August 21, 2017 is a red letter day for much of North America including Kentucky. On that date we will enjoy a total eclipse of the sun. In fact, one ofthe best locations to view the eclipse is in Hopkinsville, KY, less than an hours drive from Bowling Green. Bowling Green will be located right on the northern edge of the eclipse path and will be able to see the totality, but a few miles south and west will provide much better viewing.
Some of you out there are probably wondering about how to photograph this event without damaging your camera or your eyes. There are a number of commercially available filters you can buy that attach to your camera lens that will do a nice job, but they tend to be rather expensive. So, I'm going to show you how to build a Do It Yourself version of a solar filter that works quite well. It cancels out 99.999% of the light along with all the UV and other bad light and allows for direct viewing and photographing of the sun.
First of all, this version was made to fit my 50mm - 500mm Sigma Lens. The concepts shown here can be used to build a filter for any size of lens, its just a matter of scaling down the size of the main tube that is used to fit your lens. Also, use only solar filter material that is designed for solar viewing. Do Not compromise on this, your eyes will not appreciate the cheaper materials and they can be damaged.
Here is the parts list: 1 - 4 inch Cardboard shipping tube...about $6.00. (Use tube size that will fit your lens)
1 - 8x8 inch Black Polymer Solar Filter Sheet - about $18.00 (one sheet will make
several filters) Amazon Link is attached to bottom of this article
Some double stick tape
A small piece of thin cardboard
Step One: Cut a 5 inch section off the end of the shipping tube. Use a Hacksaw to make a smooth cut.
Step Two: Remove the plastic end piece and cut out the center of the cap leaving about 1/4 inch all the way around the edge along the bottom. In this case just follow the ridge that outlines the center of the plastic cap. This creates the hole through which the filter material will be applied.
Step Three: From the 8x8 inch sheet of black polymer filter material cut a square section large enough to cover the end piece. In this case about a 4x4 inch piece worked just fine. While cutting the filter leave the filter material inside its cardboard holder and cut across/thru the cardboard. Do not try to remove the filter material and cut it separately as it is too flimsy and awkward to cut that way.
Step Four: Take small strips of double stick tape and cover the bottom inside flat 1/4 inch wide portion of the end piece. After covering the end piece with tape, trim the tape so none of it extends over the cutout section. Tape should only be applied to the flat piece along the bottom.
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| Attach Polymer to bottom of the cut out plastic cap sealing along the double sided tape. |
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| Make sure the Silver side is facing forward. The end result should look like this. |
Step Five: Carefully place the Black Polymer material onto the back of the plastic cap. Be sure the shiny silver side is facing forward or looking thru the hole toward where the sun will be. The black side should end up on the inside of the tube. Gently, but firmly press the material onto the sticky tape and make sure it is sealed all the way around. It's okay if the material has some crinkled edges. It will not affect the performance. Try not to scratch the material though. Just make sure the entire bottom surface of the plastic cap is covered so that no light can penetrate through.
Step Six: Gently press the plastic cap back into the cardboard tube.
Step Seven: Depending on if the cardboard tube is larger in diameter than your lens, you may need to shim
up the inside of the tube for a tighter fit. To do so, simply cut another section of the tube, about 3 or 4 inches is enough, then cut a 3/4 inch slice out of it. Pinch the ends together and slide into
filter tube. Additional shimming can be applied once the filter is slipped over the end of the lens.
Just use a 3 or 4 inch piece of thin cardboard folded over so it can slip into the gap between the
lens and the filter holder.
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| Additional piece of tubing with a small slice cut out of it, pinched together and then inserted into the maintube. This provides a bit of shimming to create a tighter seal around the lens. |
Here is the finished product:
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| Notice the folded thin piece of cardboard wedged between the filter tube and the lens. This keeps the Filter tube tight so it does not wobble around or fall off. |
...and here is the results. Now its just a matter of having clear skies for the eclipse and/or some interesting sunspots to appear. Exposure on this one: Manually set f/8.0 1/500th sec ISO 100 500mm (cropped).
Amazon Link for filter material: https://www.amazon.com/Solar-Filter-Telescopes-Binoculars-Cameras/dp/B00DS7S52W/ref=sr_1_1?ie=UTF8&qid=1489027135&sr=8-1&keywords=mylar+solar+filter
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