Skip to content
Closed October 10–12 for Thanksgiving weekend
Closed October 10–12 for Thanksgiving weekend

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$660.00 - CA$660.00
CA$660.00
CA$660.00 - CA$660.00
CA$660.00

William Optics STC Astro Duo-Narrowband Filter

WO-YF-STC-ADN

Dual-Bandpass for H-Alpha and Oxygen-III Suppresses Urban Light Pollution Ion Beam-Assisted Deposition (IBAD) Coatings High Durability and Easy-to...

View full details
CA$660.00 - CA$660.00
CA$660.00
CA$660.00 - CA$660.00
CA$660.00
CA$328.00 - CA$328.00
CA$328.00
CA$328.00 - CA$328.00
CA$328.00

William Optics STC Ultra Layer Astro Multispectra Filter - 48mm

WO-YF-STC-M48

48mm (M48) Filter Size Multi-Bandpass Light Pollution Suppression Passes H-α, H-β, and OIII Emission Lines Schott B270 Optical Glass Substrate STC...

View full details
CA$328.00 - CA$328.00
CA$328.00
CA$328.00 - CA$328.00
CA$328.00
CA$22.00 - CA$22.00
CA$22.00
CA$22.00 - CA$22.00
CA$22.00

ZWO 2" to 1.25" Filter Adapter Ring

ZWO-2-1.25FL
7 in stock

Adapts 1.25" mounted filters for use in 2" filter holders Compatible with ZWO 5-position and 7-position 2" filter wheels Fits ZWO M42 and M54 filt...

View full details
CA$22.00 - CA$22.00
CA$22.00
CA$22.00 - CA$22.00
CA$22.00
CA$26.00 - CA$69.00
CA$26.00 - CA$69.00
CA$26.00 - CA$69.00
CA$26.00

ZWO AR Protective Window

Options available
5 variants in stock

Protects camera sensor from dust and humidity 21mm diameter for specific ZWO camera models High-transmission Anti-Reflection (AR) coatings 1/4λ su...

View full details
CA$26.00 - CA$69.00
CA$26.00 - CA$69.00
CA$26.00 - CA$69.00
CA$26.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00

ZWO CH4 Methane Filter - 20nm 1.25"

ZWO-CH4
3 in stock

Reveals high-altitude detail on Jupiter and Saturn 20nm bandpass centered on the methane absorption line Standard 1.25" (31.75mm) threaded cell Re...

View full details
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$239.00
CA$139.00 - CA$239.00
CA$139.00 - CA$239.00
CA$139.00

ZWO Duo-Band Filter

Options available
7 variants in stock

Passes H-Alpha (15nm) and OIII (35nm) Wavelengths Designed for One-Shot Color (OSC) Cameras 1.25" Threaded Cell Over 80% Ha & 90% OIII Transmi...

View full details
CA$139.00 - CA$239.00
CA$139.00 - CA$239.00
CA$139.00 - CA$239.00
CA$139.00
CA$849.00 - CA$849.00
CA$849.00
CA$849.00 - CA$849.00
CA$849.00

ZWO EFW - 7 x 50mm Square Filter Wheel

ZWO EFW-7x50

Holds seven 50mm square unmounted filters Designed for large-format sensors like the ZWO ASI461MM Pro Direct bolt-on connection for maximum rigidi...

View full details
CA$849.00 - CA$849.00
CA$849.00
CA$849.00 - CA$849.00
CA$849.00
CA$335.00 - CA$335.00
CA$335.00
CA$335.00 - CA$335.00
CA$335.00

ZWO EFW - 8 x 1.25" or 31mm

ZWO-EFW-8x1.25
Only 1 left!

For 1.25" or 31mm filters Easy to install on the telescope and the camera Filters are easy to ins...

View full details
CA$335.00 - CA$335.00
CA$335.00
CA$335.00 - CA$335.00
CA$335.00
CA$279.00 - CA$279.00
CA$279.00
CA$279.00 - CA$279.00
CA$279.00

ZWO Electronic Filter Wheel EFW Gen2 - 5 x 1.25"

ZWO-EFW-5x1.25-25
3 in stock

5 filter positions for 1.25" or 31mm filters Adds 20 mm of back focus to the imaging train USB-C powered and controlled Redesigned housing for imp...

View full details
CA$279.00 - CA$279.00
CA$279.00
CA$279.00 - CA$279.00
CA$279.00
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00

ZWO Electronic Filter Wheel EFW Gen2 - 5 x 2"

ZWO-EFW-5x2-25
5 in stock

Holds 5 x 2" mounted or 50mm unmounted filters Adds only 20 mm of back focus to the imaging train Stepper motor for precise, repeatable filter sel...

View full details
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00
CA$559.00 - CA$559.00
CA$559.00
CA$559.00 - CA$559.00
CA$559.00

ZWO Electronic Filter Wheel EFW Gen2 - 7 x 2"

ZWO-EFW-7x2-25
1 in stock

Holds seven 2" mounted or 50mm unmounted filters Adds 20 mm of back focus to the imaging train Stepper motor for precise, quiet filter selection S...

View full details
CA$559.00 - CA$559.00
CA$559.00
CA$559.00 - CA$559.00
CA$559.00
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00

ZWO Electronic Filter Wheel EFW Gen2 - 7 x 36mm

ZWO-EFW-7x36-25
2 in stock

Houses seven 36mm unmounted filters Adds a minimal 20mm of back focus to the imaging train 7-position carousel for LRGB, narrowband, or custom set...

View full details
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00

ZWO Electronic Filter Wheel EFW Gen2 - 8 x 1.25"

ZWO-EFW-8x1.25-25
5 in stock

Holds 8 x 1.25" mounted or 31mm unmounted filters Adds 20 mm of back focus to the imaging train USB-powered stepper motor for precise filter selec...

View full details
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00

ZWO Filter Drawer for EOS Lens

ZWO-FD-EOS
10 in stock

Connects Canon EOS lenses to ZWO ASI cameras Accepts standard 2" mounted filters Magnetic holder for secure, fast filter changes Adds 26.5mm of op...

View full details
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00

ZWO Filter Drawer for Nikon Lens

ZWO-FD-NIKON
10 in stock

Adapts Nikon lenses to ZWO ASI cooled cameras Accepts standard 2-inch (M48x0.75 thread) mounted filters Ultra-thin 29 mm profile maintains focus I...

View full details
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
CA$111.00 - CA$111.00
CA$111.00
CA$111.00 - CA$111.00
CA$111.00

ZWO Filter Drawer V2 - M42

ZWO-FD-M42-II
47 in stock

Accepts standard 2-inch mounted filters Adds a precise 21mm to the optical path M42 x 0.75 male threads on the camera side M48 x 0.75 female threa...

View full details
CA$111.00 - CA$111.00
CA$111.00
CA$111.00 - CA$111.00
CA$111.00
CA$111.00 - CA$111.00
CA$111.00
CA$111.00 - CA$111.00
CA$111.00

ZWO Filter Drawer V2 - M54

ZWO-FD-M54-II
20 in stock

Connects to M54 x 0.75 threaded accessories Accepts standard 2" mounted filters Magnetic holder for quick filter changes Adjustable tension screw ...

View full details
CA$111.00 - CA$111.00
CA$111.00
CA$111.00 - CA$111.00
CA$111.00
CA$49.00 - CA$49.00
CA$49.00
CA$49.00 - CA$49.00
CA$49.00

ZWO Filter Holder V2

ZWO-F-HLDR
27 in stock

Holds standard 2-inch (50.8mm) mounted filters M48x0.75 internal threads for secure filter mounting Enables pre-loading multiple filters for rapid...

View full details
CA$49.00 - CA$49.00
CA$49.00
CA$49.00 - CA$49.00
CA$49.00
CA$17.00 - CA$21.00
CA$17.00 - CA$21.00
CA$17.00 - CA$21.00
CA$17.00

ZWO Filter Masks

Options available
5 variants in stock

Securely Mounts 36mm Unmounted Filters Compatible with All 7-Position ZWO 36mm EFWs Includes M2 Mounting Screws Prevents Internal Light Leaks D...

View full details
CA$17.00 - CA$21.00
CA$17.00 - CA$21.00
CA$17.00 - CA$21.00
CA$17.00
CA$40.00 - CA$40.00
CA$40.00
CA$40.00 - CA$40.00
CA$40.00

ZWO IR 850nm Pass Filter – 1.25"

ZWO-850IR1-25
2 in stock

Passes Infrared Light > 850nm Dramatically Steadies Planetary Views in Poor Seeing Enables Daylight Planetary and Lunar Imaging Standard 1.25" ...

View full details
CA$40.00 - CA$40.00
CA$40.00
CA$40.00 - CA$40.00
CA$40.00
CA$26.00 - CA$26.00
CA$26.00
CA$26.00 - CA$26.00
CA$26.00

ZWO IR-Cut Protective Window

Options available
1 variants in stock

21 mm diameter protective window for select ZWO cameras Integrated UV/IR-Cut filter maintains natural color balance 1/4 λ surface flatness preserv...

View full details
CA$26.00 - CA$26.00
CA$26.00
CA$26.00 - CA$26.00
CA$26.00
CA$207.00 - CA$419.00
CA$207.00 - CA$419.00
CA$207.00 - CA$419.00
CA$207.00

ZWO LRGB Optimized Filters

Options available
3 variants in stock

1.25" (31.75mm) Threaded Filter Set Greater than 92% Transmission at Passband Balanced 1:1:1 RGB Exposure Weighting 1/4 Wavefront Polished Optical...

View full details
CA$207.00 - CA$419.00
CA$207.00 - CA$419.00
CA$207.00 - CA$419.00
CA$207.00
CA$517.00 - CA$979.00
CA$517.00 - CA$979.00
CA$517.00 - CA$979.00
CA$517.00

ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII

Options available
1 variants in stock

Includes 1.25" H-alpha, OIII, and SII filters 7nm bandpass for high-contrast imaging Ideal for creating "Hubble Palette" images Fine-optically pol...

View full details
CA$517.00 - CA$979.00
CA$517.00 - CA$979.00
CA$517.00 - CA$979.00
CA$517.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00

ZWO Narrowband H-alpha Filter - 7nm

Options available

Isolates Hydrogen-Alpha light at a 7nm bandpass Standard 1.25" threaded metal cell Blocks light pollution and moonlight for extreme contrast Multi...

View full details
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00 - CA$349.00
CA$181.00

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.