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.

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$255.00 USD - $490.00 USD

$255.00 USD

Antlia 3nm Narrowband H-alpha Pro Filter

Isolates the H-alpha emission line at 656.3nm 3nm bandpass (FWHM) to enhance contrast of emission targets Peak transmission greater than 88% Guara...

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$255.00 USD - $490.00 USD

$255.00 USD

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

$268.00 USD - $515.00 USD

$268.00 USD

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

Optimized for fast optical systems from f/2.6 to f/3.6 3nm bandpass (FWHM) around the H-alpha line Center wavelength pre-shifted 1.2nm to the red ...

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$268.00 USD - $515.00 USD

$268.00 USD

Antlia 3nm Narrowband H-Beta Pro Filter - 2"

$395.00 USD - $395.00 USD

$395.00 USD

$395.00 USD - $395.00 USD

$395.00 USD

Antlia 3nm Narrowband H-Beta Pro Filter - 2"

Isolates the H-Beta emission line at 486.1nm 3nm bandpass (FWHM) to enhance contrast of emission targets 88% peak transmission Greater than OD5 bl...

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$395.00 USD - $395.00 USD

$395.00 USD

$395.00 USD - $395.00 USD

$395.00 USD

Antlia 3nm Narrowband NII Pro Filter - 2"

$395.00 USD - $395.00 USD

$395.00 USD

$395.00 USD - $395.00 USD

$395.00 USD

Antlia 3nm Narrowband NII Pro Filter - 2"

Isolates the Nitrogen-II (NII) emission line at 654.8nm 3nm bandpass (FWHM) 88% peak transmission Greater than OD5 out-of-band blocking from 300-1...

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$395.00 USD - $395.00 USD

$395.00 USD

$395.00 USD - $395.00 USD

$395.00 USD

$255.00 USD - $490.00 USD

$255.00 USD

Antlia 3nm Narrowband OIII Pro Filter

3nm FWHM (Full Width at Half Maximum) Centered on the 500.7nm OIII emission line Peak transmission greater than 88% Out-of-band blocking >OD5 (...

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$255.00 USD - $490.00 USD

$255.00 USD

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

$268.00 USD - $515.00 USD

$268.00 USD

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

Optimized for f/2.6 to f/3.6 optical systems 3nm FWHM (Full Width at Half Maximum) Center wavelength pre-shifted 1.2nm to the red (501.9nm) Peak T...

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$268.00 USD - $515.00 USD

$268.00 USD

$255.00 USD - $490.00 USD

$255.00 USD

Antlia 3nm Narrowband SII Pro Filter

Isolates the Sulfur-II emission line at 672.4nm 3nm bandpass (FWHM) to enhance contrast of emission targets Peak transmission greater than 88% Usa...

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$255.00 USD - $490.00 USD

$255.00 USD

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

$263.30 USD - $506.24 USD

$263.30 USD

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

Optimized for fast optical systems from f/2.6 to f/3.6 Central wavelength pre-shifted by 1.2nm to 673.6nm to compensate for blue shift 3nm bandwid...

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$263.30 USD - $506.24 USD

$263.30 USD

$185.00 USD - $350.00 USD

$185.00 USD

Antlia 4.5nm Narrowband H-alpha Edge Filter

4.5nm Narrowband H-alpha Filter Usable down to f/3 with minimal loss of signal Peak transmission greater than 90% at 656.3nm Out-of-band blocking ...

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$185.00 USD - $350.00 USD

$185.00 USD

$185.00 USD - $350.00 USD

$185.00 USD

Antlia 4.5nm Narrowband OIII Edge Filter

4.5nm FWHM Narrowband OIII Filter Centered on the 500.7nm OIII Emission Line Peak Transmission >85% Out-of-Band Blocking >OD5 (0.001%) from ...

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$185.00 USD - $350.00 USD

$185.00 USD

$185.00 USD - $350.00 USD

$185.00 USD

Antlia 4.5nm Narrowband SII Edge Filter

Captures ionized sulfur emissions at a central wavelength (CWL) of 672.4nm Tight 4.5nm FWHM bandpass isolates faint nebulae from background skyglo...

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$185.00 USD - $350.00 USD

$185.00 USD

Antlia 7nm Narrowband H-alpha Prime Filter

$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

Antlia 7nm Narrowband H-alpha Prime Filter

7nm Full Width at Half Maximum (FWHM) Bandpass Centered on the 656.3nm Hydrogen-alpha Emission Line Passes NII Emission Lines at 654.8nm and 658.3...

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$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

Antlia 7nm Narrowband OIII Prime Filter

Isolates the 500.7nm OIII emission line 7nm FWHM bandpass for high signal capture Greater than 90% peak transmission OD4 (0.01%) out-of-band block...

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$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

Antlia 7nm Narrowband SII Prime Filter

Captures Sulfur-II emission lines at a central wavelength (CWL) of 672.4nm 7nm FWHM bandpass passes the SII lines at 671.6nm and 673.1nm Greater t...

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$158.00 USD - $158.00 USD

$158.00 USD

$158.00 USD - $158.00 USD

$158.00 USD

Antlia H-alpha 2.5nm Ultra Narrowband Filter

$465.00 USD - $590.00 USD

$465.00 USD

Antlia H-alpha 2.5nm Ultra Narrowband Filter

Isolates the H-alpha emission line at 656.3nm Ultra-narrow 2.5nm FWHM bandpass to maximize contrast Peak transmission of >=95% Deep >=OD5 (0...

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$465.00 USD - $590.00 USD

$465.00 USD

Antlia OIII 2.5nm Ultra Narrowband Filter

$465.00 USD - $590.00 USD

$465.00 USD

Antlia OIII 2.5nm Ultra Narrowband Filter

Isolates the 500.7nm Oxygen-III emission line 2.5nm (+0.3/-0.1nm) FWHM ultra-narrowband design >=92% peak transmission at the central wavelengt...

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$465.00 USD - $590.00 USD

$465.00 USD

$430.00 USD - $430.00 USD

$430.00 USD

$430.00 USD - $430.00 USD

$430.00 USD

Antlia SHO 7nm Prime Filter Set

Complete SHO narrowband filter set with a 7nm bandpass Peak transmission greater than 90% for maximum signal Out-of-band blocking of OD4 (0.01%) m...

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$430.00 USD - $430.00 USD

$430.00 USD

$430.00 USD - $430.00 USD

$430.00 USD

Antlia SII 2.5nm Ultra Narrowband Filter

$465.00 USD - $590.00 USD

$465.00 USD

Antlia SII 2.5nm Ultra Narrowband Filter

Isolates Sulfur-II emission at 671.6nm and 673.1nm Ultra-narrow 2.5nm FWHM bandpass Peak transmission of >=95% Out-of-band blocking at >=OD5...

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$465.00 USD - $590.00 USD

$465.00 USD

$484.00 USD

$484.00 USD - $484.00 USD

$484.00 USD

$363.00 USD

$363.00 USD - $363.00 USD

$363.00 USD

Astrodon H-alpha Filter - 5nm

H-α (hydrogen-alpha) at 656 nm (nanometers) is deep red in color and the most popular narrowband filter. Hydrogen is ubiquitous in the cosmos and i...

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$484.00 USD

$484.00 USD - $484.00 USD

$484.00 USD

$363.00 USD

$363.00 USD - $363.00 USD

$363.00 USD

Save 25%

$946.00 USD - $2,105.00 USD

$946.00 USD

Baader 3.5/4nm f/2 Ultra-Highspeed Filter Set - CMOS-Optimized H-alpha/O-III/S-II

3.5nm (H-alpha) and 4nm (O-III, S-II) Bandpasses Optimized for f/2 Ultra-Highspeed Optical Systems CMOS-Optimized with Reflex-Blocker™ Coatings Pr...

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$946.00 USD - $2,105.00 USD

$946.00 USD

$929.00 USD - $1,982.00 USD

$929.00 USD

Baader 3.5nm / 4nm Narrowband Filter Set - CMOS-Optimized H-alpha/O-III/S-II

3-Filter Set: H-alpha (3.5nm), O-III (4nm), S-II (4nm) Ultra-Narrow Bandpasses for Maximum Image Contrast CMOS-Optimized to Eliminate Halos and In...

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$929.00 USD - $1,982.00 USD

$929.00 USD

$320.00 USD - $692.00 USD

$320.00 USD

Baader 4nm Ultra-Narrowband OIII Filter - CMOS-Optimized

4nm Ultra-Narrowband OIII Bandpass Optimized for Modern CMOS Sensors Reflex-Blocker™ Hard Coatings to Prevent Halos Life-Coat™ Technology for Extr...

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$320.00 USD - $692.00 USD

$320.00 USD

$548.00 USD - $1,310.00 USD

$548.00 USD

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

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/3.4 High-Speed Optical Syste...

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$548.00 USD - $1,310.00 USD

$548.00 USD

$188.00 USD - $481.00 USD

$188.00 USD

Baader 6.5nm H-alpha Filter - CMOS-Optimized

6.5nm FWHM Bandpass CMOS-Optimized Anti-Reflection Coatings Reflex-Blocker™ coatings to prevent halos Life-Coat™ scratch-resistant hard coatings A...

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$188.00 USD - $481.00 USD

$188.00 USD

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.

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.

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Narrowband Filters

Filters

Emission Lines, Bandwidth and Focal Ratio

Why Choose David Astro for Narrowband Filters

Narrowband Filters in Canada: Frequently Asked Questions

Can I use narrowband with a colour camera?

Is a 3 nm filter always better than 7 nm?

Can I image through a full Moon?

How long should narrowband exposures be?

Imaging from a light-polluted site?