Baader 3.5 / 4nm Ultra-Narrowband Filter-Set – CMOS-optimized (H-alpha / O-III / S-II)

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Baader 3.5 / 4nm Ultra-Narrowband Filter-Set – CMOS-optimized (H-alpha / O-III / S-II)

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€ 719.00 Price excl. German VAT tax (19%): € 604.20

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  • Baader H-alpha / O-III / S-II Ultra-Narrowband Filter Set – Premium Grade
  • 3.5 / 4 nm FWHM (to harmonize the exposure time from H-alpha with O-III / S-II), recommended for optical systems from f/10 to f/3.5
  • For highest contrast even at strongest light pollution, minimizes star size, emphasizes finest nebula detail – indispensable under Bortle 9/8/7/(6) skies
  • 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 black frontside outer rim
  • Optimized for modern CMOS cameras, but excellent for CCD camera technologies

We explicitly warn against observing the sun with a DeepSky 3.5 nm (equivalent to 35 Ångstroem) H-alpha narrowband filter, specialized solar chromosphere and prominence filters from SolarSpectrum start at 0.8 Ångstroem. Photographic experiments with a camera are theoretically possible, but by no means observe the sun with naked eyes – you endanger your eyesight!

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€ 719.00 Price excl. German VAT tax (19%): € 604.20

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)
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)
What are the advantages and disadvantages of ultra-narrowband filters (3.5 / 4nm) compared to 6.5nm narrowband filters?
DSO photography from the skies Bortle 7 with refractor f7.5 and Newton f4.8
Question by: mymverger on Jul 12, 2021 1:27:00 PM | 1 Answer(s)
Hello, I have a couple of questions:
1) Will you take orders for the 65mm square versions as soon as orders open ?
2) Is there a new LRGB set that has Life-Coat and is CMOS optimised ? What is the link if so ?
I am very excited about your new filters !
Question by: Marc on Jun 21, 2021 4:58:00 PM | 1 Answer(s)
I'm thinking about adding an f/3.3 Epsilon to my stable of telescopes (I also use an f/4 and f/6 telescope). These are rated down f/3.5. I don't know that I could justify buying two sets of narrowband filters. How much would the f/0.2 difference really make? Could these still be used with good effect?
Question by: Chris on Jul 7, 2021 6:04:00 PM | 1 Answer(s)


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:

    New CMOS-optimized Baader (Ultra-)Narrowband and Highspeed Filters

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