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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 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"
SVBONY SV227 OIII 5nm Narrowband Filter - 2"

SVBONY SV227 OIII 5nm Narrowband Filter - 2"

by SVBONY
SKU SV-W9187DC
$93.33 - $93.33
$93.33
$93.33 - $93.33
$93.33
Price Match Policy!
  • Isolates the Oxygen III emission line at 500.7nm
  • Extremely narrow 5nm Full Width at Half Maximum (FWHM) bandpass
  • Achieves ≥90% peak light transmittance at the OIII line
  • Standard 2-inch format with M48x0.75 filter threads
  • Precision 1.85mm thick substrate with 1/4λ surface parallelism
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • SVBONY SV227 OIII 5nm 2-inch Telescope Filter

    The SVBONY SV227 OIII 5nm 2-inch filter is engineered to isolate the doubly ionized oxygen signal from planetary nebulae and supernova remnants with extreme prejudice. Its tight 5nm bandpass is centered precisely at the 500.7nm wavelength, achieving ≥90% peak transmittance to capture faint structures while suppressing overwhelming light pollution. The optical substrate is held to a 1/4λ parallelism with a 60/40 surface quality, ensuring the filter preserves the sharpness of your optical system across its full 44mm clear aperture.

    Isolate Nebulae with a 5nm FWHM Bandpass

    The core of the SV227 filter's imaging capability is its extremely narrow 5nm Full Width at Half Maximum (FWHM). This tight window, centered at 500.7nm, passes light almost exclusively from the OIII emission line, which is critical for revealing the delicate, glowing structures within planetary nebulae like the Dumbbell Nebula (M27) or the faint, expansive shells of supernova remnants like the Veil Nebula (NGC 6960).

    By rejecting nearly all other wavelengths across its 300-1000nm blocking range, the filter dramatically increases contrast and allows you to pull faint details out from even heavily light-polluted skies. With a peak transmittance of ≥90%, the filter passes the maximum amount of critical signal to your sensor, keeping exposure times manageable for such a narrow bandpass.

    1/4λ Substrate for Sharp Stars Across the Field

    A filter is part of your optical train, and any imperfection can degrade the final image. The SV227 is built on a 1.85mm thick glass substrate polished to a 1/4λ surface parallelism and a 60/40 surface quality. This level of precision prevents the filter from introducing astigmatism or other distortions that can elongate stars, especially towards the edge of the field.

    The 30" parallelism specification ensures the two faces of the filter are almost perfectly parallel, minimizing any wedge effect that could cause image shift or focus problems when swapping between filters in a wheel. This attention to optical quality means your stars remain as tight and round as your telescope's optics can deliver.

    2-Inch Format with a 44mm Clear Aperture

    Designed for modern imaging setups, the SV227 comes in a standard 2-inch cell with M48x0.75 threads. This makes it directly compatible with most 2-inch filter wheels, filter drawers, and dedicated astronomy cameras. The filter provides a generous 44mm clear aperture, large enough to fully illuminate full-frame sensors without introducing vignetting from the filter cell itself.

    Despite its robust optical specifications, the filter is remarkably light, weighing only 12.5g. This low mass helps maintain the balance of your imaging train and reduces the strain on focuser motors and filter wheel mechanisms during operation.

    5nm vs. Wider OIII Filters: The Contrast Trade-Off

    Choosing a narrowband filter involves a trade-off between contrast and exposure time. The SV227's 5nm bandpass represents a move towards higher contrast and better suppression of unwanted light.

    • SVBONY SV227 5nm Filter: Its primary advantage is maximum contrast. It darkens the sky background more effectively than wider filters, making it superior for pulling out the faintest details from emission nebulae, especially from urban or suburban locations. The trade-off is that it requires longer sub-exposure times to gather the same amount of signal as a wider filter.
    • Wider 7nm or 12nm Filters: These filters are more forgiving, allowing for shorter sub-exposures. However, they let in more skyglow and continuum emission from stars, resulting in a brighter background and slightly lower overall contrast on the nebula itself. They are often a good starting point, but the 5nm is the specialist's tool for difficult targets.

  • How will the SVBONY SV227 5nm filter perform on the Veil Nebula (NGC 6960) from a Bortle 7 zone?

    The SV227 is ideal for this exact scenario. The Veil Nebula is a classic OIII-rich supernova remnant, but its faint, filamentary structure is easily lost in skyglow. The tight 5nm bandpass will aggressively reject the Bortle 7 light pollution, dramatically increasing contrast and making the nebula's delicate wisps stand out against a dark background.

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

    The 1.85mm thickness is very close to the thickness of many other popular filter brands. While perfect parfocality is never guaranteed across different manufacturers, this thickness should result in minimal focus shift when used in a filter wheel alongside other modern narrowband or LRGB filters. You may need only a very small focus adjustment.

    What does the ≥OD5 blocking on the SV227 OIII filter mean for my images?

    OD5 blocking means the filter blocks out-of-band light by a factor of 100,000 (Optical Density 5). This is a high level of blocking that ensures light from streetlights, the moon, and unwanted wavelengths from stars does not leak through and cause halos or gradients in your final image. It's a critical specification for clean, high-contrast astrophotography.

    Can I use the SVBONY SV227 OIII filter for visual observing?

    While technically possible on very bright planetary nebulae like the Ring Nebula (M57) with a large aperture telescope, it's generally not recommended. The 5nm bandpass is so restrictive that it makes the view extremely dim, and most stars will disappear entirely. This filter is designed specifically for long-exposure astrophotography, not visual use.

    Why is the 44mm clear aperture of the SV227 important?

    The 44mm clear aperture is larger than the diagonal of an APS-C sensor and nearly matches the diagonal of a full-frame sensor. This ensures that even with a fast optical system, the filter housing itself will not block light at the corners of your sensor, preventing vignetting and ensuring even illumination across your entire field of view.

    Does the M48x0.75 single thread on the SV227 filter cause any issues?

    No, this is standard. The M48x0.75 single thread is on the side of the filter that threads into your camera or filter wheel. The other side is unthreaded. This design prevents you from accidentally stacking filters, which can cause internal reflections and degrade image quality. It ensures the filter is always mounted correctly in the optical train.

  • Filter Type OIII Narrowband
    Size 2-Inch
    Center Wavelength (CWL) 500.7nm
    Bandwidth (FWHM) 5nm
    Peak Transmittance ≥90%
    Blocking Range 300-1000nm
    Blocking Depth ≥OD5
    Substrate Thickness 1.85mm
    Clear Aperture 44mm
    Surface Quality 60/40
    Surface Parallelism 1/4λ
    Parallelism (Angle) 30"
    Thread M48x0.75
    Threading Single-Sided
    Net Weight 12.5g / 0.44oz
  • SVBONY Warranty Policy