Jump to content

2052839955_Mobilephonebanner.jpg.a502a319d7033354d442937f2edd0c2c.jpg

DIY White Light Solar Filter for 8” Dob


PeterStudz
 Share

Recommended Posts

Having purchased a ready made solar white light filter for my 4.5” Newtonian last year and enjoyed observing the sun, I decided I’d like something similar for my Skywatcher Skyliner 200p Dob. At the time I was new to all of this and didn’t feel confident with making my own.

This started life as round paper mache box from Hobby Craft for £5. I’m lucky to have a Hobby Craft close to me. It’s a wonderful shop…

https://www.hobbycraft.co.uk/search/?q=round box paper mache

And a 20x29.5cm sheet of Baader AstroSolar Safety Film from FLO for £22, although I see that it’s now £25. This sheet doesn’t quite cover the full aperture (you need some to stick down at the sides) but it’s large enough…

https://www.firstlightoptics.com/solar-filters/baader-astrosolar-safety-film-nd-50.html

I made sure that I followed the instructions that came with the film. Eg the use of double sided sticky tape to hold the film down and not fitting the film tight.

I had thought that the 25cm box would be ideal for my 8” Dob. But I didn’t realise that the size was the outer dimension of the lid and not the internal diameter. It was a really snug fit. Now you could get away with this, and it might actually be easier, but I had a design sketched out which needed a bit of a gap for some tabs. So, I used the box lid and made it longer by sticking a couple of strips of veneer (which I already had) into the inner part of the lid. With some 2mm black craft foam this was now a tight fit on the end of the OTA. I’m not keen on relying on a tight fit so for security I put some holes in the tabs which fit over the adjustment knobs of the secondary spider. The foam tabs being stuck down with Evo-Stik impact adhesive.

A circular hole of 185mm diameter (as much as I could get away with) was cut using a sharp knife into the box lid. This was painted white on the outside with black trim. 

I then made a cell with another piece of card, added some card tabs or “ears” so that when I dropped the cell into the lid it would be an accurate fit. For me gluing “ears” is far easier than trying to cut the whole thing to an accurate fit. This was painted with blackboard paint on one side with double sided sticky tape on the other. 

The film was carefully stuck to the tape on the black card cell. Following instructions and ensuring that the film wasn’t tight. More double sided tape was added to the round box lid and the cell plus film dropped and stuck down. I then finished off by adding flocking material to the inner sides which were scraps left over from flocking the OTA. Blackboard paint would work just as well but I didn’t want to risk dropping any onto the film. 

That’s it. I’ve used it a few times now and it seems to work well. It’s certainly not going to fall off.

As I mentioned before - you could get away with cutting down the box rather than using the box lid. And a cut down box will make a tight fitting rear dust cover as shown in the pictures (shown unpainted).

And every solar filter needs a safe storage box. I made one out of a lager 29cm Hobby Craft box, painted and decorated.

D68E1AD4-BA51-4B57-8A17-4715FC7DA59C.jpeg

3FD60208-9D52-49A3-B8B5-90AEF0E126A4.jpeg

E8CE0D1C-3945-4EDB-90E9-0B8E77067A98.jpeg

913381F2-979D-495A-8DF6-7E55B041FCDE.jpeg

183750D2-17A6-47AF-A2FC-D5D530F78B28.jpeg

13826621-5331-4DB4-AE02-25EC43C092CE.jpeg

AC87CB3C-D6BC-4A4B-AFC5-621E5AF277F7.jpeg

4864F66B-3443-4E9C-B5A5-0665513E8B24.jpeg

D3E7CA5D-A178-4C94-9290-1B6586CD2207.jpeg

CC3DA455-52B9-4442-B8E0-CDE8A50DAC6A.jpeg

3017A98D-1056-4463-86F4-36E7B076FF1E.jpeg

96C2E4F9-2A10-45A5-93A3-885C76903E74.jpeg

91D93621-EBFE-44E1-8072-6AF5A2C2F958.jpeg

C8FB3D02-0E2E-4E8F-84AD-998D8E949E74.jpeg

  • Like 6
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.