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Making an inexpensive cell for BAADER
AstroSolar Film or TurboFilm optical-window. |
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| The film must be mounted flat and free of any tension -
Only this will provide first class optical properties. The quality of this patent
pending material is so high that any strain on the film will lead
to a very noticeable deterioration of optical quality (it is
preferable to have a few mild wrinkles than to place the film under
stress from pulling it). |
When mounted carefully, AstroSolar™ and TurboFilm™ can reach the quality levels of truly
precision polished glass plates (not to be compared with the
commonly available glass filters made of ordinary window glass w/o
ever having seen a polishing machine). |
| The "Cylinder" |
| At first you have to produce a cylinder of cardboard, to exactly
match the outer circumference of your Telescope tube or dew cap. In order to
achieve this, cut a whole number of cardboard layers, approx. 5 -6cm (2 inches)
wide. Wrap one piece of cardboard around your dew cap or lens cell and glue one
end onto the other. |
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| Fasten a second and third (and so on) layer of cardboard in
the same manner, until you have manufactured a stiff roll of cardboard, approx.
4 - 5mm (3/16") thick. Watch out that the finished "cylinder" will slide snuggly over
the tube and that it will be easy to slide it on and off the telescope.
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Hint: For telescopes with smaller aperture
one could try to find an appropriate "poster tube" and cut off a piece of
approx. 5 - 6cm length. Variations in diameter can be
compensated for by using
adhesive felt liner or by gluing Cork pads into the paper tube.
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| The "Window Cell" |
| Cut out two rings of cardboard (each
having 1 - 2mm thickness). The outer diameter of the ring - shaped
cardboard should match the outer diameter of your fabricated
"cylinder". The inner diameter should correspond to the actual
aperture of the instrument. |
After having prepared two such rings, both should be equipped on
adjacent sides with a large number of small cutouts of double tape along the
outer circumference of both rings. Now comes the tricky part - how to get the
AstroSolar or TurboFilm onto the taped ring w/o wrinkles or ripples. The film must not be
scratched - so put one sheet only of Kleenex (or other soft tissue) onto a flat
table. Tape the Kleenex onto the table so that this part is stretched out
evenly and cannot move on you. Only now put a square piece of film - (precut
to the size of the cardboard-rings) onto the piece of soft tissue. Do not tape
the film and do not stretch it! Just let it rest relaxed and flat on the
Kleenex. |
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Now take the first cardboard ring and lower it straight down onto the
film until every double tape clipping made contact with the film. Turn this
package around, tape the other ring onto the opposite side and cut away the
overleaf. Now your AstroSolar or TurboFilm TM should be mounted free from strain and
wrinkles between the two cardboard rings. Finally glue this "window holder"
onto the prefabricated "Cylinder". Now your "Do it Yourself"
precision Solar Filter or Optical Window is ready.
Enjoy it - you just saved about $100 - for the filter cell alone.
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When covering a larger Newtonian or Cassegrain Telescope for
Planetary Observation, you may want to also try an "off axis filter
cell". The reduced aperture may enable your large telescope
to perform to the level of a good refractor (by eliminating the
central obstruction and effects of turbulence on the larger
aperture). Or. for maximum resolution, a full axis filter can
be made from our new Maximum sized AstroSolar (46" x 46").
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