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Sunday, May 20, 2012

Making a simple 'Sun Gun' to view Solar Events

To safely view the sun during solar events, one can buy solar goggles, or use a #12 or higher strength welders lens(for short term viewing, about 30 seconds) but how can you share the experience with others? This can be done by a using a pin hole projector, which is okay, or by making a 'sun gun' projector, which is a little better and is safe for everyone.
These are relatively easy to make, and there are several types and styles to choose from. A solar eclipse safety page ( http://www.exploratorium.edu/eclipse/how2.html ) is a good source as is this site - http://transitofvenus.nl/wp/observing/six-ways-to-see-the-transit/ . Both have good ideas that anyone can use with simple tools and a little know-how. My style is a convergence of a few I found, and works well.
What you need: a 5 gallon bucket, a small monocular (I used a scope off my old Daisy air rifle) a tripod or stand to support the 'sun gun' a back board and some bright white paper or card stock. Some duct-tape or bungee cords to hold it to the stand.
First, measure the diameter of the monocular or scope, the end opposite of the eye piece. Drill a hole of that diameter in the center of your bucket. I was able to use my mounting brackets for the air rifle to hold my scope in place, but you can duct tape yours in place through the hole. You can adjust the focus on the eye piece now or later, just DO NOT look at the sun through it while doing so, you can blind yourself that way.
After securing your bucket to your stand, you can use the wire handle and some small bungee cords to adjust and hold the proper angle. I placed a small hose clamp on my stand post and another through it to attach my bungee cords. You want to place your back board about a foot beyond the open end of your bucket to get a good projected image. My back board is a 1x10 shelving board that I taped a piece of white card stock on for better clarity. I used a scrap 2x4 for it's back rest. Now it's time for some aiming...
By using your back board, aim your sun gun at the sun, watch the shadows cast on the board, DO NOT look at the sun to aim. When your bucket shadow is nice and round, the sides cannot be seen you are almost certain to begin to see a bright dot, about an inch or so round, appear. That is the sun.
Now center your image into the shadow of your bucket. Now you can adjust your back board and or your eye piece for the best clarity safely by watching the projected image on the back board.
Now sit back and enjoy your solar event. This can be used to watch eclipses, transits of Venus or Mars, or just to watch the clouds float across the sun. (This last photo was taken with light cloud cover so it does not appear as bright when the sky is clear.)
One last note: DO NOT LEAVE YOUR SUN GUN UNATTENDED!!!! Focused light can begin to burn your back board and it can damage your lenses on your scope or monocular. Take a few frequent breaks and either cover your lens or move it as to not be aimed at the sun to avoid damage to the equipment.
I hope you enjoy many solar events o come!!!

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