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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Baader 6.5nm Narrowband Filter Set - CMOS-Optimized H-alpha/O-III/S-II

Baader 6.5nm Narrowband Filter Set - CMOS-Optimized H-alpha/O-III/S-II

by Baader Planetarium
SKU BAA-2961650
$512.00 - $1,287.00
$512.00
$512.00 - $1,287.00
$512.00
Price Match Policy!
  • 6.5nm Narrowband Filter Set for H-alpha, O-III, and S-II
  • Optimized specifically for modern CMOS astronomy cameras
  • Reflex-Blocker™ coatings prevent halos and internal reflections
  • Life-Coat™ sealed edges for enhanced durability and longevity
  • Planeoptically polished substrates ensure maximum image sharpness
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader 6.5nm Narrowband Filter Set - CMOS-Optimized H-alpha/O-III/S-II

    The Baader 6.5nm Narrowband Filter Set is engineered for modern CMOS sensors, combining a tight 6.5nm bandpass with advanced coatings to isolate critical H-alpha, O-III, and S-II emission lines without generating artifacts. This 6.5nm design delivers high-contrast images by aggressively rejecting light pollution and moonlight, while the CMOS-optimization eliminates the halos around bright stars that plague filters not designed for highly reflective modern sensors.

    CMOS-Optimized Coatings: Suppressing Halos and Reflections

    Modern CMOS sensors are notoriously reflective compared to older CCD technology. Baader addresses this directly with advanced Reflex-Blocker™ coatings, which are specifically designed to neutralize reflections between the filter and the sensor. This technology effectively eliminates the halos and ghost images that can ruin an otherwise perfect exposure, even with very bright stars like Alnitak in the field of view.

    The 6.5nm Bandpass: High Contrast for Nebula Imaging

    The 6.5nm full width at half maximum (FWHM) strikes a critical balance between contrast and signal strength. This bandpass is narrow enough to darken the sky background significantly and enhance faint nebular details, yet it remains efficient enough for use with a wide range of telescope focal ratios. It provides a substantial contrast boost over wider 7nm or 12nm filters without requiring the extremely long sub-exposures demanded by ultra-narrow 3nm designs.

    Uncompromised Substrate and Life-Coat Durability

    Each Baader filter is built on a planeoptically polished substrate, ensuring that it will not degrade the resolution of your optical system. The coatings are applied with Ion-Beam-Assisted Deposition (IBAD), resulting in a hard, scratch-resistant surface. Furthermore, Baader's proprietary Life-Coat™ process seals the coating edges, making them impervious to moisture and aging, guaranteeing the filter's transmission properties will not degrade over time.

    Baader 6.5nm CMOS vs. Traditional Narrowband Filters

    Older narrowband filters were designed for the less-reflective surfaces of CCD sensors. When used with a modern CMOS camera, these filters can produce prominent halos and reflections that are difficult to process out. The Baader CMOS-Optimized set solves this problem at the source.

    • Baader 6.5nm CMOS-Optimized: Features Reflex-Blocker™ coatings to absorb reflections between the filter and sensor, producing clean, halo-free stars. The coatings are also shifted to remain on-band even with fast optical systems down to f/3.5.
    • Traditional Narrowband Filters: Lack specialized anti-reflection coatings for the camera side, leading to artifacts with reflective CMOS sensors. Their passbands can also shift significantly with fast focal ratios, reducing signal.

  • Why are these Baader 6.5nm filters "CMOS-Optimized"?

    They are "CMOS-Optimized" because they feature Baader's proprietary Reflex-Blocker™ coatings. These coatings are specifically designed to prevent halos and internal reflections caused by the highly reflective nature of modern CMOS sensor assemblies. This results in cleaner images with higher contrast and no distracting artifacts around bright stars.

    What is the advantage of a 6.5nm bandpass over a wider 7nm or 12nm filter?

    A narrower bandpass like 6.5nm provides significantly higher contrast by rejecting more unwanted light from streetlights, moonlight, and natural skyglow. This makes faint nebula structures stand out more clearly against the background sky compared to wider filters.

    How will the Baader 6.5nm O-III filter perform on the Veil Nebula (NGC 6960) with a fast refractor?

    Excellent. The Veil Nebula is a strong O-III emitter, and the 6.5nm bandpass will produce extremely high contrast, revealing the delicate, filamentary structure of the supernova remnant. Baader's coatings are also designed to minimize band-shift with fast optics, ensuring you capture maximum signal even with a fast refractor.

    Are the filters in the Baader 6.5nm Narrowband Set parfocal?

    Yes, Baader manufactures these filters to be parfocal. All filters in the set are made with the same substrate thickness, meaning you should not need to refocus, or will only need a minimal adjustment, when switching between the H-alpha, O-III, and S-II filters. This is a major time-saver for automated imaging runs.

    I'm imaging the Heart Nebula (IC 1805) with my SCT at f/7. Is 6.5nm a good choice?

    Yes, 6.5nm is an excellent choice for an f/7 system. The Heart Nebula is rich in all three emission lines (H-alpha, O-III, and S-II). The 6.5nm bandpass will provide the contrast needed to separate the intricate structures within the nebula, and an f/7 optical system is efficient enough to gather plenty of signal without requiring excessively long sub-exposures.

    Can I use the Baader 6.5nm H-alpha filter for solar viewing or imaging?

    Absolutely not. These are deep-sky emission-line filters and are not safe for any kind of solar observation. Attempting to view the sun through this filter will cause immediate and permanent eye damage. For solar work, you must use a dedicated, certified solar filter designed for that purpose.

  • Filter Type Narrowband Emission Line (SHO)
    Bandpass (FWHM) 6.5nm
    Wavelengths H-alpha, O-III, S-II
    Primary Feature CMOS-Optimized with Reflex-Blocker™ Coatings
    Durability Life-Coat™ Sealed Coating Edges
    Available Formats 1.25" Mounted, 2" Mounted, 31mm Unmounted, 36mm Unmounted, 50.4mm Unmounted, 50x50mm Square, 65x65mm Square
    Net weight (kg) 0.02 (1.25" Round Mounted)
    0.04 (2" Round Mounted, 50.4mm Round Unmounted Filter)
    0.01 (36mm Round Unmounted Filter, 31mm Round Unmounted Filter)
    0.06 (50x50mm Square Filter)
    0.10 (65x65mm Square Filter)
    Filter shape round (1.25" Round Mounted, 2" Round Mounted, 36mm Round Unmounted Filter, 50.4mm Round Unmounted Filter, 31mm Round Unmounted Filter)
    square (50x50mm Square Filter, 65x65mm Square Filter)
    Single or Set? Filter-Set
    Filter mounted Mounted (LPFC 6mm) (1.25" Round Mounted, 2" Round Mounted)
    Unmounted (36mm Round Unmounted Filter, 50.4mm Round Unmounted Filter, 50x50mm Square Filter, 65x65mm Square Filter, 31mm Round Unmounted Filter)
    Filter Usage CMOS, CCD, H-alpha, O-III, S-II
    Special Features CMOS-optimized with Life-Coat™
    Filter Thickness (without cell) 2 mm (1.25" Round Mounted, 2" Round Mounted, 36mm Round Unmounted Filter, 31mm Round Unmounted Filter)
    3 mm (50.4mm Round Unmounted Filter, 50x50mm Square Filter, 65x65mm Square Filter)
    CWL (Central Wavelength) 656.3 nm / 500.7 nm / 671.7 nm
    AR-Coating Reflex-Blocker™ hard coated, planeoptically polished
    Suitable for f/ratio > f/3.4
  • Baader Planetarium Warranty