Monday, May 21, 2012

Partial Solar Eclipse

Amazing; over 4 months without a post. A combination of health, equipment, weather, and other issues meant that I've done very little photography so far this year. The upside is that I've had plenty of chances for visual stuff, but that doesn't produce anything to post.

This solar eclipse was seen an an "annular" eclipse in much of the country, but not here. An annular eclipse leaves a donut-shaped ring (an annulus) of the sun visible around the edges of the moon, and happens when the moon is far enough away that it's apparent diameter is smaller to us than that of the sun. The series of shots above were all shot at 1/8000th of a second at F45 through a proper filter. Notice how the disc of the sun appears dimmer as the moon covers it. It doesn't get bright again in this series, since toward the end, it was very close to the horizon, and was shining through more air to get to me, acting like an additional filter. The sun set before the moon completely uncovered it. This series covers about 90 minutes, while the entire event took about two hours.

By the way, if you have been looking at MSNBC this past week, you may have noted that they have been calling it an "annual" eclipse on their front page the entire time. It is NOT an annual event; they are relatively rare. It's one thing to be a copy writer and make the mistake, although I have no idea why someone with no astronomy knowledge would be asked to WRITE that article. But it's inexcusable for no editor with understanding of the subject to have ever seen the article. Even worse to leave it up for a week, in the face for the flood of complaints. Nice one, NBC. What else are you telling us that's just as ill-informed?

If you were outside looking at the eclipse, or just outside at all, you may not have noticed much looking around. It certainly would not have looked like the light from the sun had fallen by 80% or more. The picture at left was shot at ISO 100, 1/60th of a second at F10, just about ten minutes into the event. That would be when the first image in the composite was taken.




This was taken about an hour later, at the peak of the event, with the exact same exposure. Our eyes will accommodate the different light level, but people are often surprised to see just how much our eye will adjust. To most people, it looked exactly the same when both shots were taken.
If the effect is familiar, it's because low-budget TV and movie producers use the same trick to simulate "night" shots made in broad daylight, with a neutral density filter.



There were news articles about how solar filters were sold out at at every shop that carried them; that is great news, since it shows some interest. But there are other ways to look at the sun without ruining your eyeballs.

My daughter is showing a very simple solar projector here. It has the advantage over looking through a filter or welding mask in that it will even show sunspots, which makes it interesting anytime at all. Try drawing a sketch of what you see if you do this, then look again a few hours later and the spots will have all moved. Many people make quite a hobby of tracking sunspots, and it can get addictive.

It goes without saying that you don't ever look at the sun. ESPECIALLY if you have a pair of binoculars around. Also, be very wary for onlookers who will see you looking at the sun and who may unwittingly grab the binoculars and try and take a look for themselves. Don't use the binocs for looking at anything ELSE, either-the eyepieces can potentially become very hot, and could even crack as a result. You don't want that near your face.

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