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Home Made Solar Filter

Posted: Tue May 10, 2016 6:53 pm
by pferland
So I made myself a Solar Filter for my telescope.

I didn't take any pictures during the process besides when the cardboard was all put together and after I was finished with my final design.

But, I started with some 2mil Double sided silver reflecting mylar. A single sheet of the mylar was not enough to view even with my eyes, so I next tried two which was better, but then with three it was perfect. I then used my small crappy broken 7x50 binoculars with the three layers of mylar and it looked good, so I moved forward with the plan.

I started with wanting to make a filter for the 25x100 Celestron Binoculars. I found that the plastic cover for CD/DVD spindles was wider than the opening of the single tube on the binoculars. I cut about 1.5inches of the plastic spindle off and cut it so i could then glue the two ends together and make the diameter match the binoculars only a little wider to fit the three layers of mylar. After the glue on the plastic ring ends dried I attempted to fit the ring over the mylar on one of the tubes of the binoculars. That didn't work out too well as the mylar just would not sit right with the ring around them it just buckled too much and generally looked really bad and didn't allow for easy application or easy removal or reuse, the mylar got all scratched up and made it look even worse.

That is when I decided to use the telescope for the next attempt, but with cardboard as the base for it. I took one of the bazillion boxes that we have stacked up and took the largest part and put it over the tube. Used a marker to trace the outside of the tube for a line to cut on. I left about the width of the cardboard from the inside of the marker line. This was so after I cut out the circle, I had space for the cardboard rim that will go around the edge to hold the cover onto the tube. I just cut strips of cardboard for the cover rim and taped them on from the top onto the rim from the outside. Little strips of packing tape going around the edge. I had to use two strips of cardboard, so where I had to make a joint, I taped the inside also to give it a little more strength. Once the rim was on I cut out the opening for the mylar to let a little light through. I think I did about an ince away from the edge to give it some strength and have a nice enough opening. I also built a second cover to go over the first one to make the aperture smaller if the larger one turned out to let too much light in on the 130mm mirror.

I ended up not needing it as the "full" aperture actually let just the right amount of light in to see everything.
The two filter apertures without the filter.
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Smaller aperture fit onto the larger one. I ended up not liking the gap between the two of them and cut down the rim of the small aperture one.
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Full aperture fit to the telescope and pointed at the sun.
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Closer view of the full aperture fit to the telescope and pointed at the sun. I ended up not needing the small aperture frame as it didnt let enough light in with three filters and two was not an option.

I even removed my spotter scope so that it wouldn't ignite me on fire since I didn't make a filter for that.
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Home Made Solar Filter

Posted: Sat May 14, 2016 10:22 am
by arizonajon
Good idea about the spotter scope. :shock:

In the garage, I have some magnifier glasses I wear when working on small stuff, and push them up above my eyes when I don't need them. Then I walk over to the truck, or whatever, out in the sun, and realize that I might burn holes in my head if not careful...

Cheers - Jon N7UV

Home Made Solar Filter

Posted: Sat May 14, 2016 12:15 pm
by pferland
Would look like you are growing horns out of your head lol.

I ended up making two solar filters for the 25x100 binoculars also.

I used the same construction method that I used for the 130mm telescope, but scaled them down to the size of the binoculars.

Both filters top side.
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Both filters, one upside down to show the opening.
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Side view of both filters
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Camera that I got for the telescope. The ZWO ASI120MM. I read some good reviews on this camera and it was a decent price. I went with the Monochrome camera because I want to use filters with it. I guess I could have gone with a color camera, but I wanted the B&W one first.
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I was up late on Wednesday night messing around with the camera. It took me a few minutes to figure out how it is supposed to be used :lol:

The camera gets attached to the eyepiece assembly that holds the eyepiece. I have only messed around with the 25mm so far. I hope the clouds say away tonight so I can try the 10mm.

Here are some of the crappy pictures that I took Wednesday night. The stars are just a dark spot in the northern sky that I could not see anything with the naked eye through the telescope. So I wanted to see what the camera was capable of.

All of the images are 1/2, 1, or 2 second exposures and I had to turn the gamma up also to see the faintest of them.
They are also all with the 25mm eyepiece on the 130x900mm telescope, so about 36x
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Then Mars showed up.
Was tricky getting a good focus on it and damn does mars move quick through the sky. Also had to lower the exposure time down to 1/500 and 1/1000 of a second as it was so bright compared to the dim stars.
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Home Made Solar Filter

Posted: Sat May 14, 2016 12:18 pm
by pferland
I forgot the images of the binoculars with the filters on them, and the layout of the camera and eyepiece setup.
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I need a better tripod for the Binoculars, they weigh in at 8lbs, and the tripod is really only rated to 8.5lbs.