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Filters

A filter decides what light reaches your sensor or your eye, and under Canadian suburban skies that decision often matters more than aperture. The right narrowband filter can make a nebula imageable from a driveway that visually shows almost nothing. David Astro carries filters in Canada — narrowband, LRGB, light pollution, planetary, solar and scientific — in 1.25", 2", 31 mm, 36 mm and unmounted formats, shipped from Canadian stock.

Filter selection is where our team spends a lot of time, because bandwidth, f-ratio and sensor size interact in ways that are not obvious from a product page. Tell us your telescope and camera and we will recommend a set that works together.

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$236.00 - CA$236.00
CA$236.00
CA$236.00 - CA$236.00
CA$236.00

Antlia CH4 Methane Filter - 1.25"

ANT-CH4
1 in stock

Antlia methane (CH4) filter is a specialized filter that allows light in the near infrared portion of the spectrum centered at 889nm to pass throug...

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CA$236.00 - CA$236.00
CA$236.00
CA$236.00 - CA$236.00
CA$236.00
CA$141.00 - CA$141.00
CA$141.00
CA$141.00 - CA$141.00
CA$141.00

Antlia H-beta and OIII Visual Filter - 1.25"

ANT-HB-OIII-1.25
3 in stock

Antlia HB-OIII filter is engineered specifically for night visual nebulae observation at a high contrast and Deep-sky astrophotography. Its transm...

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CA$141.00 - CA$141.00
CA$141.00
CA$141.00 - CA$141.00
CA$141.00
CA$55.00 - CA$55.00
CA$55.00
CA$55.00 - CA$55.00
CA$55.00

Antlia IR Pass 685nm Filter - 1.25"

ANT-IR685
3 in stock

The Antlia IR Pass 685nm filter is an absorptive filter that allows infrared light with wavelengths of more than 685nm to pass through. At these l...

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CA$55.00 - CA$55.00
CA$55.00
CA$55.00 - CA$55.00
CA$55.00
CA$55.00 - CA$55.00
CA$55.00
CA$55.00 - CA$55.00
CA$55.00

Antlia IR Pass 850nm Filter - 1.25"

ANT-IR850
3 in stock

The Antlia IR Pass 850nm filter is an absorptive filter that allows infrared light with wavelengths of more than 850nm to pass through. It is a su...

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CA$55.00 - CA$55.00
CA$55.00
CA$55.00 - CA$55.00
CA$55.00
CA$426.00 - CA$852.00
CA$426.00 - CA$852.00
CA$426.00 - CA$852.00
CA$426.00

Antlia LRGB-V Pro Filter Set

Options available
8 variants in stock

Four-Filter LRGB Complement Engineered for Monochrome CMOS/CCD Cameras Anti-Reflection Coated Optics Available in 5 Mounted and Unmounted Sizes ...

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CA$426.00 - CA$852.00
CA$426.00 - CA$852.00
CA$426.00 - CA$852.00
CA$426.00
CA$281.00 - CA$281.00
CA$281.00
CA$281.00 - CA$281.00
CA$281.00

Antlia Quad Band Light Pollution Filter - 2"

ANT-QUAD-2
5 in stock

The Antlia Quad Band Anti-Light Pollution Filter is a light suppression filter for color and monochrome cameras. It is able to shoot most deep sky...

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CA$281.00 - CA$281.00
CA$281.00
CA$281.00 - CA$281.00
CA$281.00
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$283.00 - CA$283.00
CA$283.00
CA$283.00 - CA$283.00
CA$283.00

Antlia U-Venus Filter - 1.25"

ANT-UVENUS
2 in stock

Antlia Venus-U filter is designed for imaging the cloud structure of Venus and Jupiter with CCD cameras on a telescope. Cloud details primarily re...

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CA$283.00 - CA$283.00
CA$283.00
CA$283.00 - CA$283.00
CA$283.00

Filter Types and When Each One Earns Its Place

Filters do not add signal. They remove unwanted light so that the signal you want has better contrast against the background. Choosing well means knowing which unwanted light you are fighting.

  • Narrowband filters: Ha, OIII and SII passbands, typically 3 to 12 nm. Narrower bands reject more light pollution and moonlight but demand accurate focus and longer exposures.
  • LRGB filter sets: Parfocal luminance, red, green and blue for colour imaging with monochrome sensors, with the luminance channel carrying most of the detail.
  • Light pollution filters: Broadband rejection of mercury and sodium emission lines. Effective against older street lighting and much less effective against broad-spectrum LED.
  • Planetary and colour filters: Wratten-standard colour filters that raise contrast on specific planetary features — a red or orange filter on Mars, blue on Jupiter's belts.
  • Solar filters: Full-aperture white-light filters for safe observation of sunspots and transits.
  • Neutral density and polarizing: Variable brightness reduction for lunar observing without altering colour balance.

Why Choose David Astro for Filters

A filter that performs beautifully at f/7 can produce a shifted passband and soft results at f/3. That is the kind of detail worth asking about before ordering.

  • F-ratio matched recommendations: Narrowband passbands shift blueward in fast optical systems, so we recommend filters specified for your focal ratio rather than the narrowest available.
  • Sensor size and vignetting: We size filters to your sensor diagonal and filter wheel placement, so an undersized filter does not clip your corners.
  • Spacing accounted for: Filter glass shifts focus by roughly a third of its thickness, and we include that in the back-focus calculation we provide.
  • Authorized dealer: Genuine filters with full manufacturer warranty and verified coatings, in Canadian inventory and shipped domestically.
  • Ships from Canada: No duties or brokerage charges for Canadian buyers.

Filters in Canada — Frequently Asked Questions

Do light pollution filters still work under LED streetlights?
Much less well than they did under sodium lighting. LED emits across a broad spectrum, so there is no narrow band to reject. Narrowband filters remain effective because they pass only emission lines regardless of what the streetlight does.
How narrow should my Ha filter be?
For f/5 and slower, 3 to 5 nm gives excellent contrast. Below about f/4, the incident light cone shifts the passband and a 6 to 7 nm filter, or one specified for fast optics, performs better.
What size filters do I need?
Match the sensor diagonal plus the distance from filter to sensor. A 36 mm filter typically covers APS-C in a standard wheel; full frame usually needs 50 mm square or unmounted 2 inch.
Are filters shipped from Canada?
Yes, in-stock filters are held in our Canadian warehouse and reach Canadian customers without customs handling.

Building a filter set?

Tell us your telescope, camera and sky conditions and we will recommend the right bandwidths and sizes. Canadian stock, fast domestic shipping.