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Astrodon Narrowband Filters

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  1. Astrodon Narrowband - 1.25" Mounted H-a 5 nm Filter

    Astrodon - Narrowband - 1.25" Mounted H-Alpha 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
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    (48 States)
    Model#: HA5-27R
    $330.00

  2. Astrodon - Narrowband - 1.25" Mounted Red Continuum 5 nm Filter

    Astrodon - Narrowband - 1.25" Mounted Red Continuum 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
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    (48 States)
    Model#: REDCON5-27R
    $330.00

  3. Astrodon - Narrowband - 1.25" Mounted OIII 5 nm Filter

    Astrodon - Narrowband - 1.25" Mounted OIII 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
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    (48 States)
    Model#: OIII5-27R
    $330.00

  4. Astrodon - Narrowband - 1.25" Mounted SII 5 nm Filter

    Astrodon - Narrowband - 1.25" Mounted SII 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
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    (48 States)
    Model#: SII5-27R
    $330.00

  5. FL1-AD-xx3

    Astrodon - 1.25" Narrowband filter 3 nm FWHM

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
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    FREE SHIPPING
    (48 States)
    Model#: FL1-AD-xx3
    $395.00

  6. Astrodon - Narrowband - 36mm Unmounted OIII 5 nm Filter

    Astrodon - Narrowband - 36mm Unmounted OIII 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: OIII5-36R
    $435.00

  7. Astrodon - Narrowband - 36mm Unmounted SII 5 nm Filter

    Astrodon - Narrowband - 36mm Unmounted SII 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: SII5-36R
    $435.00

  8. Astrodon - Narrowband - 36mm Unmounted  H-Alpha 5 nm Filter

    Astrodon - Narrowband - 36mm Unmounted H-Alpha 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: HA5-36R
    $435.00

  9. Astrodon - Narrowband - 1.25" Mounted OIII 3 nm Filter

    Astrodon - Narrowband - 1.25" Mounted OIII 3 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII),

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: OIII3-27R
    $490.00

  10. Astrodon - Narrowband - 1.25" Mounted SII 3 nm Filter

    Astrodon - Narrowband - 1.25" Mounted SII 3 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII),

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: SII3-27R
    $490.00

  11. Astrodon - Narrowband - 1.25" Mounted NII 3 nm Filter

    Astrodon - Narrowband - 1.25" Mounted NII 3 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII),

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: NII3-27R
    $490.00

  12. Astrodon Narrowband 1.25" Mounted H-a 3 nm Filter

    Astrodon - Narrowband - 1.25" Mounted H-Alpha 3 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII),

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: HA3-27R
    $490.00

  13. Astrodon - Narrowband - 36mm Unmounted OIII 3 nm Filter

    Astrodon - Narrowband - 36mm Unmounted OIII 3 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII),

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: OIII3-36R
    $650.00

  14. Astrodon - Narrowband - 36mm Unmounted H-Alpha 3 nm Filter

    Astrodon - Narrowband - 36mm Unmounted H-Alpha 3 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII),

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: HA3-36R
    $650.00

  15. Astrodon - Narrowband - 36mm Unmounted SII 3 nm Filter

    Astrodon - Narrowband - 36mm Unmounted SII 3 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII),

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: SII3-36R
    $650.00

  16. Astrodon Narrowband 50mm Unmounted  Red Continuum 5 nm Filter

    Astrodon - Narrowband - 50mm Unmounted Red Continuum 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: REDCON5-50R
    $725.00

  17. Astrodon - Narrowband - 50mm Unmounted OIII 5 nm Filter

    Astrodon - Narrowband - 50mm Unmounted OIII 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: OIII5-50R
    $725.00

  18. Astrodon - Narrowband - 50mm Unmounted SII 5 nm Filter

    Astrodon - Narrowband - 50mm Unmounted SII 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: SII5-50R
    $725.00

  19. Astrodon - Narrowband - 50mm Unmounted H-Alpha 5 nm Filter

    Astrodon - Narrowband - 50mm Unmounted H-Alpha 5 nm Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: HA5-50R
    $725.00

  20. Astrodon - Narrowband - 50mm Unmounted Red Continuum 5 nm Square Filter

    Astrodon - Narrowband - 50mm Unmounted Red Continuum 5 nm Square Filter

    Narrowband (NB) filters  enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

    ...
    Learn More
    FREE SHIPPING
    (48 States)
    Model#: REDCON5-50S
    $875.00

Items 1 to 20 of 32 total

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Narrowband (NB) filters enhance contrast of emission objects by accepting only a narrow range of wavelengths around the emission lines of hydrogen (H-a, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm) and others.

They can be used to image when the moon is up, thereby extending imaging time. They can be used in light-polluted locations. The narrow range of wavelengths is defined as the FWHM (full-width at half- maximum intensity). Narrower filters decrease the background noise. However, narrower filters are more difficult to manufacture consistently, and are thus more expensive. Furthermore, it is difficult to maintain high transmission through the bandpass of the filter as it becomes narrower. If the peak transmission decreases as the filter is made narrower, the emission signal decreases and the gain in S/N (signal-to-noise) is not realized. Astrodon has achieved this goal of high transmission for narrower filters. Astrodon has evolved its narrowband product line from 6 nm to 5 nm FWHM, significantly lowered the prices on all filters, and added the ultra-narrow 3 nm FWHM filters for H-a, OIII and SII. We added a Red Continuum filter (645 nm, 5 nm FWHM) that produces a star map without the H-a or SII emission in order to subtract stars from emission images. Astrodon NB filters are renowned for not producing halos around stars and not leaking NIR light. The 3 nm FWHM filters are stocked and are not custom ordered. The 3 nm OIII filter provides the best protection from the effects of moonlight, producing half the background signal of a 90% T, 6 nm FWHM filter, resulting in an increase in S/N of ~21%. This will even be larger in comparison to wide 7 or 8 nm FWHM filters.

  • 28 mm dia (1.25" mounted)., 50.4 mm dia, 49.7 x 49.7 mm square unmounted
  • 3 mm (+/-0.025) thick
  • Parfocal to f/4 and parfocal with Astrodon LRGB depending on telescope optics
  • H-a, OIII, SII, NII, Red Continuum
  • 5 nm FWHM filters guaranteed >90% transmittance (typically 94-97%)
  • 3 nm FWHM filters typically 90-92% (scan included)
  • >4 O.D. (out-of-band blocking) 300 - 1150 nm
  • 1/4 wave, striae-free fused silica substrates
  • 30 arcsecond parallelism
  • sides are blackened
  • hardest available sputtered coating for durability
  • 3 nm filters can be used on systems to f/3
  • designed to have lower blue spectral shift with faster (e.g. f/3) optics. Astrodon's Narrowband Filter FAQ