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DIY Solar Film Cell - Any Examples To Share?

solar DIY
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#1 gfstallin



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Posted 15 October 2019 - 12:01 PM

Hello folks, 


I'm thinking of buying some Baader solar film to make white light solar filters for my scopes. I'm looking for ideas on how to craft a cell to hold the filter material and mate it to the telescope. I've seen instructions from Baader and they seem mostly simple enough. I'd be curious to see what folks have come up with (even if they followed the Baader example). If you have any pics of your DIY filter cells and information on how you built them, I'd love to see what you did. 


Moderators, if there is a more appropriate category for this post, please don't hesitate to move as you see fit. 





Edited by gfstallin, 15 October 2019 - 01:52 PM.

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#2 vtornado



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Posted 15 October 2019 - 12:29 PM

I have not built my own, but because I have bought a different sized scope, I either have to find

a new filter or build my own. 


Here are some thoughts.


If you make it out of cardboard as per the instructions, you can brush on some thompson's water seal

or similar product.  If stiffens up the cardboard, and makes it moisture resistant.  I made an aperture mask like

this and it is a similar concept.


I have built some astro stuff out of coragated plastic, which is available at michaels.

Cuts with scissors or exacto knife, but stiffer than paper.


I am afraid of a gust of wind blowing my filter off.  With my old filter I actually taped the filter

onto to the OTA.  I don't think a homemade filter is any more likely to blow off than a commercial one,

(maybe less likely) but you may want to make it strong enough to be taped onto the OTA. 

If it is generally windy, the sky is generally turbulent, and I don't observe, however, you never know

about a rogue gust.

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#3 havasman


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Posted 15 October 2019 - 03:26 PM

Here's mine for AT115EDT. Local craft store provided needlepoint hoop for base, needlepoint fabric, posterboard, black foam sheet. I had glues, tapes, Velcro pads and black acrylic paint. Bought 90mm square of Baader Astrosolar film from Agena. Hair, feathers, guts and all for < $30.


This is going to read like it was complicated but it was easy.


Solar Filter 1 - sm.JPG
That's it. Light tight w/o any leaks. Front piece larger diameter than main body to shade the scope tube. A Scopestuff.com solar shield (not pictured) shields the observer pretty well.


Solar Filter 2 - sm.JPG

This shows construction. The hoop's made to secure the fabric so I cut an oversize hole @ 90mm in the fabric, mounted it centered in the bore, torqued down the hoop's fasteners, painted the fabric thickly with acrylic to stiffen it, cut posterboard circle to match hoop O.D. with final aperture of @ 83mm and stuck that to the front surface of the doped fabric (the front surface of this ring is where the film mounts), cut wide strip of posterboard to make cylinder to slide over scope dew shield and glued it to inner bore of hoop, cut strip of black foam and glued it to inner bore of paper cylinder, mounted solar film FOLLOWING INSTRUCTIONS ON BAADER ASTROSOLAR FILM WEBPAGE, cut front piece from posterboard to match aperture and glued it in place w/o restricting film, used small Velcro tabs to get final fit of dew shield to inner bore and DONE!


Solar Filter 3 - sm.JPG

Here you can see the black foam makes a boss for the dew shield to seat against securely. And the Velcro discs are seen.


Solar Filter 4 - sm.JPG

Note the bumpers made from the foam that keep the box lids from contacting the Baader film and keep the filter and housing from bouncing around. Cardboard was added to the inner box walls nearer the bottom to match the housing O.D. for secure fit.


EDIT - It works very well and is about as safe as you'll likely find. I secure the filter housing to the dew shield with a piece of gaffers' tape for outreach events just for extra insurance against someone fiddling with it.

Edited by havasman, 15 October 2019 - 03:35 PM.

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#4 44ye


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Posted 16 October 2019 - 11:07 AM

Youtube link below many samples to choose from


https://www.youtube....ht solar filter

#5 JoeInMN


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Posted 18 October 2019 - 11:00 PM

Mine has a 60mm aperture. The Baader film is glued to the usual cardboard ring, trapped between a bit of PVC pipe and an end cap with a hole cut into it. A wrap of adhesive rubber weatherstrip gives it a snug fit jammed inside the dewshield of my Tasco 59T. It takes a good firm pull to get it out; no chance of it falling out accidentally. I originally intended for the cap to be facing outward (hence the do-not-touch warning), but found that it works a lot better the other way around. The orange part is a rubber band to discourage the ends of the weatherstrip from coming loose. My first try at a solar filter, but seems to work well. Too bad this transit probably will be the only thing to actually view with it for quite a while...



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