K3's AstroPhotography
"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4

Homemade solar filter made from Baader AstroSolar™ foil

Baader planetarium offers very good material for making solar filter - AstroSolar™ foil. It can be bought e.g. from Teleskop-Service company in Germany.

Here there is a description how I made solar filter by myself. I hope you may find it useful.
The leading idea is to have a standalone filter ring (with AstroSolar foil) and standalone filter body. The filter body then can hold another type of filters and it is also possible to stack more filters (it can hold, for instance Hartman mask).
Unfortunately, I haven't took pictures of my work from a beginning :-(, so I try to describe it by words...

1. I cut a 6cm wide carton stripe. The length depends on diameter of scope tube and should be a little bit longer. Then I prepared a stripe from black mat wallpaper of the same size for covering the inner part of filter body. 2. Then I wound the wallpaper stripe around scope tube and trimmed its length to proper size. Remember, the filter body must fit to scope tube with some clearance. Then I sticked the carton on wallpaper. To avoid snagging and unsticking of wallpaper during using filter I sticked the carton on wallpaper with some shift - the ends of wallpaper were on oposite side to ends of carton.

Uf, it was hard to me to explain it in English. I hope you understand...

3. I prepared a sticky tape (5cm width) - the type which must be wet before sticking. This type of tape we used to use as boys for creating rocket models body. With help of my wife I started to wind the tape around the carton stripe - until the thickness of filter body was about 4-5mm. Then I kept the body to get dry (several hours) - I left the body on scope tube, to avoid filter body shape deformations during getting dry.
After getting dry I cut the borders of carton (carton was 6 cm, while sticky tape was 5 cm wide).
4, Then I prepared a ring from carton - the outer diameter must be the same as outer diameter of filter body and inner diameter was 85mm in my case (the objective lens is 80mm). It causes some vignetting, because the filter is at the end of dew shield, but I couldn't afford larger inner diameter, because the width of the filter ring would be too small. My filter ring must have inner diameter 85mm and outer 101mm. Anyway, the vigneting will not be visible, because with this filter I can observe only Sun (angular diameter ~0.5°).
I sticked the black wallpaper on the inner side of ring (which will be sticked on filter body).

5, The carton ring prepared in step 4 I sticked on filter's body. The picture shows the front side of filter body.

6, This is view to inner part of filter body.

7, The next task was to create filter rings, which must hold AstroSolar foil. I chose CD cover plastic as a material for the ring. It is more solid than carton and is quite slim

8, I sticked the black wallpaper on the outer sides of the rings.
Later I put double sided sticky tape to inner sides of rings - they will hold AstroSolar foil.

9, Then I prepared AstroSolar foil. I put it on soft material (used for packaging audio/video electronics). Then I drew the outer diameter of filter ring.

10. For better manipulation I sticked the foil to carton. It enables to keep it flat.
Then I sticked the foil to one of filter rings (remember double sided sticky tape in step 8).
Note: The foil has silver color, but some reflections caused that it looks like brown on photograph.

11. I cut the borders of foil (the carton was automatically removed, because it was sticked on its borders) and then I sticked the second ring. The result is nice solar filter.

12, Then it was time to finish filter body. My wife created a cylinder jacket from carton and put it on filter body. Then she sticked the black wallpaper to outer part of filter body.

13. The filter body is ready for use

14, The first light for testing came through the solar filter from our halogen reading-lamp

15, Finally, here is my solar observation setup...

16, ... and detailed view of solar filter

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Last Update: 03.05.2003