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29
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Pinholes smaller than 0.5 mm in size do not constitute a safety
problem since each such pinhole works as a minute "camera
obscura" - producing a real image of the solar disk - although of
extremely low resolution - given the ever so tiny "aperture".
Several such "solar ghost images" then do overlap to brighten
the background of the real solar image created by the telescope
optics.
Over time many such pinholes would noticeably deteriorate the
contrast visible in the solar surface details. For this reason it is
recommended to blacken larger pinholes (see instructions
below). In the effect that ever more, even tinier pinholes (of just
0.1 mm in diameter and smaller) will noticeably brighten the
image then it might be a good time to exchange the film in the
cell with the help of the same procedures as described in great
detail on
www.astrosolar.com
for DIY-production of filter cells.
Tiny pinpoint sized bright spots can be blackened on the inside
of the Solar Filter (the side facing the telescope) by applying a
tiny black spot, using a black felt marker or soot filled black
paint. Apply with small retouching brush. Considering the total
optical surface area, such small black spots do not have any
adverse effect on optical quality. Rather you will notice an
increase in contrast within finest solar surface details.
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B.1 Folds, Ripples, Creases
Any of the film patterns shown below are remains of the entirely
stress free production processes that AstroSolar
®
has to
undergo. Trying to avoid such surface textures inevitably leads
to gross astigmatism and noticeable loss of image sharpness.
In fact these patterns do not influence the quality of the image
at all. Do not let yourself be mislead by looking for the
cosmetics instead of the optical outcome.
B.2 Pinholes
Before each use carefully inspect your filter for mechanical
damages, broad scratches, streaks, extensive wipe marks and
other quality degrading influences
:
AS
T
F / AS
S
F / AS
B
F (AstroSolar
®
Safety Film 5.0):
by holding it very briefly at arms length towards the Sun.
B
D
SF (AstroSolar
®
Photo Film 3.8):
By holding it at arms length towards a bright LED or Halogen
lamp
