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Narrowband Filters

Narrowband imaging is what makes deep-sky astrophotography possible from a Canadian city. By passing only a few nanometres around a specific emission line, these filters reject almost all artificial light and most moonlight, so a nebula that is invisible visually from a suburban driveway becomes a viable multi-hour imaging target. David Astro stocks narrowband filters in Canada, held in Canadian inventory.

Bandwidth choice interacts with your telescope's focal ratio in ways that catch people out. Tell us your optic and camera and we will recommend a bandwidth that will actually perform in your system.

Filters

CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00

Antlia 3nm Narrowband H-alpha Pro Filter

Options available
8 variants in stock

656.3nm H-alpha Central Wavelength Small 3nm FHWM High >88% Peak Transmission Minimized halos on bright stars Description Specificat...

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CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00

Antlia 3nm Narrowband H-alpha Pro Highspeed Filter - f/2.6 to f/3.6

Options available
1 variants in stock

Pre-shifted 656.3nm H-alpha Central Wavelength for High-Speed Systems Optimized 3nm FHWM for f/2.6–f/3.6 High >90% Peak Transmission Enhanced S...

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CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00

Antlia 3nm Narrowband OIII Pro Filter

Options available
8 variants in stock

Antlia OIII Pro narrowband filter optimizes the FWHM (full width half maximum) to 3nmbandpass. As the bandwidth becomes narrower, the 3nm Pro narro...

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CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00

Antlia 3nm Narrowband OIII Pro Highspeed Filter - f/2.6 to f/3.6

Options available
1 variants in stock

Pre-shifted 500.7nm OIII Central Wavelength for High-Speed Systems Optimized 3nm FHWM for f/2.6–f/3.6 High >90% Peak Transmission Enhan...

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CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00

Antlia 3nm Narrowband SII Pro Filter

Options available
7 variants in stock

Antlia SII Pro narrowband filter optimizes the FWHM (full width half maximum) to 3nm bandpass. As the bandwidth becomes narrower, the 3nm Pro narro...

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CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00 - CA$696.00
CA$362.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00

Antlia 3nm Narrowband SII Pro Highspeed Filter - f/2.6 to f/3.6

Options available
1 variants in stock

Pre-shifted 500.7nm OIII Central Wavelength for High-Speed Systems Optimized 3nm FHWM for f/2.6–f/3.6 High >90% Peak Transmission Enhan...

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CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00 - CA$721.00
CA$375.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00

Antlia 4.5nm Narrowband H-alpha Edge Filter

Options available
8 variants in stock

Antlia H-alpha EDGE narrowband filter optimizes the FWHM (full width half maximum) to 4.5nm bandpass. The suppression of optical density (OD)5 on ...

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CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00

Antlia 4.5nm Narrowband OIII Edge Filter

Options available
8 variants in stock

Antlia OIII EDGE narrowband filter optimizes the FWHM (full width half maximum) to 4.5nm bandpass. The suppression of optical density (OD)5 on unw...

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CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00

Antlia 4.5nm Narrowband SII Edge Filter

Options available
7 variants in stock

Antlia SII EDGE narrowband filter optimizes the FWHM (full width half maximum) to 4.5nm bandpass. The suppression of optical density (OD)5 on unwa...

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CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00 - CA$497.00
CA$263.00
CA$554.00 - CA$554.00
CA$554.00
CA$554.00 - CA$554.00
CA$554.00

Antlia ALP-T Dual Band Ha&OIII 3nm

ANT-ALP-T-3NM-HAOIII
5 in stock

Precise Narrowband Filtering for Exceptional Contrast Enhanced Transmission for Superior Signal-to-Noise Ratio ...

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CA$554.00 - CA$554.00
CA$554.00
CA$554.00 - CA$554.00
CA$554.00
CA$1,008.00 - CA$1,008.00
CA$1,008.00
CA$1,008.00 - CA$1,008.00
CA$1,008.00

Antlia ALP-T Dual Band Ha&OIII 3nm + SII&Hb 3.5nm 2" Filter Set

ANT-ALP-T-3NM-KIT

Precise Narrowband Filtering for Exceptional Contrast Enhanced Transmission for Superior Signal-to-Noise Ratio ...

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CA$1,008.00 - CA$1,008.00
CA$1,008.00
CA$1,008.00 - CA$1,008.00
CA$1,008.00
CA$511.00 - CA$511.00
CA$511.00
CA$511.00 - CA$511.00
CA$511.00

Antlia ALP-T Dual Band SII&Hβ 3.5nm

ANT-ALP-T-3NM-SIIHB
2 in stock

Precise Narrowband Filtering for Exceptional Contrast Enhanced Transmission for Superior Signal-to-Noise Ratio Anti-Reflection Coating to Reduce H...

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CA$511.00 - CA$511.00
CA$511.00
CA$511.00 - CA$511.00
CA$511.00
CA$980.00 - CA$980.00
CA$980.00
CA$980.00 - CA$980.00
CA$980.00

Antlia ALP-T Dualband 5nm Ha/OIII and SII/Hb Filter Set - 2"

ANT-ALP-T-SET

CA$980.00 - CA$980.00
CA$980.00
CA$980.00 - CA$980.00
CA$980.00
CA$540.00 - CA$540.00
CA$540.00
CA$540.00 - CA$540.00
CA$540.00

Antlia ALP-T Dualband 5nm Ha/OIII Filter

ANT-ALP-T-2

The Antlia ALP-T dual band 5nm Ha&OIII filter is a dual line-pass filter which was designed to be used primarily with one-shot color (OSC) cam...

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CA$540.00 - CA$540.00
CA$540.00
CA$540.00 - CA$540.00
CA$540.00
CA$540.00 - CA$540.00
CA$540.00
CA$540.00 - CA$540.00
CA$540.00

Antlia ALP-T Dualband 5nm Ha/OIII Highspeed Filter

ANT-ALP-T-HS-2

ALP-T Dual Band 5nm Highspeed Filters are further optimized to work with high-speed imaging systems by shifting slightly the passband and center w...

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CA$540.00 - CA$540.00
CA$540.00
CA$540.00 - CA$540.00
CA$540.00
CA$497.00 - CA$497.00
CA$497.00
CA$497.00 - CA$497.00
CA$497.00

Antlia ALP-T Dualband 5nm SII/Hb Filter

ANT-ALP-T-SII-HB-2

The ALP-T dual band 5nm SII&Hb filter is a dual line-pass filter, which lets the deep red Sulfur-II line and the blue Hydrogen-Beta line throu...

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CA$497.00 - CA$497.00
CA$497.00
CA$497.00 - CA$497.00
CA$497.00
CA$254.00 - CA$254.00
CA$254.00
CA$254.00 - CA$254.00
CA$254.00

Antlia Triband RGB Ultra Filter V2

ANT-TRIBAND-V2
4 in stock

Enhanced Transmission for Superior Signal-to-Noise Ratio Anti-Reflection Coating to Reduce Halo Effect Optimized for Fast Optics up to f/2 Desc...

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CA$254.00 - CA$254.00
CA$254.00
CA$254.00 - CA$254.00
CA$254.00
CA$1,678.00 - CA$1,678.00
CA$1,678.00
CA$1,678.00 - CA$1,678.00
CA$1,678.00

Askar 3nm Colour Magic Ha/OIII & SII/OIII (E1+E2) Filter Package

ASK-CM-E1E2
1 in stock

Enables SHO "Hubble Palette" imaging with a one-shot-color (OSC) camera Includes two 3nm dual-bandpass filters: E1 (Hα+OIII) and E2 (SII+OIII) Iso...

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CA$1,678.00 - CA$1,678.00
CA$1,678.00
CA$1,678.00 - CA$1,678.00
CA$1,678.00
CA$847.00 - CA$847.00
CA$847.00
CA$847.00 - CA$847.00
CA$847.00

Askar 3nm Colour Magic Ultra Ha/OIII E1 Filter - 2"

ASK-ASKAR2DBE1
1 in stock

Dual-bandpass for Hydrogen-alpha (656.6nm) and Oxygen-III (500.7nm) Ultra-narrow 3.7nm (Ha) and 4.0nm (OIII) FWHM bandwidths 85% peak transmittanc...

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CA$847.00 - CA$847.00
CA$847.00
CA$847.00 - CA$847.00
CA$847.00
CA$847.00 - CA$847.00
CA$847.00
CA$847.00 - CA$847.00
CA$847.00

Askar 3nm Colour Magic Ultra OIII/SII E2 Filter - 2"

ASK-ASKAR2DBE2
1 in stock

Dual-bandpass design captures OIII (500.7nm) and SII (672nm) simultaneously Narrow 3.7nm (OIII) and 4.0nm (SII) FWHM for high-contrast imaging Pea...

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CA$847.00 - CA$847.00
CA$847.00
CA$847.00 - CA$847.00
CA$847.00
CA$875.00 - CA$875.00
CA$875.00
CA$875.00 - CA$875.00
CA$875.00

Askar 6nm Colour Magic Ha/OIII & SII/OIII (D1+D2) Filter Package

ASK-CM-D1D2
3 in stock

6nm Dual-Bandpass Filter Set Includes D1 (Hα+OIII) and D2 (SII+OIII) Filters Enables SHO-like imaging with color cameras High contrast for light-p...

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CA$875.00 - CA$875.00
CA$875.00
CA$875.00 - CA$875.00
CA$875.00
CA$447.00 - CA$447.00
CA$447.00
CA$447.00 - CA$447.00
CA$447.00

Askar 6nm Colour Magic Super Ha/OIII D1 Filter - 2"

ASK-ASK2DNHOD1
4 in stock

Dual-Bandpass: 8.5nm H-alpha & 6.5nm OIII Peak Transmittance: >85% at 500.7nm and 656.6nm Light Pollution Suppression: ≥OD5 blocking from 2...

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CA$447.00 - CA$447.00
CA$447.00
CA$447.00 - CA$447.00
CA$447.00
CA$447.00 - CA$447.00
CA$447.00
CA$447.00 - CA$447.00
CA$447.00

Askar 6nm Colour Magic Super SII/OIII D2 Filter - 2"

ASK-ASK2DNSOD2
3 in stock

Dual-band filter passing OIII (6.5nm) and SII (8.5nm) wavelengths Peak transmittance of 85% for maximum signal capture Designed for color cameras ...

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CA$447.00 - CA$447.00
CA$447.00
CA$447.00 - CA$447.00
CA$447.00
CA$315.00 - CA$315.00
CA$315.00
CA$315.00 - CA$315.00
CA$315.00

Askar Colour Magic Ha/OIII & SII/OIII (C1+C2) Filter Package

ASK-CM-C1C2
2 in stock

Complete 2-Filter Narrowband Solution for Color Cameras Captures H-alpha, Oxygen-III, and Sulfur-II Wavelengths Filter 1 (C1): Hα + OIII Duo-Band ...

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CA$315.00 - CA$315.00
CA$315.00
CA$315.00 - CA$315.00
CA$315.00

Emission Lines, Bandwidth and Focal Ratio

Narrowband filters isolate the specific wavelengths that ionized gas emits. Narrower is not always better, because the passband shifts in a fast light cone and the exposure requirement rises.

  • Hydrogen-alpha at 656.3 nm: The strongest and most widely used emission line, showing nebulosity in extraordinary detail and working well even under a bright Moon.
  • Oxygen III at 500.7 nm: Reveals planetary nebulae, supernova remnants and the outer shells of emission nebulae; typically the weakest signal of the three and needs the most integration.
  • Sulphur II at 672.4 nm: The third channel of the Hubble palette, adding structural differentiation in bright nebulae.
  • 3 to 5 nm bandwidth: Maximum contrast under light pollution, best suited to f/5 and slower systems and to accurate, temperature-compensated focus.
  • 6 to 12 nm bandwidth: More forgiving of fast optics and shorter exposures, and a better match for one-shot colour cameras and systems faster than f/4.
  • Dual and multi-band filters: Pass two or more lines simultaneously for one-shot colour cameras, giving narrowband-like contrast without a filter wheel.

Why Choose David Astro for Narrowband Filters

A filter that is wrong for your focal ratio will underperform in a way that looks like a quality problem but is a specification problem.

  • Focal ratio matched: Below roughly f/4 the incident cone shifts a narrow passband off the emission line. We recommend bandwidths or fast-optic designs that account for this.
  • Sizing to sensor and wheel geometry: We calculate the filter size needed to avoid vignetting given your sensor diagonal and filter-to-sensor distance.
  • Focus offsets explained: Narrowband channels often need per-filter focus offsets, and we help set them up so you are not refocusing manually every filter change.
  • Authorized dealer: Genuine filters with verified coatings and full manufacturer warranty, in Canadian stock.
  • Domestic shipping: No duties or brokerage fees for Canadian orders.

Narrowband Filters in Canada — Frequently Asked Questions

Can I use narrowband with a colour camera?
Yes, most effectively with a dual-band filter that passes Ha and OIII together, since a colour sensor's Bayer array can separate them. Single-line filters work but waste three quarters of the pixels.
Is a 3 nm filter always better than 7 nm?
Not in fast systems. Below about f/4 the steep light cone shifts the passband and a 3 nm filter can lose signal. In an f/6 system under city skies, 3 nm gives noticeably better contrast.
Can I image through a full Moon?
With Ha, largely yes. Moonlight is broadband scattered sunlight, and a narrow Ha filter rejects nearly all of it. OIII suffers more because its wavelength sits closer to the peak of scattered light.
How long should narrowband exposures be?
Longer than broadband — typically 300 to 600 seconds per sub, depending on focal ratio and camera read noise. Total integration for a good narrowband image is usually measured in tens of hours.

Imaging from a light-polluted site?

Tell us your telescope, camera and focal ratio and we will recommend the right bandwidths. Ships from Canada.