VERY IMPORTANT NOTE - PLEASE READ
If you want this item in time for the May
20 Eclipse, then please order well in time, especially if you plan to
use USPS First Class Mail (Standard Shipping). First Class Mail
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shipping location in CA. Please plan accordingly to avoid
This listing is for the sale of ONE
piece of Baader AstroSolar Filter Film (Square 5" x 5" Piece). Other
sizes are sold separately.
Use Baader's AstroSolar Safety Film to make cost effective
solar filters for your binoculars, telescopes, finders, or cameras. Get
ready for the Annular Solar Eclipse (May 20) or the Transit of Venus
(June 5). Film pieces are available in many sizes ranging from 1.5" to
20" to suit your observing needs.
- We do not accept any returns on Baader film. Please make sure that you order the right item and size for your needs.
A. Baader AstroSolar Safety Film - Brief Overview
In its September 2000 issue, Sky & Telescope magazine proclaimed
Baader Planetarium's AstroSolar™ Safety Film to be "the new standard in
solar filters." AstroSolar Safety Film delivers white light views of the
Sun that are unmatched by any other objective solar filter or material.
The views through AstroSolar display fine solar details, including
fine penumbral detail, solar granulation, and lighter colored faculae.
The disk is set against a dark background, free of the haze and scatter
that is common in typical 'mylar' films or inexpensive glass filters.
The performance of AstroSolar is even more remarkable when considering
its very low cost. When combined with Baader's tips for a simple
do-it-yourself filter mount (see below), anyone can construct a complete
low cost, high quality, white light solar filter for any telescope.
What is even more important - with AstroSolar Film the Sun appears in
its real color - neutral white (with only a slight bluish tinge). Other
films and glass filters produce a blurry bluish or
reddish/orange/yellow Solar image, thereby cutting part of the spectrum.
Especially with an orange sun, it is very hard to see faculae regions
which are visible predominantly in the blue wing of the spectrum.
Due to its neutral color balance, AstroSolar Film enables the use of
various color (or interference) filters which allows the observer to
concentrate on certain spectral passbands for investigations of
different layers within the solar "atmosphere". It is also possible to
further improve the stability and sharpness of the solar image through
the use of the Baader Solar Continuum Filter (sold separately). Views
of granulation and faculae are particularly enhanced through the use of
this continuum filter, in combination with AstroSolar film. Users of
achromatic refractors will be particularly pleased with the performance
using this additional filter.
Please note that you cannot see solar prominences with white light
solar filters such as this - that requires the use of sophisticated and
significantly more expensive narrowband solar filters or telescopes.
B. Information About our Pre-cut Square Film Pieces
offer Baader AstroSolar filter film in visual density, ND 5 (0.00001
transmission) for direct visual use only. This can also be used for
photography. We offer the film in available in many sizes at excellent
prices. All pieces are square and are shipped flat between two stiff
cardboard sheets, except full sheets (0.5m x 1m) which are shipped
rolled in a sturdy tube. We also provide a minimum 0.25" cutting
margin on all sides of the sheet. All pieces we cut from larger sheets
are handled very carefully and checked individually before shipping. We
take great care while handling the film and will not sell you a piece we
think isn't safe. Since 2003, we have literally sold thousands of
pieces to amateur astronomers and photographers worldwide.
C. Making Your Own Solar Filter
commercially made solar filters are available, either using Baader
AstroSolar or other film types, it is fairly easy and much cheaper to
make your own custom solar filter for your telescope or camera.
Instructions for making a simple solar filter cell are included with
the film piece you purchase (the instruction sheet can also be
downloaded from the link below). Baader AstroSolar film filters must be
mounted in the front of the telescope. A simple Google search for solar
filters will show you dozens of sites with examples of filters other
amateur astronomers have made, along with some excellent photos of the
Sun shot with this film.
You can construct a full aperture filter or a smaller off-axis filter
for your telescope. A full aperture filter has an advantage of more
light capture - nice, especially for long focal length telescopes (like
SCTs), but by no means necessary. However, full aperture filters are
also reputed to provide higher contrast, higher resolution (since you're
using a larger aperture, the theoretical resolving power is higher),
and are more comfortable to use (since you get a larger exit pupil) when
the conditions are good. On the flip side, a smaller aperture provides
steadier images when seeing conditions are turbulent, which is most
often the case in most places. In most case, an unobstructed aperture of
3-4 inches should be sufficient.
D. Appearance of Baader AstroSolar Film
first glance, Baader AstroSolar Film appear to be like ordinary aluminum
foil. You will often notice streaks or bends on the Baader film you
receive. Sometimes, it also appear that the film might be slightly
"warped." This is perfectly normal and natural and does not imply that
the filter film is defective or used. The optical and mechanical
properties of the film are not compromised. Please also note that the
"flashlight test" is not a good way of inspecting this film. Putting it
right against a very bright light will show a very mottled and
non-uniform appearance, but again, this is normal and does not indicate a
problem with the film piece.
E. Eye Safety
AstroSolar Film is essentially
free from pinholes, since - unlike even the most expensive glass filters
- it is coated on both sides, so that the chance of two pinholes
overlapping each other is extremely faint. Pinholes do appear, but to 1
out of 10000 only, in optical density 2.5! This is because pinholes act
as diffuse sources of light, not point sources. Baader AstroSola safety
film has been approved for eye safety by the National Bureau of
Standards in Germany, the PTB. Unlike any other Solar Filter on the
market, AstroSolar is CE-tested according to EG-Norm 89/686 and EN
169/92 (notified body 0196). All processes connected to this product
have been thoroughly tested. Coatings are inspected constantly for
consistency to ensure your eye safety!
F. Technical Specifications
- AstroSolar Safety Film is a specially manufactured streak- and blister-free foil only 0.012mm thick.
- The film is manufactured by Baader Planetarium, Germany.
- The base material is not Mylar. The quality of the solar image is
immeasurably better than can be achieved by using so-called Mylar
"rescue blankets" or similar materials.
- The basic development of this precision film was made in laboratories
for nuclear and particle physics. Due to its absolute homogeneity, the
foil attains the optical performance of high quality plane-parallel
- High density coatings on both sides of the foil ensure a highly
uniform filtering capacity without pinhole effect, resulting in an
extremely contrasty solar image with neutral density characteristics.
The Sun appears in its real color - neutral white - not blue or orange.
- The coating of AstroSolar Safety Film is subject to constant quality
control. Its reflective property (reduces intensity of sunlight by over
99.999%, i.e., by a factor of over 100,000 in the case of visual film)
and security for direct solar observation is tested repeatedly by the
PTB (German National Bureau of Standards for Eye Safety).
- One layer of this foil is sufficient for the construction of a safe, high resolution solar filter.
- AstroSolar film is available in two densities, ND5 (0.00001
transmission) for direct visual use, and ND3.8 (0.00016 transmission)
for photography only. We only stock ND5.
(Source: "Baader AstroSolar Safety Film" and "Original Baader
AstroSolar Safety Film" information sheets, distributed by Baader
Planetarium Astronomical Instruments, Germany)
G. Cleaning AstroSolar Film
We strongly recommend that you store your completed filter in a
container to protect it from dust and damage when you are not using it.
Similarly, protect any unused filter material so that it is in new
condition when you need it. Fingerprints on a metallized surface are to
be avoided under all circumstances. It has the same consequence as
putting fingerprints onto a telescope mirror.
Since your AstroSolar filter will be open to dirt and dust, the
coating may require cleaning after extended exposure. If the dust is
loose, you may be able to blow it off with compressed air or an airbulb,
both available in camera stores. Since the coating is harder than
regular aluminum coatings applied on mirror surfaces, it can be cleaned
with a solution of dishwater detergent and distilled water. Obtain
sterilized cotton wool (as used for eye application), available in
pharmacies. Normal cotton wool as used for cosmetic purposes should NOT
Use careful, gentle strokes. For each stroke, a new portion of cotton
is to be used, soaked with the cleaning solution. This helps to avoid
scratches in the metal surface due to dust grains picked up by the
Check the cleaning result by holding the cleaned filter up to the
Sun. If scratches or pinholes show up, exceeding a combined uncoated
area of 10 square mm, the film is regarded as unsafe and must be
destroyed. Tiny pinholes can be covered with a black felt-tip marker. If
the filter becomes very dirty, we encourage you to replace it, rather
than risk damage in the cleaning process.
H. Instructions on Making an Inexpensive Solar Filter Cell
• Making a Solar Filter Cell (Pdf file format, 241KB)
Note: Occasionally, the product you receive might have a slightly different cosmetic appearance or labeling than what is shown. This can often change from batch to batch according to the whims of the manufacturer. However, you will always receive a brand new, original product as described above.
Text and photos - Copyright Agena AstroProducts. Reproduction without permission prohibited.
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