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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

Explore Scientific Nebula Filter S-II 2-inch 12nm
CA$350.00 - CA$350.00
CA$350.00
CA$350.00 - CA$350.00
CA$350.00

Explore Scientific Nebula Filter S-II 2-inch 12nm

ES-310110

Isolates the 672nm Sulfur-II (S-II) emission line 12nm bandpass for high-contrast views 2-inch filter size with standard threads Blocks light poll...

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CA$350.00 - CA$350.00
CA$350.00
CA$350.00 - CA$350.00
CA$350.00
Explore Scientific Nebula Filter S-II 2-inch 6.5nm
CA$420.00 - CA$420.00
CA$420.00
CA$420.00 - CA$420.00
CA$420.00

Explore Scientific Nebula Filter S-II 2-inch 6.5nm

ES-310120

6.5nm Narrow Bandpass Targets the 672nm Ionized Sulfur (S-II) Emission Line 2-inch Barrel Diameter for Larger Focusers Drastically Increases Contr...

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CA$420.00 - CA$420.00
CA$420.00
CA$420.00 - CA$420.00
CA$420.00
CA$418.00 - CA$418.00
CA$418.00
CA$418.00 - CA$418.00
CA$418.00

IDAS NBZ-II HA OIII Nebula Booster Filter

IDA-NBZ-II-48ST2

2" OIII 8nm (+/-0.4nm) H-alpha 9.5nm (+/- 0.4nm) (originally designed at 10nm, but on a measured basis, it's 9.5nm.)

CA$418.00 - CA$418.00
CA$418.00
CA$418.00 - CA$418.00
CA$418.00
CA$474.00 - CA$586.00
CA$474.00 - CA$586.00
CA$474.00 - CA$586.00
CA$474.00

Optolong H-alpha 3nm Narrowband Filter

Options available
1 variants in stock

3nm Bandpass at 656nm Wavelength Maximizes Contrast for Emission Nebulae Extreme Rejection of Light Pollution and Skyglow Ion-Assisted, Anti-Refle...

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CA$474.00 - CA$586.00
CA$474.00 - CA$586.00
CA$474.00 - CA$586.00
CA$474.00
Optolong H-Alpha 7nm Narrowband Filter
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00

Optolong H-Alpha 7nm Narrowband Filter

Options available
3 variants in stock

Isolates the 656nm Hydrogen-alpha emission line 7nm bandpass for maximum contrast Blocks mercury vapor, sodium vapor, and natural skyglow Ideal fo...

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CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00
Optolong Ha 7nm, OIII 6.5nm & SII 6.5nm Filter Set
CA$651.00 - CA$937.00
CA$651.00 - CA$937.00
CA$651.00 - CA$937.00
CA$651.00

Optolong Ha 7nm, OIII 6.5nm & SII 6.5nm Filter Set

Options available

H-alpha Filter: 7nm Bandpass centered at 656nm Oxygen-III Filter: 6.5nm Bandpass centered at 500nm Sulphur-II Filter: 6.5nm Bandpass Hubble Pa...

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CA$651.00 - CA$937.00
CA$651.00 - CA$937.00
CA$651.00 - CA$937.00
CA$651.00
Optolong Ha, OIII & SII 3nm Narrowband Filter Set
CA$1,344.00 - CA$1,679.00
CA$1,344.00 - CA$1,679.00
CA$1,344.00 - CA$1,679.00
CA$1,344.00

Optolong Ha, OIII & SII 3nm Narrowband Filter Set

Options available

Complete SHO set includes H-alpha, OIII, and SII filters Ultra-narrow 3nm bandpass for maximum contrast Isolates 656nm Ha and 500nm OIII emission ...

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CA$1,344.00 - CA$1,679.00
CA$1,344.00 - CA$1,679.00
CA$1,344.00 - CA$1,679.00
CA$1,344.00
CA$251.00 - CA$363.00
CA$251.00 - CA$363.00
CA$251.00 - CA$363.00
CA$251.00

Optolong L-Enhance Filter

Options available
7 variants in stock

Dual-bandpass filter isolates H-Alpha, H-Beta, and OIII emission lines Peak transmission of over 90% for maximum signal Blocks over 99% of light p...

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CA$251.00 - CA$363.00
CA$251.00 - CA$363.00
CA$251.00 - CA$363.00
CA$251.00
CA$796.00 - CA$796.00
CA$796.00
CA$796.00 - CA$796.00
CA$796.00

Optolong L-Extreme + L-Synergy L2 Dual-Combo Filter Set - 2"

OPT-L2-COMBO
3 in stock

Includes L-eXtreme (H-alpha + OIII) and L-Synergy (SII + OIII) filters Enables Hubble Palette (SHO) imaging with one-shot color cameras Captures t...

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CA$796.00 - CA$796.00
CA$796.00
CA$796.00 - CA$796.00
CA$796.00
CA$335.00 - CA$432.00
CA$335.00 - CA$432.00
CA$335.00 - CA$432.00
CA$335.00

Optolong L-Extreme Filter

Options available
9 variants in stock

Narrow dual-bandpass filter for H-Alpha and OIII Blocks >99% of light pollution emission lines Peak transmission of >90% at critical wavelen...

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CA$335.00 - CA$432.00
CA$335.00 - CA$432.00
CA$335.00 - CA$432.00
CA$335.00
CA$362.00 - CA$362.00
CA$362.00
CA$362.00 - CA$362.00
CA$362.00

Optolong L-Para HA/OIII 10nm Filter - 2"

OPT-AS100221
5 in stock

Dual Narrowband H-Alpha & OIII Filter Suppresses Mercury, Sodium & LED Light Pollution Optimized for Fast-Ratio Systems (RASA, HyperStar) ...

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CA$362.00 - CA$362.00
CA$362.00
CA$362.00 - CA$362.00
CA$362.00
CA$558.00 - CA$558.00
CA$558.00
CA$558.00 - CA$558.00
CA$558.00

Optolong L-Quad Enhance + L-Para L1 Dual-Combo Filter Set - 2"

OPT-L1-SET
4 in stock

L-Quad Enhance Filter: A quad-bandpass filter designed for balanced RGB color from broadband targets. L-Para L1 Filter: A dual-narrowband filter...

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CA$558.00 - CA$558.00
CA$558.00
CA$558.00 - CA$558.00
CA$558.00
CA$278.00 - CA$278.00
CA$278.00
CA$278.00 - CA$278.00
CA$278.00

Optolong L-Quad Enhance Filter

OPT-14702
4 in stock

Quad-bandpass design for color cameras Suppresses light pollution with OD2-OD4 blocking depth Maintains sharpness with a λ/4 transmitted wavefront...

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CA$278.00 - CA$278.00
CA$278.00
CA$278.00 - CA$278.00
CA$278.00
CA$432.00 - CA$432.00
CA$432.00
CA$432.00 - CA$432.00
CA$432.00

Optolong L-Synergy 7nm SII/OIII Dual Narrowband Filter

OPT-LSYNERGY
3 in stock

Captures Sulfur-II and Oxygen-III Emission Lines Simultaneously Engineered for Hubble Palette (SHO) Imaging with Color Cameras Strict 7nm Bandpass...

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CA$432.00 - CA$432.00
CA$432.00
CA$432.00 - CA$432.00
CA$432.00
CA$404.00 - CA$545.00
CA$404.00 - CA$545.00
CA$404.00 - CA$545.00
CA$404.00

Optolong L-Ultimate Ha/OIII 3nm Filter

Options available
14 variants in stock

Dual 3nm bandpass isolates Hydrogen-alpha and Oxygen-III emission lines Blocks light pollution across the 300-1000nm spectrum Greater than OD4 blo...

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CA$404.00 - CA$545.00
CA$404.00 - CA$545.00
CA$404.00 - CA$545.00
CA$404.00
CA$517.00 - CA$797.00
CA$517.00 - CA$797.00
CA$517.00 - CA$797.00
CA$517.00

Optolong LRGB + H-Alpha 7nm Filter Set

Options available

Complete 5-Filter LRGB and H-Alpha Set 7nm H-Alpha Filter Centered at 656.3nm Blocks 589nm Sodium Light Pollution Line High Transmission for Natur...

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CA$517.00 - CA$797.00
CA$517.00 - CA$797.00
CA$517.00 - CA$797.00
CA$517.00
Optolong OIII 3nm Narrowband Filter
CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00

Optolong OIII 3nm Narrowband Filter

Options available
1 variants in stock

3nm Spectral Bandpass 500nm Central Wavelength (OIII) Ion-Assisted Multi-Layer Coatings Optimized for Monochrome Cameras Available in 2" Mounted o...

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CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00
Optolong OIII 6.5nm Narrowband Filter
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00

Optolong OIII 6.5nm Narrowband Filter

Options available
3 variants in stock

6.5nm Narrowband OIII Filter Centered on 500nm Wavelength Captures both 495.9nm and 500.7nm Emission Lines Blocks Light Pollution and Skyglow Idea...

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CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00
Optolong SII 3nm Narrowband Filter
CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00

Optolong SII 3nm Narrowband Filter

Options available
1 variants in stock

Isolates the Sulfur-II (SII) emission line for astrophotography Extremely narrow 3nm bandpass for maximum contrast Drastically reduces skyglow and...

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CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00 - CA$587.00
CA$475.00
Optolong SII 6.5nm Narrowband Filter
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00

Optolong SII 6.5nm Narrowband Filter

Options available
3 variants in stock

Isolates the Sulfur-II (SII) emission line at 672nm Tight 6.5nm bandpass for maximum contrast Enables imaging in heavily light-polluted skies and ...

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CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00 - CA$321.00
CA$223.00
Player One Anti-Halo PRO Dual-Band 2″ Ha+OIII filter
CA$699.00 - CA$699.00
CA$699.00
CA$699.00 - CA$699.00
CA$699.00

Player One Anti-Halo PRO Dual-Band Ha/OIII Filter - 2"

POA-AHP-HO-2

Advanced Halo Suppression: Specifically engineered to eliminate halos around even the brightest stars. Dual-Band Ha+OIII Design: Captures hydrog...

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CA$699.00 - CA$699.00
CA$699.00
CA$699.00 - CA$699.00
CA$699.00
Player One Ha 7nm Narrowband Filter S-series – 2"
Player One Ha 7nm Narrowband Filter S-series – 1.25"
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00

Player One Ha 7nm Narrowband Filter S-series

Options available

7nm Hydrogen-alpha (Ha) Narrowband Filter Available in 1.25" Threaded Cell and 2" Round Mounted Formats Optimized for Monochrome CMOS/CCD Cameras ...

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CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00
Player One OIII 7nm Narrowband Filter S-series – 2"
Player One OIII 7nm Narrowband Filter S-series – 1.25"
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00

Player One OIII 7nm Narrowband Filter S-series

Options available

Oxygen-III (OIII) 7nm Narrowband Filter Available in 1.25" and 2" Sizes for Narrowband Astrophotography High-Transmission, Multi-Layer Coatings Hi...

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CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00
Player One SII 7nm Narrowband Filter S-series – 2"
Player One SII 7nm Narrowband Filter S-series – 1.25"
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00

Player One SII 7nm Narrowband Filter S-series

Options available

Sulfur-II (SII) Narrowband Filter 7nm Narrowband Passband Available in 1.25" and 2" Mounted Formats Optimized for High-Contrast Astrophotography A...

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CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00

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.