Baader Ultra-Narrowband H-alpha 3,5nm Filter

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Baader Ultra-Narrowband H-alpha 3,5nm Filter

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Regular Price: € 257.00

Special Price Incl. Tax: € 192.75

Price excl. German VAT tax (19%): € 161.97

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  • Precision grade enforced H-alpha filter for f/10 to f/3.5 optical systems
  • Opens up the extremely narrow 3,5nm H-alpha world
  • This enforced contrast results in even fainter stars, providing more signal of faintest nebulae detail
  • Manufacturing such ultra-narrow filter does require extreme coating homogeneity and very high CWL precision, which these filters are designed for. CWL= Center-wavelength / FWHM= full width half maximum.

Note: In general this DeepSky Ultra-Narrowband H-alpha Filter is not suitable for solar observation. The Halfbandwidth of 3,5nm equals 35 Ångstroem, high-quality H-alpha solar filter from SolarSpectrum start at 0.8 Ångstroem. At favorable conditions experiments might still be possible, although at lesser quality. Read more about it (in german) here:

We explicity warn you to observe the sun with a 3.5nm H-alpha Filter. This may be possible with a camera, but under no circumstances with the naked eye. Due to eye safety reason we must generally advise against experiments of this kind.

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Regular Price: € 257.00

Special Price Incl. Tax: € 192.75

Price excl. German VAT tax (19%): € 161.97

Product Questions

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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)
I've got filter set h-alpha,h-beta,sII,oIII for full frame ccd, when will arrive the filter size 1.25" for h-alpha 3.5nm?
Question by: Nazario Montuori on Apr 30, 2017 11:39:00 PM | 1 Answer(s)
Do all Baader narrowband filter both UV and IR as well? I am thinking of using them with a Full Spectrum DSLR. Thanks.
Question by: Jon on Nov 1, 2016 11:59:00 PM | 1 Answer(s)
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)
I understand your 3.5nm Ha filter in 1.25" size will become available later this year. When will you produce 3.5nm filters of the same size in SII and OIII? Thank you.
Question by: Peter on Jul 3, 2017 10:44:35 PM | 1 Answer(s)
Can this filter be used as an internal energy rejection filter for H-alpha solar observation on 140mm and 60mm refractors? The ERF would be placed in front of the diagonal mirror, and the etalon behind the diagonal.

What is the filter's throughput beyond 1000nm?
Question by: Desiderius on Jul 1, 2020 11:40:00 PM | 1 Answer(s)
Can you share actual transmission characteristics? Does this filter allows NII wavelength to pass?
Question by: Thomas on Aug 16, 2020 10:15:00 PM | 1 Answer(s)
What bandwidth is recommended for H-alpha imaging at f/15?
Question by: Stephen on Sep 13, 2020 2:57:00 AM | 1 Answer(s)
Are you developing a 36mm unmounted version of this filter?
Question by: Paul Tribe on Nov 30, 2017 2:43:00 PM | 1 Answer(s)
Are all Baader narrowband filters parfocal? I mean could I use extreme narrowband filters like the Baader 3.5nm with normal narrowbands like the OIII 8.5nm and expect them to be parfocal?
Thanks in advance for your time and help!
Ilias Galanis.
Question by: ILIAS GALANIS on Feb 5, 2019 9:50:00 PM | 1 Answer(s)
Do you have any plans to make a 1.25" of this filter?
Thank you,
Elias Galanis.
Question by: Elias Galanis on Jan 24, 2018 3:18:00 PM | 1 Answer(s)
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Thomas 162/06/2020 11/06/202017:28
  • Rating:
Star remover
This 50.4mm Ha filter gives nice and clean images on my MN190 scope. All moonlight and city lights are completely removed (along with most of the stars!!!). Stacking is a bit more difficult with the 3.5nm bandwidth, because of the missing stars, but it works well even with an RGB camera. The attached picture is a raw test image made with an ASI294MC PRO, with no calibration at all, under a Bortle class 5 sky, with Orion only 17° above the horizon, 25° away from the nearly full moon. Stack of 12 images, 30s each. More difficult conditions would force anyone to choose a different target... Next time I'll try to measure it's bandwidth with something bright above my head.
  • 3.5nm bandwidth, no noticeable halos and reflections
  • Price, companion OIII and SII filters are rarely available in the same size, no kit available...
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Luc Jaspers 287/10/2019 15/10/201919:45
  • Rating:
Nice contrast in very lightpolluted citycenter
I live in Brussels, the sky is always orange. On a good light I can see max 30 stars.
And with this filter I can take nice pictures thru my Skywatcher 25cm quattro scope.
Here you see the result of 6000 s exposure. Not bad considering it is taken from the citycenter.
  • No lightpollution any more
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Rüdiger 24/01/2019 25/01/201910:21
  • Rating:
Hervorragender Filter
Ich habe bis jetzt nur mit dem Ha 35nm gearbeitet. Nun wollte ich aber feinere Strukturen erfassen. Da aber der Ha 35nm doch sehr überlappend mit dem Rot-Filter ist, war ein Filterwechsel unausweichlich.
Nach langem Abwägen zwischen der 7nm und 3,5nm Variante, habe ich mich für den 3,5nm Filter entschieden - und ich habe es nicht bereut.
Da ein Bild mehr als 100 Worte sagt, anbei eine Testaufnahme, die ich in einer der wenigen wolkenlosen Nächte machen konnte (Bemerkenswert: Nahezu Vollmond in ca. 16 Grad Distanz):

Das einzige Problem, das mir aufgefallen ist, ist die tückische Erstellung von Flat-Frames. Ich verwende dazu eine LED Light-Box. Diese scheint jedoch in dem Frequenzband ausgesprochen schwach zu emittieren. Dadurch waren die Ha-Flats ausgesprochen schlecht (siehe dazu auch zweites Bild). Eventuell bringt hier eine Luminanzfolie bessere Ergebnisse.

Datum: 19.01.2019
Objekt: Rosettennebel, NGC2244
Teleskop: Explore Scientific Carbon 102mm / f702mm
Kamera: ATIK 16200, BIN2x2, -40 Grad
Subframe: Einzelaufnahme 600s mit Ha 3,5nm Filter
Bearbeitung: BIAS, Dark und Flat-Korrektur; Delinearisiert in Pixinsight
  • Gewohnt gute Baader Qualität
  • Keine negativen Erfahrungen bis jetzt
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