Baader O-III Ultra-Narrowband-Filters (4nm) – CMOS-optimized

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Baader O-III Ultra-Narrowband-Filters (4nm) – CMOS-optimized

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€ 244.00 Price excl. German VAT tax (19%): € 205.04

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Which side should face the telescope?
  • Baader O-III Ultra-Narrowband Filter – Premium Grade
  • 4 nm FWHM, recommended for optical systems from > f/3.4
  • 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 telescope-sided black outer rim
  • Optimized for modern CMOS cameras, but likewise excellent for CCD camera technologies

Baader Narrowband-/Highspeed Filter Selector

To make it easy for you in the future to decide which kind of Highspeed (or Narrowband) filter you need for your telescope, please check our Filter-Selector, that provides you the correct individual graph based on your entriest, in which you can find the perfect filter for your telescope by f/ration and central obstruction.

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€ 244.00 Price excl. German VAT tax (19%): € 205.04

Product Questions and Answers

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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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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:
    Baader CMOS Optimized Filters: Unleashing the Full Potential of Astrophotography

    Baader Blogpost:
    New CMOS-optimized Baader Filters

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    Additional Information

    Technical Data not yet specifiedPlease choose product variant from dropdown above to see technical data of your chosen product

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    Overall Average Rating:
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    3 Item(s)

    Anssi 280/10/2023 08/10/202310:51
    • more than 6 month(s)
    • Rating:
    Great filter
    Good transmission from corner to corner with my f/3.6 wide field configuration at least on an 28mm * 22mm sensor. The filter diameter also generously covers entire chip.

    This filter works very well also on my color CMOS camera as both the blue and green pixels have great QE at 500 nm. This is 3/4 of all the pixels.
    • The narrow bandwidth works very well for urban and rural skies
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    F. Meschia 322/11/2021 19/11/202107:23
    • Rating:
    This is Baader LifeCoat!
    I purchased one of the new CMOS-optimized, Ultra-Narrowband 4nm OIII filters, in 31mm size (item no. 2961401). After some disappointing results due to flats that would overcorrect my lights, I found that my filter has a dark band that correlates with the position of overcorrected portions of my subs.

    Baader recommended me to obtain a replacement filter, and to return my filter so that they can examine it.

    And now I just wanted to let you know that, following after this message my dealer has instructed me to send my filter to them, and provided me with a replacement filter, free of any charge The new filter doesn't show any visual defect, and produces very fine images.
    The support from Baader Planetarium, as well as my dealer, in this matter has been amazingly good and I greatly appreciate that

    Attached you can see my first test HOO image, produced with my Baader 3.5nm H-alpha, and with the new 4nm O-III
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    Frank Küber 203/07/2021 23/07/202113:41
    • Rating:
    O-III ULTRA-NARROWBAND-FILTER (4NM) - 36mm (ungefasst)
    First Light (18.7 - 22.7.2021, zunehmender Mond (55% - 98%), Standort Hochtaunus mit div. Straßenbeleuchtung): Im Gegensatz zu den Vorgängermodellen (7nm, 36mm ungefasst) und 2" gefasst (4,5nm und 7nm) im gleichen Setup (1200mm F8 APM LZOS und 82mm Riccardi Flattner, Kamera ZWO ASI 2600) keinerlei Reflexe oder Sternhalos. Definitiv eine Verbesserung. Der entsprechende Ha Filter zeigt ebenfalls eine ausgezeichnete Performance. Den SII Filter habe ich noch nicht getestet.
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