Manufacturer: Baader
Product number: SofiA4v

EUR 32,00

incl. 19 % VAT (DE)  
The VAT indicated refers to that applicable in Germany. After logging in, the VAT amount is adjusted to the applicable VAT of the stored delivery country. Therefore, the final price may vary accordingly.
excl. 6.95 € shipping costs (DE)  
Please log in to calculate shipping costs to your country.
more details to the shipping costs ...

  • On stock

rating: 5.0 of 5
  • Details..
  • Technical data..
  • In the box..
  • Reviews..
A good base for self-built solar filters:

With the Baader Astro Solar film, you can watch and capture the sun with full contrast. It offers also better protection against UV rays than simple glass filters.

With the attached manual, everyone can build his/her own filter for the astronomical telescope within minutes.

Note: If the lower resolution does not bother you, you can also equip telescopes with a solar filter whose aperture is larger than the filter film by making the inner circles correspondingly small during the self-assembly according to the instructions.

The Baader Astro Solar Foil has been awarded as the astro product of the decade in the USA.

The following characteristics have made this possible:
Optimal protection: The foil is covered on both sides with a filter layer, not only on one side. Every layer can contain micro-holes that bypass UV rays. With a layer on both sides, this is not possible any more.
Exceptional optical quality: The Astro Solar foil as an optical performance that is superior to e.g. Mylar foils. This is proven by an independent test. Compared with glass filters, the Baader foil is superior, too - in every section, it has a diffraction-limited performance. What is more, the foils is colour neutral. It does not give a green or yellow colour.
Very tough: A glass filter may break and a foil may rip. But the Baader Astro Solar Foil is, because of its special molecular structure, extremely tear-rigid.

The colour of the sun through the foil

The sun is depicted in a neutral cool white tone. It is a tale that the sun would appear in blue. The neutral tone allows views full of contrast and is described by many observers as "very pleasant". Especially at higher magnifications, this allows successful observations.

Some astronomers prefer a warm orange or yellow colur. This colour does not represent the reality and is - from our point of view - not optimal for maximum contrast and finest details, but in combination with this neutral-colour foil, one can experiment with differnt colour filters and can choose the best. Thus you are not fixed to one colour.

An example for photographic use:

This group was captured with the Baader Foil (photographical version) and a Baader Solar Continuum filter. Instrument: TS 127/1200mm achromatic refractor.

Such high-resolution pictures are only possible with a good objective and a good solar filter. There are many pictures like this that have been made with the Baader Astro Solar foil.
Transmission:approx. 1/100,000
Substrate:special film, developed for scientific use
Optical quality:diffraction limited
Safety:proven by the PTB, Braunschweig, Germany
Size:200 mm x 290 mm sheet
1 sheet (20 cm x 29 cm) AstroSolar, visual type
Plastic foil package + protective bag, with manual

Images from a comparative test

Interferometrical Test

Ideal picture - Strehl 1.01
(only theoretical)

Baader AstroSolar
close to the optimum -
like a good objective

Mylar Solar foil
irregularities are obvious. This would be
neither a good filter nor a good objective

Star test

Airy disc - 99.9% Strehl
(only theoretical)

Baader AstroSolar
94,1% inside the Airy disc
Comparable with a very good objective

simple mylar solar filter
57,2% inside the Airy disc
not diffraction limited any more

Recommended accessories


Written by Hartmut Colberg
on 2023-06-30

"Perfekt zur Sonnen Beobachtung "

Written by Peter Schmidt
on 2023-04-17

"Mit geringem Aufwand kann man sich ein Sonnenfilter günstig selber herstellen."

Written by Mathias Reinhard
on 2021-06-23

"Zur Herstellung eines Sonnenfilters ist die Folie echt prima. Man sollte zwar vorsichtig damit basteln, sie ist sehr dünn. Aber mit der beigefügten ausführlichen Beschreibung gelingt es jedem, sich einen sicheren Sonnenfilter zu bauen. "

Written by Michael Danielides
on 2021-06-02

"Die Sonnenfilterfolie verwende ich für meine 3D gedruckten Objektiv Filterhalter. Sie lässt sich gut verarbeiten und die Abbildung der Sonne ist ordentlich. Es ist aber klar, dass die Folie nicht an die Qualität eines Glasfilters reicht. Dafür ist sie etwas unempfindlicher als dieser."

Written by Miroslav Piencak
on 2020-10-16

"I enjoy it, it is nice addition to my scope experience."

Written by Jürgen Wimmer
on 2018-04-08

"einwandfreies, günstiges Produkt"

Written by Patrick Cambier
on 2017-08-30

"Good product"

Written by Thomas Klassen
on 2016-06-10

"die Sonnenfilterfolie tut, was sie soll. Was kann ich sonst dazu schreben?"

Written by Josef Dujak
on 2016-05-27

"Leicht zu verarbeiten und gut verpackt. Der Sonnenschutzfilter ist schnell gebastelt."

Written by Wolfgang Bodenmüller
on 2016-05-20

"alles ok"

Written by Detlev Scheiner
on 2016-05-04

"Ich habe die Folie benutzt um einen Sonnenfilter für mein 6"" f/5 Newton Teleskop zu bauen (volle Öffnung). Ich mag die neutrale Graufärbung des Lichts durch diese Folie. Erste Tests bei ca 100x zeigen mehr Details an Sonnenflecken als mit gleicher Folie am 3"" f/8 Newton. Der Merkustransit kann kommen."

Written by Thomas Bauer
on 2016-02-14

"bewährt und sehr gut"

Written by Eric ORVAIN
on 2016-02-09

"parfait pour fabriquer un filtre solaire pour objectif. Ce qui serait sympa, c´est de fournir un petit tutoriel pour construire ce filtre (entre deux cartons par exemple)"

Written by Yue Chui
on 2016-02-03

"I bought this not to build solar filters, but to create an observing window where I can directly look at the Sun whether unaided eye or through binoculars. I mount this sizeable film on to a large piece of hard card board. One can treat this as a portable solar observing window. The strong reflection means the lower grade Thousand Oaks black polymer solar film may be a better option for this purpose. Still, the quality of the Baader solar film is superb. For those who dislike the neutral white solar image, one can see a more pleasing yellow Sun by waiting until mid or late afternoon when the Sun is moving towards the horizon."