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How to make a solar filter for an 8" dob?

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#1 maxwolfie


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Posted 11 January 2013 - 04:34 AM

Hi all,

I recently bought some Baader solar filter sheet and I was hoping to be able to make a simple/easy solar filter out of it this weekend. I have an 8" dob and the filter that I bought is probably not quite that wide - It's an A4 sheet so I'd say it's good for 6" (at least) or up to 7".

What the easiest/safest/cheapest way to do so?

#2 bob71741



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Posted 11 January 2013 - 07:55 AM

There are many ways to make a filter for your DOB, and they may be found by searching on this forum or others; but, if you want a quick and dirty way, I suggest the one that I made for my DOB.
You may need to find a way to securely attach it to your DOB. In my case, the rim of the tube was pronounced enough that once the serrated cut edge of the filter was forced onto the tube, gusts of wind could not blow it off; you may need tape for yours.

see attached images.

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#3 bob71741



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Posted 11 January 2013 - 07:56 AM

back view; note serrated edge on cutout.

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#4 JeanB



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Posted 11 January 2013 - 03:18 PM

Interesting way to do it. Far simpler than the one I made. With that you will be able to priority mail us your image!

Thanks for posting Bob!


#5 maxwolfie


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Posted 12 January 2013 - 12:16 AM

So, if I have an 8" dob, should I make an off-axis one? Or, should I be leaving 7"? all around equally, or 6" or what? Some guides advise that it is better to have a smaller aperture rather than a larger one.

#6 marktownley



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Posted 12 January 2013 - 05:11 AM

Hmmm, I'd go full aperture I think.

#7 George9



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Posted 12 January 2013 - 04:19 PM

I have a 10" full aperture Baader solar film filter for my dob, and I love it. During rare moments of perfect seeing (perhaps once per year) I can see very fine details in a sun spot. The penumbra has a detailed zebra effect and the umbra shows detail. Granules, pores, and faculae are great. Even with bad seeing, the view is nice and I don't regret the full aperture.

It's made of cardboard and secures to the scope with Velcro.

Since you are stuck with 6 or 7 inches of film, I would leave it as big as possible and center it.


#8 Gary BEAL


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Posted 12 January 2013 - 04:58 PM

Depends on your abilities, and your ambitions of course.
I have built them from rings of cardboard or plastic pipe fittings in the past.
Recently I built up one for my newt, it uses a dob base, or can be mounted on the NEQ6. As most will tell you, something this big needs a decent dose of seeing, but when it does come together.............

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#9 Jeffrey C.

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Posted 13 January 2013 - 04:35 AM

I would also go for a full aperture filter.

#10 NeilMac



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Posted 13 January 2013 - 06:05 PM

Is their a supplier in Canada anybody know?
Been looking , so far the only place for sheets is in Germany and the shipping is allot more then the product :(


Scratch that !
Canadian telescopes does carry it, didnt show up on their search but found it by Internet search lol.

#11 Jim Rosenstock

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Posted 14 January 2013 - 09:55 AM

I would also go for a full aperture filter.

Absolutely. It's simple to make an off-axis mask, to turn your full aperture filter into an off-axis model. You don't need a second filter, just a piece of cardboard, scissors, and 3 pieces of tape...

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