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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

Baader Planetarium Baader H-alpha 1.25" Bandpass Filter (20nm)
CA$137.00 - CA$241.00
CA$137.00 - CA$241.00
CA$137.00 - CA$241.00
CA$137.00

Baader Planetarium H-alpha Bandpass Filter (20nm)

Options available

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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CA$137.00 - CA$241.00
CA$137.00 - CA$241.00
CA$137.00 - CA$241.00
CA$137.00
Baader Planetarium Baader H-alpha 1.25" f/2 Highspeed-Filter (6.5nm) – CMOS-optimized
CA$233.00 - CA$571.00
CA$233.00 - CA$571.00
CA$233.00 - CA$571.00
CA$233.00

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

Options available

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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CA$233.00 - CA$571.00
CA$233.00 - CA$571.00
CA$233.00 - CA$571.00
CA$233.00
Baader Planetarium Baader H-alpha 1.25" f/2 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized
CA$431.00 - CA$1,079.00
CA$431.00 - CA$1,079.00
CA$431.00 - CA$1,079.00
CA$431.00

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

Options available

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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CA$431.00 - CA$1,079.00
CA$431.00 - CA$1,079.00
CA$431.00 - CA$1,079.00
CA$431.00
Baader Planetarium Baader H-alpha 1.25" f/3 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized
CA$417.00 - CA$934.00
CA$417.00 - CA$934.00
CA$417.00 - CA$934.00
CA$417.00

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

Options available

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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CA$417.00 - CA$934.00
CA$417.00 - CA$934.00
CA$417.00 - CA$934.00
CA$417.00
Baader Planetarium Baader H-alpha 1.25" Ultra-Narrowband-Filter (3.5nm) – CMOS-optimized
CA$415.00 - CA$932.00
CA$415.00 - CA$932.00
CA$415.00 - CA$932.00
CA$415.00

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

Options available
1 variants in stock

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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CA$415.00 - CA$932.00
CA$415.00 - CA$932.00
CA$415.00 - CA$932.00
CA$415.00
Baader Planetarium Baader H-Beta 1.25" Narrowband Filter (5.5nm) – CMOS-optimized
CA$0.00 - CA$634.00
CA$0.00 - CA$634.00
CA$0.00 - CA$634.00
CA$0.00

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

Options available

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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CA$0.00 - CA$634.00
CA$0.00 - CA$634.00
CA$0.00 - CA$634.00
CA$0.00
Baader Planetarium Baader O-III 1.25" f/2 Highspeed-Filter (6.5nm) – CMOS-optimized
CA$232.00 - CA$565.00
CA$232.00 - CA$565.00
CA$232.00 - CA$565.00
CA$232.00

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

Options available

6.5nm FWHM Bandpass for O-III Optimized for f/2 to f/3.5 High-Speed Optical Systems Available in 1.25" & 2" Mounted, 31mm, 36mm, 47.4mm (FCCT)...

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CA$232.00 - CA$565.00
CA$232.00 - CA$565.00
CA$232.00 - CA$565.00
CA$232.00
Baader Planetarium Baader O-III 1.25" f/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized
CA$395.00 - CA$829.00
CA$395.00 - CA$829.00
CA$395.00 - CA$829.00
CA$395.00

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

Options available

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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CA$395.00 - CA$829.00
CA$395.00 - CA$829.00
CA$395.00 - CA$829.00
CA$395.00
Baader Planetarium Baader O-III 1.25" f/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized
CA$383.00 - CA$823.00
CA$383.00 - CA$823.00
CA$383.00 - CA$823.00
CA$383.00

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

Options available

4nm FWHM Ultra-Narrow Bandpass Optimized for f/3 and Faster Optical Systems Available in 1.25" & 2" Mounted, 31mm, 36mm & 50.4mm Round Unm...

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CA$383.00 - CA$823.00
CA$383.00 - CA$823.00
CA$383.00 - CA$823.00
CA$383.00
Baader Planetarium O-III 1.25" Super-G Filter (9nm) - CMOS optimiert
CA$130.00 - CA$241.00
CA$130.00 - CA$241.00
CA$130.00 - CA$241.00
CA$130.00

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

Options available
1 variants in stock

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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CA$130.00 - CA$241.00
CA$130.00 - CA$241.00
CA$130.00 - CA$241.00
CA$130.00
Baader Planetarium RGB B-Filter 1.25" – CMOS-optimized
CA$136.00 - CA$398.00
CA$136.00 - CA$398.00
CA$136.00 - CA$398.00
CA$136.00

Baader Planetarium RGB B-Filter – CMOS-optimized

Options available

Available in 1.25" & 2" Mounted, Round Unmounted and Square Sizes Blue (B) Channel for LRGB Imaging Optimized for Modern CMOS Sensors Designed...

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CA$136.00 - CA$398.00
CA$136.00 - CA$398.00
CA$136.00 - CA$398.00
CA$136.00
Baader Planetarium RGB Filter Set 1.25" – CMOS-optimized
CA$370.00 - CA$1,041.00
CA$370.00 - CA$1,041.00
CA$370.00 - CA$1,041.00
CA$370.00

Baader Planetarium RGB Filter Set – CMOS-optimized

Options available

Set of three Red, Green, and Blue (RGB) filters Optimized for modern CMOS sensors to eliminate reflections Available in 1.25" & 2" mounted, 31...

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CA$370.00 - CA$1,041.00
CA$370.00 - CA$1,041.00
CA$370.00 - CA$1,041.00
CA$370.00
Baader Planetarium RGB G-Filter 1.25" – CMOS-optimized
CA$139.00 - CA$401.00
CA$139.00 - CA$401.00
CA$139.00 - CA$401.00
CA$139.00

Baader Planetarium RGB G-Filter – CMOS-optimized

Options available

Green (G) Component for LRGB Color Imaging Available in 1.25" & 2" Mounted, Round Unmounted and Square Sizes Optimized for Modern CMOS Sensors...

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CA$139.00 - CA$401.00
CA$139.00 - CA$401.00
CA$139.00 - CA$401.00
CA$139.00
Baader Planetarium RGB R-Filter 1.25" – CMOS-optimized
CA$137.00 - CA$399.00
CA$137.00 - CA$399.00
CA$137.00 - CA$399.00
CA$137.00

Baader Planetarium RGB R-Filter – CMOS-optimized

Options available

Red (R) filter for LRGB astrophotography Available in 1.25" & 2" mounted, round unmounted and square sizes Optimized for modern CMOS sensors H...

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CA$137.00 - CA$399.00
CA$137.00 - CA$399.00
CA$137.00 - CA$399.00
CA$137.00
Baader Planetarium Baader S-II 1.25" f/2 Highspeed-Filter (6.5nm) – CMOS-optimized
CA$231.00 - CA$567.00
CA$231.00 - CA$567.00
CA$231.00 - CA$567.00
CA$231.00

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

Options available

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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CA$231.00 - CA$567.00
CA$231.00 - CA$567.00
CA$231.00 - CA$567.00
CA$231.00
Baader Planetarium Baader S-II 1.25" f/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized
CA$391.00 - CA$838.00
CA$391.00 - CA$838.00
CA$391.00 - CA$838.00
CA$391.00

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

Options available

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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CA$391.00 - CA$838.00
CA$391.00 - CA$838.00
CA$391.00 - CA$838.00
CA$391.00
Baader Planetarium Baader S-II 1.25" f/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized
CA$392.00 - CA$829.00
CA$392.00 - CA$829.00
CA$392.00 - CA$829.00
CA$392.00

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

Options available

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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CA$392.00 - CA$829.00
CA$392.00 - CA$829.00
CA$392.00 - CA$829.00
CA$392.00
Baader Planetarium Baader S-II 1.25" Ultra-Narrowband-Filter (4nm) – CMOS-optimized
CA$389.00 - CA$827.00
CA$389.00 - CA$827.00
CA$389.00 - CA$827.00
CA$389.00

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

Options available
1 variants in stock

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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CA$389.00 - CA$827.00
CA$389.00 - CA$827.00
CA$389.00 - CA$827.00
CA$389.00
Baader Planetarium Baader UHC-L / Ultra-L-Booster Filter 65x65mm
CA$561.00 - CA$561.00
CA$561.00
CA$561.00 - CA$561.00
CA$561.00

Baader Planetarium UHC-L / Ultra-L-Booster Filter 65x65mm

BAA-2961566

65x65mm Unmounted Square Format Optimized for LED Light Pollution Rejection High-Contrast Views of Emission Nebulae Ideal Complement to Narrowband...

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CA$561.00 - CA$561.00
CA$561.00
CA$561.00 - CA$561.00
CA$561.00
Baader Planetarium FCCT Filter – UV/IR-Cut / L-Filter 2" unmounted (Ø 47,4 mm) – CMOS-optimized
CA$101.00 - CA$357.00
CA$101.00 - CA$357.00
CA$101.00 - CA$357.00
CA$101.00

Baader Planetarium UV/IR-Cut / L-Filter – CMOS-optimized

Options available

Serves as a high-transmission Luminance (L) filter Provides complete Ultraviolet (UV) and Infrared (IR) blocking Engineered with CMOS-optimized an...

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CA$101.00 - CA$357.00
CA$101.00 - CA$357.00
CA$101.00 - CA$357.00
CA$101.00
CA$117.00 - CA$169.00
CA$117.00 - CA$169.00
CA$117.00 - CA$169.00
CA$117.00

Baader Polarizing Filter - Double

Options available
2 variants in stock

Continuously variable brightness adjustment Available in 1.25" and 2" barrel sizes Reduces glare on the Moon and bright planets Single-unit, doubl...

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CA$117.00 - CA$169.00
CA$117.00 - CA$169.00
CA$117.00 - CA$169.00
CA$117.00
CA$62.00 - CA$105.00
CA$62.00 - CA$105.00
CA$62.00 - CA$105.00
CA$62.00

Baader Polarizing Filter - Single

Options available
1 variants in stock

Available in 1.25" and 2" Barrel Sizes Essential for Brightness Control with a Herschel Wedge Enhances Contrast on Planetary and Lunar Targets Sta...

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CA$62.00 - CA$105.00
CA$62.00 - CA$105.00
CA$62.00 - CA$105.00
CA$62.00
CA$132.00 - CA$238.00
CA$132.00 - CA$238.00
CA$132.00 - CA$238.00
CA$132.00

Baader Semi-APO Filter

Options available

Reduces chromatic aberration in achromatic refractors Enhances contrast on the Moon, planets, and bright stars Improves star sharpness by tighteni...

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CA$132.00 - CA$238.00
CA$132.00 - CA$238.00
CA$132.00 - CA$238.00
CA$132.00
CA$348.00 - CA$487.00
CA$348.00 - CA$487.00
CA$348.00 - CA$487.00
CA$348.00

Baader U-Venus Filter - 350nm

Options available

350nm Central Wavelength 60nm Bandwidth (320-380nm) ~80% Peak Transmission Blocks Visible and IR light from 200nm to 1120nm Dielectric Multi-Coate...

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CA$348.00 - CA$487.00
CA$348.00 - CA$487.00
CA$348.00 - CA$487.00
CA$348.00

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.