa, and Southern Asia experienced a solar eclipse. In Portugal, Spain, Libya, Sudan, and Kenya this was visible as an annular solar eclipse, which is where the moon doesn't completely cover the sun and leaves a ring. I'm in the United Kingdom, where only a partial eclipse was visible.
First I decided to take some projection photographs with binoculars, much like my ones of the Venus transit the year before. But these didn't come out very well, so I decided to take the opportunity to look for a phenomenon that I'd heard of whereby the gaps between leaves in trees act as little lenses, by diffraction, essentially becoming pinhole cameras. During times of eclipse, these images are scattered around whatever lies around the trees, as long as they're at the right angle.
So I went outside to the nearest tree, but it wasn't casting any crescent images that I could find. But I went on to the next nearest tree and voila! Lots of crescents:
When I looked around more and more I found that they were everywhere; the area was absolutely replete with crescents. I spent quite a while photographing the more interesting ones and looking for other sources of diffraction, and then went home. When I was back home I thought there probably wouldn't be any more sources indoors, but I was wrong: even the holes in our net curtains were casting thousands of little crescents. So I thought, hey, if holes of that size can make some pretty decent crescents, what if I made some holes of my own in a piece of paper?
So I got a few pieces of paper and made some pinholes in them into various patterns, and then held them roughly 5–12 inches from another blank sheet of paper. According to Wikipedia the optimal pinhole diameter, as devised by Jozef Petzval and Lord Rayleigh, is 1.9 × √fλ, and Google tells me that 1.9 * sqrt((20 cm) * 550 nm) = 0.63015871 millimeters. Though I didn't measure the holes, they were roughly that size or a little bigger.
It was difficult to get the angles of the paper right and photograph them at the same time, but once I did I managed to make some interesting pieces of eclipse art including a spiral:
Having tried a crescent and a star which didn't photograph all that well, and a crescent shaped spectrum cast by a prism which also didn't come out great, I managed to take a fairly good image of my initials in crescents:
I was thinking of using it on my homepage or something like that, but it's not really heading material so I thought I'd use it as an illustration of what I did, instead. Though the natural photographs of the curtains and the trees casting the crescents are better, I like the synthesis of nature and man-made elements that went into the eclipse art, and I'll bet a real artist could come up with something much better.
Indeed, I wonder if eclipse art of this kind has been done much before? I presume it must have been, but a quick search on Google didn't reveal anything other than paintings and so on of total eclipses. If anybody knows of anything like this, or if you've tried it out yourself from having read this article, do please let me know!Sean B. Palmer, inamidst.com