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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$512.00 USD - $1,287.00 USD

$512.00 USD

Baader 6.5nm Narrowband Filter Set - CMOS-Optimized H-alpha/O-III/S-II

6.5nm Narrowband Filter Set for H-alpha, O-III, and S-II Optimized specifically for modern CMOS astronomy cameras Reflex-Blocker™ coatings prevent...

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$512.00 USD - $1,287.00 USD

$512.00 USD

$179.00 USD - $470.00 USD

$179.00 USD

Baader 6.5nm OIII Filter - CMOS-Optimized

6.5nm FWHM Bandpass Optimized for Modern CMOS Sensors Reflex-Blocker™ Hard Coatings Available in 7 Formats (Mounted and Unmounted) Plane-Parallel ...

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$179.00 USD - $470.00 USD

$179.00 USD

$176.00 USD - $468.00 USD

$176.00 USD

Baader 6.5nm SII Filter - CMOS-Optimized

6.5nm FWHM Bandpass Optimized for Modern CMOS Sensors Suppresses Halos and Internal Reflections High-Contrast for Sulfur-II Emission Nebulae Avail...

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$176.00 USD - $468.00 USD

$176.00 USD

Baader Planetarium Baader 3.5 / 4nm f/3 Ultra-Highspeed Filter-Set 1.25" – CMOS-optimized (H-alpha / O-III / S-II)

$929.00 USD - $1,971.00 USD

$929.00 USD

Baader Planetarium 3.5 / 4nm f/3 Ultra-Highspeed Filter-Set – CMOS-optimized (H-alpha / O-III / S-II)

3.5 / 4nm Ultra-Narrow H-alpha, O-III & S-II Bandpasses Pre-Shifted for Fast f/3 "Ultra-Highspeed" Optical Systems CMOS-Optimized with Anti-Re...

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$929.00 USD - $1,971.00 USD

$929.00 USD

Baader Planetarium Baader H-alpha 1.25" Bandpass Filter (20nm)

$115.00 USD - $201.00 USD

$115.00 USD

Baader Planetarium H-alpha Bandpass Filter (20nm)

H-alpha Bandpass Filter in 1.25" & 2" Sizes 20nm FWHM Bandwidth 656.3nm Center Wavelength Optimized for Color CMOS/CCD Cameras High-Contrast f...

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$115.00 USD - $201.00 USD

$115.00 USD

Baader Planetarium Baader H-alpha 1.25" f/2 Highspeed-Filter (6.5nm) – CMOS-optimized

$199.00 USD - $487.00 USD

$199.00 USD

Baader Planetarium H-alpha f/2 Highspeed-Filter (6.5nm) – CMOS-optimized

Engineered for ultra-fast f/2 optical systems 6.5nm H-alpha bandpass for high-contrast imaging CMOS-optimized to suppress halos and internal refle...

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$199.00 USD - $487.00 USD

$199.00 USD

Baader Planetarium Baader H-alpha 1.25" f/2 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized

$363.00 USD - $873.00 USD

$363.00 USD

Baader Planetarium H-alpha f/2 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized

Engineered for f/2 ultra-highspeed optical systems 3.5nm bandpass for maximum H-alpha contrast CMOS-optimized with anti-reflection coatings Availa...

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$363.00 USD - $873.00 USD

$363.00 USD

Baader Planetarium Baader H-alpha 1.25" f/3 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized

$347.00 USD - $770.00 USD

$347.00 USD

Baader Planetarium H-alpha f/3 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized

3.5nm H-alpha Bandpass Optimized for f/3 Ultra-High-Speed Systems Available in 1.25" & 2" mounted, 31mm, 36mm & 50.4mm round unmounted, an...

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$347.00 USD - $770.00 USD

$347.00 USD

Baader Planetarium Baader H-alpha 1.25" Ultra-Narrowband-Filter (3.5nm) – CMOS-optimized

$352.00 USD - $795.00 USD

$352.00 USD

Baader Planetarium H-alpha Ultra-Narrowband-Filter (3.5nm) – CMOS-optimized

3.5nm Ultra-Narrow Bandpass Available in 1.25" & 2" mounted, 31mm, 36mm & 50.4mm round unmounted, and 50x50mm & 65x65mm square sizes C...

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$352.00 USD - $795.00 USD

$352.00 USD

Baader Planetarium Baader H-Beta 1.25" Narrowband Filter (5.5nm) – CMOS-optimized

$244.00 USD - $559.00 USD

$244.00 USD

Baader Planetarium H-Beta Narrowband-Filter (5.5nm) – CMOS-optimized

Isolates Hydrogen-Beta (H-Beta) Emission Line 5.5nm FWHM Narrowband Passband Available in 1.25" & 2" Mounted, 31/36/50.4mm Round Unmounted and...

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$244.00 USD - $559.00 USD

$244.00 USD

Baader Planetarium Baader O-III 1.25" f/2 Highspeed-Filter (6.5nm) – CMOS-optimized

$199.00 USD - $479.00 USD

$199.00 USD

Baader Planetarium O-III f/2 Highspeed-Filter (6.5nm) – CMOS-optimized

6.5nm FWHM Bandpass for O-III Optimized for f/3.4 and Faster High-Speed Optical Systems Available in 1.25" & 2" Mounted, 31mm, 36mm, 47.4mm (F...

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$199.00 USD - $479.00 USD

$199.00 USD

Baader Planetarium Baader O-III 1.25" f/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

$333.00 USD - $669.00 USD

$333.00 USD

Baader Planetarium O-III f/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

4nm FWHM Bandpass Optimized for f/2 Ultra-Highspeed Systems Available in 1.25" & 2" Mounted, 31mm, 36mm, 47.4mm (FCCT) & 50.4mm Round Unmo...

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$333.00 USD - $669.00 USD

$333.00 USD

Baader Planetarium Baader O-III 1.25" f/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

$317.00 USD - $667.00 USD

$317.00 USD

Baader Planetarium O-III f/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

4nm FWHM Ultra-Narrow Bandpass Optimized for f/3.4 to f/2.3 Optical Systems Available in 1.25" & 2" Mounted, 31mm, 36mm & 50.4mm Round Unm...

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$317.00 USD - $667.00 USD

$317.00 USD

Baader Planetarium O-III 1.25" Super-G Filter (9nm) - CMOS optimiert

$108.00 USD - $200.00 USD

$108.00 USD

Baader Planetarium O-III Super-G Filter (9nm) – CMOS-optimized

9nm O-III Narrowband Passband Functions as a "Super-G" Green Filter Replacement CMOS-Optimized Coatings for High Contrast Reduces Impact of Atmosp...

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$108.00 USD - $200.00 USD

$108.00 USD

Baader Planetarium Baader S-II 1.25" f/2 Highspeed-Filter (6.5nm) – CMOS-optimized

$195.00 USD - $475.00 USD

$195.00 USD

Baader Planetarium S-II f/2 Highspeed-Filter (6.5nm) – CMOS-optimized

6.5nm Sulfur-II Narrowband Filter Optimized for f/2 High-Speed Optical Systems Available in 1.25" & 2" Mounted, 31mm, 36mm, 50.4mm & 2" FC...

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$195.00 USD - $475.00 USD

$195.00 USD

Baader Planetarium Baader S-II 1.25" f/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

$324.00 USD - $671.00 USD

$324.00 USD

Baader Planetarium S-II f/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

4nm FWHM Bandpass for Sulfur-II (S-II) Engineered for f/2 Ultra-Highspeed Optical Systems Available in 1.25" & 2" Mounted, 31mm, 36mm, 50.4mm ...

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$324.00 USD - $671.00 USD

$324.00 USD

Baader Planetarium Baader S-II 1.25" f/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

$324.00 USD - $660.00 USD

$324.00 USD

Baader Planetarium S-II f/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized

4nm Bandwidth (FWHM) Pre-Shifted for Fast f/3 Optical Systems Available in 1.25" & 2" Mounted, 31mm, 36mm & 50.4mm Unmounted Round, and 50...

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$324.00 USD - $660.00 USD

$324.00 USD

Baader Planetarium Baader S-II 1.25" Ultra-Narrowband-Filter (4nm) – CMOS-optimized

$324.00 USD - $694.00 USD

$324.00 USD

Baader Planetarium S-II Ultra-Narrowband-Filter (4nm) – CMOS-optimized

4nm Full-Width Half-Maximum (FWHM) Bandpass Optimized for Modern CMOS Sensors Available in 1.25" (M28.5 x 0.6) & 2" Mounted, 31mm, 36mm & ...

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$324.00 USD - $694.00 USD

$324.00 USD

$575.00 USD - $1,550.00 USD

$575.00 USD

Chroma H-alpha Filter - 3nm

Isolates the 656.3 nm Hydrogen-alpha emission line 3 nm bandpass for high contrast against skyglow and light pollution Designed for imaging system...

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$575.00 USD - $1,550.00 USD

$575.00 USD

$460.00 USD - $1,380.00 USD

$460.00 USD

Chroma H-alpha Filter - 5nm

5nm Bandwidth (FWHM) Centered on the 656.3 nm H-alpha Emission Line Designed for f/4.0 or Slower Telescopes 3.0 mm Thick Parfocal Substrate Transm...

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$460.00 USD - $1,380.00 USD

$460.00 USD

$275.00 USD - $830.00 USD

$275.00 USD

Chroma H-alpha Filter - 8nm

8nm Bandwidth (FWHM) Centered on 656.3 nm H-alpha Line 3.0 mm Parfocal Substrate Durable Sputtered Hard Coatings Transmitted Wavefront Better Than...

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$275.00 USD - $830.00 USD

$275.00 USD

$575.00 USD - $1,550.00 USD

$575.00 USD

Chroma H-alpha Filter Optimized for f/3 - 3nm

Isolates the 656.3 nm Hydrogen-alpha emission line 3 nm bandpass for maximum contrast Optimized for f/2.8 to f/3.6 optical systems Peak transmissi...

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$575.00 USD - $1,550.00 USD

$575.00 USD

$575.00 USD - $1,550.00 USD

$575.00 USD

Chroma H-beta Filter - 3nm

Isolates the Hydrogen-beta emission line at 486.1 nm Narrow 3 nm bandpass for high contrast Designed for f/4.0 or slower optical systems 3.0 mm th...

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$575.00 USD - $1,550.00 USD

$575.00 USD

$460.00 USD - $1,380.00 USD

$460.00 USD

Chroma H-beta Filter - 5nm

Central Wavelength: 486.1 nm (Hydrogen-beta) Bandwidth: 5 nm FWHM Glass Thickness: 3.0 mm Parfocal with other Chroma astronomy filters (except LoG...

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$460.00 USD - $1,380.00 USD

$460.00 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?