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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 f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II
Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II

Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II

by Baader Planetarium
SKU BAA-2961660
$548.00 - $1,310.00
$548.00
$548.00 - $1,310.00
$548.00
Price Match Policy!
  • Set of 3 Narrowband Filters: H-alpha, O-III, and S-II
  • 6.5nm Bandpass for high-contrast imaging
  • Optimized for f/2 to f/3.5 High-Speed Optical Systems
  • Pre-shifted bandpass prevents signal loss from steep light cones
  • CMOS-optimized with Reflex-Blocker™ coatings to eliminate halos
  • Sealed coating edges prevent moisture intrusion and aging
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader 6.5nm f/2 Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II

    The Baader 6.5nm f/2 Highspeed Filter Set contains three essential narrowband filters (H-alpha, O-III, S-II) specifically engineered to maintain peak transmission when used with ultra-fast astrographs like Celestron RASA or Hyperstar systems. Standard narrowband filters suffer significant signal loss at focal ratios faster than f/4, but this 6.5nm set is pre-shifted to perfectly align with the emission lines from an f/2 light cone, ensuring maximum signal capture. This optimization allows modern CMOS sensors to record deep, high-contrast images of emission nebulae without the reflection halos or bandpass-shift issues that compromise data from fast optical systems.

    Designed for f/2 Systems: Pre-Shifted for Maximum Signal

    In a fast optical system, light rays approach the filter at a very steep angle, causing a phenomenon known as bandpass shift, where the filter's central wavelength shifts towards blue. A standard narrowband filter used at f/2 can shift so much that it partially blocks the very emission line you're trying to capture. Baader's f/2 Highspeed filters solve this by pre-shifting the central wavelength of the bandpass, ensuring that at f/2, it is perfectly centered on the H-alpha, O-III, or S-II line for peak transmission.

    CMOS-Optimized for 6.5nm Signals: Halation and Reflection Control

    Modern CMOS sensors, while incredibly sensitive, are also highly reflective. When paired with traditional filters, this can create strong halos and internal reflections around bright stars. The Baader Highspeed filters incorporate advanced Reflex-Blocker™ coatings that are hardened and optimized to suppress these reflections, delivering clean stellar profiles. Additionally, the coating edges are sealed (Life-Coat™), making them exceptionally durable and resistant to degradation from moisture, ensuring their high transmission for years of use.

    6.5nm Bandpass: High Contrast for Emission Nebulae

    The 6.5nm full width at half maximum (FWHM) strikes a critical balance between contrast and signal acquisition speed. This bandpass is narrow enough to dramatically darken the sky background, isolating faint nebular structures from moonlight and urban light pollution. At the same time, it is wide enough to deliver a strong signal, which is crucial for capturing data efficiently with fast f/2 optical systems where exposure times are already significantly reduced.

    Baader f/2 Highspeed vs. Standard Narrowband Filters

    The choice between this f/2 Highspeed set and a standard narrowband filter set comes down to your telescope's focal ratio.

    • Standard Filters (f/4 and slower): These filters are designed for the shallower light cones of most refractors, SCTs, and Newtonians. Using them on an f/2 system results in significant signal loss due to bandpass shift.
    • Baader f/2 Highspeed Filters: These are purpose-built for systems from f/2 to f/3.5. Their pre-shifted design maximizes signal. Using them on a slower f/8 telescope is a trade-off; the filter's center wavelength will be slightly offset from the emission line, resulting in a suboptimal, though still usable, signal.

  • What makes the Baader 6.5nm f/2 Highspeed filters different from standard narrowband filters?

    The key difference is their pre-shifted bandpass. Standard filters are designed for f/4 or slower systems. When used at f/2, the steep light cone shifts their transmission window, blocking part of the nebula's light. The Baader f/2 Highspeed filters are manufactured to be perfectly on-band when used at f/2, ensuring maximum signal throughput.

    Can I use the Baader f/2 filters on my f/8 Ritchey-Chrétien telescope?

    While you can, it is not optimal. These filters are pre-shifted for an f/2 light cone. On an f/8 system, the filter's bandpass will be slightly blue-shifted relative to the target emission line, resulting in a small reduction in signal. For f/8 systems, a standard narrowband filter designed for slower focal ratios will deliver better results.

    What does "CMOS-Optimized" mean for the Baader Highspeed Filter Set?

    It refers to the advanced Reflex-Blocker™ coatings applied to the filters. Modern CMOS sensors are very reflective, which can cause halos and artifacts around bright stars. These specialized coatings are designed to suppress these reflections, producing cleaner images with tighter star profiles, even on very bright targets.

    How will the 6.5nm Baader filters perform on the Horsehead Nebula (Barnard 33) with my RASA 8?

    This filter set is an ideal match for imaging the Horsehead Nebula with a RASA 8. The f/2 focal ratio of the RASA is exactly what these filters are designed for. The 6.5nm H-alpha filter will provide excellent contrast to define the dark nebula against the glowing background of IC 434, capturing sharp detail with very short exposure times.

    Are these Baader f/2 filters parfocal?

    Yes, Baader Planetarium engineers their CMOS-optimized filters to be parfocal. When you switch between the H-alpha, O-III, and S-II filters in this set, you should see minimal to no change in focus, saving valuable imaging time by eliminating the need to refocus with each filter change.

    Why would I choose a 6.5nm bandpass over a narrower 3nm filter for my f/2 system?

    For an f/2 system, a 6.5nm bandpass is often a better compromise. While a 3nm filter provides higher contrast, it's more sensitive to bandpass shift and collects photons more slowly. The 6.5nm width provides excellent contrast while maintaining a very high signal acquisition rate, which is the primary advantage of using an f/2 astrograph.

  • Filter Set H-alpha, O-III, S-II
    Bandpass (FWHM) 6.5nm
    Optimized Focal Ratio f/2 to f/3.5
    Coatings Reflex-Blocker™, Life-Coat™
    CMOS Optimized Yes
    Available Sizes 1.25" Mounted, 2" Mounted, 31mm Unmounted, 36mm Unmounted, 50.4mm Unmounted, 50x50mm Unmounted, 65x65mm Unmounted
    Net weight (kg) 0.02 (1.25" Round Mounted)
    0.04 (2" Round Mounted, 50.4mm Round Unmounted Filter)
    0.01 (31mm Round Unmounted Filter, 36mm Round Unmounted Filter)
    0.06 (50x50mm Square Filter)
    0.10 (65x65mm Square Filter)
    Filter shape round (1.25" Round Mounted, 2" Round Mounted, 31mm Round Unmounted Filter, 50.4mm Round Unmounted Filter, 36mm Round Unmounted Filter)
    square (50x50mm Square Filter, 65x65mm Square Filter)
    Filter mounted Mounted (LPFC 6mm) (1.25" Round Mounted, 2" Round Mounted)
    Unmounted (31mm Round Unmounted Filter, 50.4mm Round Unmounted Filter, 50x50mm Square Filter, 36mm Round Unmounted Filter, 65x65mm Square 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, 31mm Round Unmounted Filter, 36mm 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 and faster

    Note: This is a filter set containing three individual filters. Box contents may vary based on the specific size selected.

  • Baader Planetarium Warranty