“I think that I shall never see,
A poem lovely as a tree…” – Joyce Kilmer
On May 20 an annular eclipse graced the skies over Northern California for a rare celestial treat. An annular eclipse doesn’t cover the sun completely the way a total eclipse does. In an annular eclipse, the moon is at its farthest point when it comes between the Earth and the Sun, so it doesn’t completely cover the sun. In the prime viewing areas, the eclipse appears as a firery ring. Stockton was just out of the optimal path and experienced a partial eclipse, but still about 90% of the Sun’s disk was covered by the moon.
Viewing any eclipse without proper eye protection is dangerous. Even with the sun partially covered, it is so bright that looking at it with the unaided eye can cause immediate and permanent damage.
The Stockton Astronomical Society held a special eclipse viewing party in an empty lot along the Stockton Waterfront. They had several telescopes specially outfitted to block out the harmful rays of the sun for the curious to view the eclipse safely. They ranged in size from about 1-½ feet long to seemingly near Howitzer proportions. Most looked pretty pricey, too. Even my rig that I used to photograph the eclipse was expensive. I used a Nikkor 200-400mm lens with a 1.7 telextender with was about the equivalent focal length of 650mm. I attached it to a Nikon D300 camera. With its 1.5 crop factor due to its smaller sensor size, the whole thing worked out to be about the same as a 975mm lens relative to a full-frame camera.
But there are cheaper alternatives at the viewing party as well.
The coolest of which was called a Sunspotter, a wooded device shaped a bit like a sextant that, through a series of mirrors and lenses, created an image of the sun on a white piece of paper.
Society members also handed out special eclipse viewing glasses to the viewing public. Much like the old cardboard 3-D glasses given out with comic books, the lenses were made of dense mylar (I used a pair to help aim my camera towards the sun). They were useless for anything but looking at the sun but provided a clear and way to look at the eclipse directly.
Stockton Astronomical Society member Albert Liang not only had his own rather impressively big telescope rigged up, but he also brought along a viewer that he made himself. It was a small cardboard box about the size of a shoebox. In one end he poked a pinhole that, when pointed at the sun, projected its image on the inside bottom if the box. He cut away one side of the box so that people could look in to see the small projected image of the eclipse. It was the same principal of a pinhole camera or a camera obscura, where a small hole is the lens and aperture.
Just after the eclipse reached its height and I finished my shooting, I headed back to my car. On its surface I saw dozens, maybe hundreds, of small replicas of the crescent sun. The nearby tree that I had parked under to shade my car from the heat of the sun’s solar rays acted much like Liang’s small pinhole projector. The small gaps that normally created dapple sunlight patterns became lens/apertures and focused images of the eclipse on whatever the light touched.
So the next time an eclipse happens (the next one in North America is scheduled for Aug. 21, 2017) make sure to protect your eyes. One way would be to make a pinhole creation like Liang. Or easier yet, just find a nearby tree.