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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.
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"
SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"

SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2"

by SVBONY
SKU SV-W9187DB
$93.33 - $93.33
$93.33
$93.33 - $93.33
$93.33
Price Match Policy!
  • Isolates the 656.3nm H-Alpha wavelength
  • Aggressive 5nm Full Width at Half Maximum (FWHM) bandpass
  • Peak transmittance of ≥90% for high signal throughput
  • Deep ≥OD5 blocking of unwanted wavelengths from 300-1000nm
  • Standard 2-inch (M48x0.75 thread) housing
  • 44mm clear aperture minimizes vignetting on larger sensors
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • SVBONY SV227 2" H-Alpha 5nm Narrowband CCD Filter

    The SVBONY SV227 2" H-Alpha 5nm Narrowband CCD Filter isolates the critical 656.3nm hydrogen-alpha emission line with a tight 5nm bandpass for maximum contrast. With peak transmittance rated at ≥90% and deep out-of-band blocking of ≥OD5 across the 300-1000nm range, this filter passes nebula signal while aggressively rejecting light pollution. The optical substrate is polished to a 1/4λ surface parallelism, ensuring that the high resolution of your telescope is preserved in the final image.

    Isolating H-Alpha: The 5nm Bandpass at 656.3nm

    The core of the SV227 is its ability to isolate a very specific slice of the red spectrum. The 5nm FWHM (Full Width at Half Maximum) is narrow enough to dramatically darken skyglow from city lights and moonlight, causing the faint structures within emission nebulae like the Heart Nebula (IC 1805) or Veil Nebula (NGC 6960) to stand out with stark contrast. Centered precisely on the 656.3nm H-alpha line, it captures the most dominant wavelength emitted by these deep-sky targets.

    Optical Integrity: ≥90% Transmission and OD5 Blocking

    A narrowband filter is only as good as its signal efficiency and its ability to block unwanted light. The SV227's coatings achieve a peak transmittance of ≥90%, ensuring that the faint H-alpha signal you're collecting isn't lost. Just as importantly, its ≥OD5 blocking rejects off-band light by a factor of 100,000, preventing bloated stars and washed-out backgrounds from compromising your long exposures.

    • 1/4λ Surface Parallelism: Advanced polishing ensures the filter will not introduce distortions or degrade the sharpness of your optical system.
    • 1.85mm Substrate: The thin glass substrate helps minimize focus shift when switching between filters in a wheel.
    • Surface Quality (60/40): A clean, professional-grade surface finish minimizes scatter and artifacts.

    Mechanical Design: 2-Inch Format with 44mm Clear Aperture

    The SV227 is housed in a standard 2-inch cell with M48x0.75 threads, making it compatible with virtually all modern filter wheels, filter drawers, and accessories. Its generous 44mm clear aperture provides an unvignetted field for cameras with APS-C or even larger sensors, ensuring even illumination from edge to edge. The filter features a single-thread design, intended for use within a filter holder rather than for stacking directly onto other filters or eyepieces.

    5nm vs. Wider Bandwidths: Contrast and Signal Trade-offs

    Choosing a bandwidth is a critical decision in narrowband imaging. The SV227's 5nm bandpass offers a significant advantage over wider 7nm or 12nm filters, especially under light-polluted skies, by providing a darker background and higher contrast. While a narrower 3nm filter might offer even more contrast, it requires longer exposure times to achieve the same signal level. The 5nm design represents a highly effective balance, delivering excellent contrast without demanding excessive sub-exposure times, making it a practical choice for a wide range of telescopes and sky conditions.

  • What is the main advantage of the SVBONY SV227's 5nm bandwidth?

    The primary advantage of the 5nm bandwidth is significantly higher contrast compared to wider filters (like 7nm or 12nm). It does a better job of rejecting light pollution, moonlight, and natural skyglow, making faint nebula details pop against a darker background. This is especially beneficial for imagers in suburban or urban locations.

    How will the SV227 5nm H-Alpha filter perform on the Pelican Nebula (IC 5070) from a suburban backyard?

    The SV227 is ideal for this scenario. The Pelican Nebula is rich in H-alpha emissions. From a suburban backyard, the 5nm bandpass will effectively isolate the nebula's 656.3nm signal from city skyglow, allowing you to capture its intricate dust lanes and bright ionization fronts with much greater clarity than you could with a broadband or wider narrowband filter.

    Is the SV227 2-inch filter a good match for a fast f/4 Newtonian telescope?

    Yes, but with a consideration. Fast optical systems can cause a slight "band-shift" in narrowband filters. While the SV227's 5nm bandpass is generally robust enough for systems down to f/4, it offers a good balance between the contrast benefits of narrowband and tolerance for faster optics. The high ≥90% transmittance also helps gather signal efficiently in these fast systems.

    What does ≥OD5 blocking mean for my astrophotos with the SV227 filter?

    OD5 blocking means the filter reduces unwanted light outside its 5nm bandpass by a factor of at least 100,000. For your images, this translates to:

    • Cleaner Backgrounds: It eliminates gradients caused by light pollution or moonlight.
    • Tighter Stars: It prevents halos and bloating around bright stars caused by out-of-band emissions (like near-infrared).
    • Higher Contrast: By ensuring only the desired 656.3nm light reaches the sensor, the nebula signal is maximized relative to the background noise.

    The SVBONY SV227 filter has a single M48x0.75 thread. Can I stack it with other filters?

    No, this filter is not designed for stacking. The Single Thread: Yes specification indicates it has threads on one side only, meant for securing it into a filter wheel or filter drawer. It does not have female threads on the opposite side to attach another filter directly to it.

    Is the 1.85mm substrate thickness of the SV227 filter parfocal with other filters?

    The 1.85mm thickness is quite thin, which helps minimize focus shift between filters. However, achieving perfect parfocal performance across an entire set of filters from different manufacturers is rare. While the SV227 is designed to be close, you should expect to make minor focus adjustments when switching between it and other filters, especially those with different substrate thicknesses.

  • Filter Type H-Alpha Narrowband
    Size 2-Inch
    Center Wavelength (CWL) 656.3nm
    Bandpass (FWHM) 5nm
    Peak Transmittance ≥90%
    Blocking Range 300-1000nm
    Blocking Depth ≥OD5
    Clear Aperture 44mm
    Substrate Thickness 1.85mm
    Surface Quality 60/40
    Surface Parallelism 1/4λ
    Parallelism 30"
    Thread M48x0.75
    Threading Single Thread
    Net Weight 12.5g / 0.44oz

    • SVBONY SV227 2" H-Alpha 5nm Filter

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  • SVBONY 1-Year Warranty