Baader H-Beta Narrowband-Filter (5.5nm) – CMOS-optimized

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Baader H-Beta Narrowband-Filter (5.5nm) – CMOS-optimized

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€ 185.00 Price excl. German VAT tax (19%): € 155.46

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Which side should face the telescope?
  • Baader H-Beta Narrowband Filter – Precision Grade
  • 5.5 nm FWHM, recommended for optical systems from f/15 to f/1.8
  • Reflex-Blocker™ hard coated and planeoptically polished – with sealed coating edges (Life-Coat™)
  • Blackened edges all around, with filter-lead-side-indicator in the form of a telescope-sided black outer rim
  • Optimized for modern CMOS cameras, but likewise excellent for CCD camera technologies

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€ 185.00 Price excl. German VAT tax (19%): € 155.46

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What's the actual size of your 2" filters in "mm" with and without frame/ring? What step down adapter is suggested from a 52 mm to "-- mm"?
Question by: Waqas Ahmad on Oct 10, 2016 7:54:00 PM | 1 Answer(s)

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What are the threads and pitch of your 1.25" and 2" filters?
Question by: Anders G. on Sep 20, 2017 12:55:00 PM | 1 Answer(s)

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What is the actual dimensions of your 65mm x 65mm filters, for instance, the Baader RGB R-Filter 65x65mm – CMOS-optimized
Question by: R. Paulson on Jan 31, 2024 6:24:00 AM | 1 Answer(s)

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Baader H-Beta-Filter – the H-Alpha-Filter for visual observations!

The Baader H-Beta-Filter with 5.5nm halfband width is especially useful at telescopes with 8" or larger apertures or if you are working with large exit pupils. This narrowband-filter delivers a much higher contrast, compared to common visual H-beta-filters. H-Beta-nebule-filters with a wider half-width deliver a brighter image and will also show you e.g. the California nebula,but it won't be so clear, and you will miss many of its inner structures. Without any filter, this nebula (to name just one of many) will be completely invisible under brighter skies.

About Baader H-alpha Filters and why they aren't suited for visual observations

The development of narrow-band H-Alpha-filters soon proved to be a "Game-Changer" for Amateur-Astrophotographers. No other spectral line of emission nebulae will give you so much information for the creation of "pretty pictures" as this Hydrogen-line. This is supported by the better coatings, sensitive CCD-cameras, motorized focusers and last but not least the the incredible tracking precision of modern mounts, which allow for very long exposure times with very narrow-band filters. Modern images are often based on exposure times of 30 hours through the three common, very narrow-band nebula filters. But to make use of this, the mount must provide "subpixel"-tracking, the focuser must not flex even for a micron, and its motor must compensated for temperature changes by keeping the focus up to a fraction of a millimeter... All this is possible – but you need high-end equipment.

This is not necessary for visual observations. But unfortunately, we do not profit from those photographically wonderful filters when we are looking through the eyepiece – at low intensities at night, the human eye is almost blind for this part of the spectrum. During daylight, when there is plenty of light, we can easily see H-Alpha. But at night and low-light, we can't perceive these wavelengths. In contrast to a camera, our eyes also can't add upp the light.

Because of this, most visual observers use the well-known O III-filter. The human eye has got its highest sensitivity between 500nm and 520nm, where we can observe many structures in supernova-remnants, planetary nebulae and so on. But they are pretty useless for deep sky objects which shine mainly in H-alpha.

The alternative – Baader H-Beta filter for visual applications

For the H-alpha-objects mentioned above, the H-beta-line is a good option: At 486nm, it still quite close to the region of highest sensitivity of our eye. Because of quantum-mechanical coupling with H-Alpha, we can usually see the same structures. H-Beta-filters are much more efficient than O-III, because most nebulae emit hydrogen-light – although H-Beta is not as popular as H-Beta.

A H-beta filter can be regarded as a visual H-Alpha-filter.

The H-Beta-spectrum is indeed very interesting. Quantum-mechanics define a fixed ratio between H-Alpha and H-Beta, but because of the shorter wavelengths, H-Beta has got a higher energy. That's why H-Beta suffers from a higher extinction rate in interstellar dust regions, which can easily be detected. The ratio between H-Beta and H-Alpha gives you information about the amount of dust between us and the source, which is especially interesting for scientific work. For astrophotography, you can scale down the intensity of H-Alpha to simulate an H-Beta-filter – and if you are observing with your eyepiece, you will see structures which were almost invisible before.

Visual observers profit from the fact that a H-Beta-filter can show the dust regions in hydrogen-emitting nebulae quite clearly, similar to a photographical H-Alpha-filter. Larger telescope apertures can even show the split-up into two lines – and the soft phase-out towards the edge.

The filter is almost as impressive when you are looking at the dust tails of comets. Especially light with shorter wavelengths will be scattered more in the dust tail, so that the contrast to its surroundings increases. Light with even shorter wave-lengths will be scattered even more, but our eye is not so sensitive for these parts of the spectrum. The true dimensions of the sometimes very long dust tail may only be recognizable in the eyepiece with the help of a H-Beta-filter. The H-Beta line is also outside of the prominent lines of the gas tail, so the dust tail can be better deiscerned from the gas tail – and the contrast is increased even more.


A dielectric H-Beta-filter is no allround-filter like e.g. a Neodymium-Skyglow-filter. But it is the best available tool to see faint details, because you can visually see the dominating hydrogen emission lines in the sky – something which an O-III-filter can't show you. Together with an O-III-filter, it covers the most important spectral lines of emission nebulae and is an important tool for visual deep-sky-observers.

This new generation of Baader CMOS-filters features:

CMOS-optimized Baader Filters
  • Increased contrast
  • Ever more narrow passbands
  • Reflex-Blocker coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
  • FWHM on each filter category carefully designed to allow for 1:1:1 exposures, matched for typical CMOS quantum efficiency and s/n ratio
  • Identical filter thickness to existing standards, with utmost care for parfocality
  • Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
  • Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed, read more)
  • Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment

  • Further information, test reviews, image results...

    Don´t be misled.

    These all new CMOS-optimized filters work magnificently with all existing digital camera technologies, be it CMOS or CCD. However – an owner of CCD-camera-technology will still find our previous, extremely affordable, narrowband filter technology to be fully apt for excellent imaging. But: "the Better always is enemy to the Good".

    ... can be found on our detailed Blogpost:

    Baader Blogpost:
    New CMOS-optimized Baader Filters

    Baader Blogpost:
    A report on visual use of the Baader H-Beta 5.5nm CMOS filter

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    2 Item(s)

    Christoph Hay 41/02/2021 11/02/202112:38
    • Rating:
    Visuelle Nutzung des H-Beta 5.5nm CMOS Filters
    Im Sommer 2021 fragte ich bei Baader Planetarium nach, ob ich die neuen OIII CMOS Filter paarweise zwecks Erkundung ihrer visuellen Möglichkeiten in der Fernglasbeobachtung galaktischer Nebel ausleihen könnte und erhielt außerdem noch Prototypen des nun erhältlichen CMOS-optimierten H-Beta Narrowband Filters 5.5nm. Ich hatte – ich muss es gestehen – zunächst keine besonderen Erwartungen an diesem Filter. Ich wurde jedoch schnell eines Besseren belehrt.

    Seit meinen Versuchen mit den Filtern, welche ich in einem ausführlichen Blogpost der Firma Baader Planetarium habe zukommen lassen, konnte ich den enormen Gewinn des 5,5nm Filters in der visuellen Fernglas-Beobachtung ausgedehnter Nebel schon mehrfach am Kaliforniennebel sowie an weiteren Nebeln des Sommer- und Herbsthimmels bestätigt finden. Der Filter ist derart bahnbrechend, dass ich beide Filterpaare käuflich erwerben wollte, ja musste.

    Ich meine, dass dieser Filter für jeden engagierten Nebelbeobachter preiswert ist angesichts der neuen Türen, die er in der visuellen Beobachtung aufstößt.
    Wir freuen uns sehr, dass sich der neue CMOS-optimierte 5.5nm H-Beta Filter auch visuell derart bewährt. Den ausführlichen Testbericht von Herrn Hay mit Filtervergleichen und ausführlichen Beschreibungen finden Sie hier:
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    Andreas Bringmann 300/10/2021 28/10/202107:09
    • Rating:
    Das neue CMOS-optimierte 5.5nm H-beta Filter begeistert
    Ich hatte die Möglichkeit die neuen Baader Filter zu testen. Ziel des Tests war die Beurteilung der Halo-Situation und der Vergleich der Kontraste an einem geeigneten Objekt. Verglichen wurde das neue CMOS-optimierte 5.5nm H-beta Filter gegen das alte 8.5nm H-beta Filter vom 2014, welches sich glücklicher Weise in meinem Besitz befand.

    Am Ende dieses Tests habe ich es mir erlaubt ein "pretty picture" zu belichten, welches unter auf Anhieb als „Top Picture" nominiert werde!

    Das neue CMOS-optimierte 5.5nm H-beta Filter begeistert, denn:
    Wenn ein Halo heller wird als das eigentliche Signal, dann wird die EBV zur Glücksache. Die Rekonstruktion des Signals unter dem Halo wird zu einer subjektiven Einschätzung. Beim neuen CMOS-optimierte 5.5nm H-beta Filter störenden die Halos praktisch nicht mehr, und „Halo-Reste“ an sehr hellen Sternen können bei der EBV leicht beseitigt werden.
    Der Kontrast ist nun auf einem exzellenten Niveau angekommen. Das neue Filter liefert photographisch sogar bei f/1.9 so kontrastreiche Daten, dass man glauben könnte, dass es sich um Ha-Daten handelt. Im Vergleich zum alten H-Beta Filter ein Quantensprung!
    Herr Andreas Bringmann war einer unserer ersten Tester der neuen CMOS-optimierten Baader Ultra-Highspeed F/2 Filter. Die neuen f/2 Ultra-Highspeed-Filter führten für ihn nicht nur zu erstaunlichen Bildern, sondern ermöglichten sogar den fotografischen Nachweis des neu entdeckten planetarischen Nebels StDr13.

    Nun hatte Hr. Bringmann die Möglichkeit die neuen CMOS-optimierten Baader 5.5nm H-Beta Filter zu testen. Verglichen wurde das neue CMOS-optimierte 5.5nm H-beta Filter gegen das alte 8.5nm H-beta Filter vom 2014, welches sich im Besitz von Herrn Bringmann befand.

    Lesen Sie hier den gesamten Testbericht von Hr. Bringmann
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