Equipment: filters

Telescope and Eye-pieces SkyWindow and Binoculars filters accessories

Baader Astro Solar Safety Film (Solar filter)

For observing the Sun, I use a homemade solar filter, constructed from Baader Astro Solar Safety Film, a high-strength polymer. It comes in different sizes and is offered at very reasonable prices. You can make a solar filter out of it yourself.

This is how I constructed mine:

Do not observe the Sun without using the proper filters. Looking at the Sun directly will severely damage your eyes!

  • First I took two sheets of heavy weight paper (size A4) and with a compass I drew a circle of 6 inches on the two sheets; I then cut out the circles; After that I cut the solar film to a size, just a little smaller than the paper sheets. Then I glued the two sheets together, with the solar film in between them;
  • Now I had to find something that fitted over the aperture of my telescope, and on which I could attach the two sheets of paper with the solar film; I used a nine-inch spring form (I don’t think my wife was very happy with me when she found out) and it worked out fine. I just used the outer ring of the baking form. I glued the two sheets of paper (with the solar film in between) onto the ring of the spring form;
  • Finally I glued three pieces of foam rubber into the inside of the ring; this way I can slide the home-made solar filter over the full aperture of the telescope, without damaging the telescope tube.

My solar filter, ready to use:

Baader Solar Filter
Baader Solar Filter

Of course there are other (and probably much easier) ways to construct your own solar filter. Use your imagination!

Folow this link to the BAADER site if you are interested in a manual on “Constructing a Solar Filter for Binoculars with Baader Astro Solar Film” (downloadable as a PDF file) or if you want to know how to make an inexpensive filter cell for Baader Astro Solar Safety Film. For technical details on the Solar Safety Film click here.

The Baader Astro Solar Safety Film provides good quality views of the Sun, without the risk of damaging your eyes. The image of the Sun through the filter is white with a blue-tinge. Sometimes I add a yellow filter, which threads into the eyepiece, to enhance the contrast (or just for the looks). I recently bought the Baader Contrast Booster. Baader claims that this filter, when combined with the Baader Astro Solar Safety Film will give you even better images of the Sun. I did not have the chance to test this yet. As soon as I got some observing results, I will report them in the filter section.

Here you can see the result of my homemade Solar filter mounted on my TAL200K telescope.

Using the Baader Astro Solar Safety Film, you can observe sunspots, Mercury and Venus transits, solar eclipses, faculae and the Sun’s granular structure.
Faculae are bright and glowing, cloudlike features which can be easily seen in white light.

Baader solar filter mounted on TAL200K

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