Wednesday, November 14, 2012

PhotoProject :: Stay at Home Eclipse

The total eclipse this morning saw a hoard of photographers heading for Cairns and Port Douglas. Although I would have liked to be with them I was committed to being in Melbourne, which only got a partial eclipse. However this was an opportunity to expand on the telescope image projection technique, I have used back during the Transit of Venus Project in June this year. The method involves using a conventional telescope to focus the image of the sun projected onto a screen behind it. It worked particularly well to capture the partial eclipse, see sequences of images above, which I’m sure would have gone undetected by most in Melbourne despite the cloudless conditions.

As anyone with a decent telescope will know the tricky part is finding the object you want to observe. Under any decent magnification, the sky is a huge place. This is made even trickier because you must never look at the sun directly at any time and especially not through a telescope, so using the small siting scope is out. Then I had a brilliant realization, a bit like in the movie “The Dish”" when they were trying to locate the tiny Apollo 11 in the vastness of space!! (I won’t spoil the plot if you haven’t seen the movie yet, it is worth it). Well I realized I just needed to orient the shadow of the telescope so the barrel just became a circle and was thus pointing directly at the sun. All too easy and no looking directly at the sun required! A few minor tweaks where still required to ensure the projected image of the moving sun stayed roughly on the screen.
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