Skip to content

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$251.99 - CA$251.99
CA$251.99
CA$251.99 - CA$251.99
CA$251.99

Explore Scientific Nebula Filter H-Beta - 2.0"

ES-310230

2.0-inch Barrel Size Isolates Hydrogen-Beta (H-Beta) Emission Line Dramatically Increases Contrast on Specific Nebulae Blocks Artificial Light Pol...

View full details
CA$251.99 - CA$251.99
CA$251.99
CA$251.99 - CA$251.99
CA$251.99
Explore Scientific Nebula Filter S-II 1.25-inch 12nm
CA$224.00 - CA$224.00
CA$224.00
CA$224.00 - CA$224.00
CA$224.00

Explore Scientific Nebula Filter S-II 1.25-inch 12nm

ES-310115

Isolates the ionized sulfur (S-II) emission line at 672nm Features a 12nm bandpass to increase contrast Standard 1.25-inch filter format Ideal for...

View full details
CA$224.00 - CA$224.00
CA$224.00
CA$224.00 - CA$224.00
CA$224.00
Explore Scientific Nebula Filter S-II 1.25-inch 6.5nm
CA$280.00 - CA$280.00
CA$280.00
CA$280.00 - CA$280.00
CA$280.00

Explore Scientific Nebula Filter S-II 1.25-inch 6.5nm

ES-310125

Isolates the ionized sulfur (S-II) emission line at 672nm Ultra-narrow 6.5nm bandpass for maximum contrast Standard 1.25-inch barrel size fits mos...

View full details
CA$280.00 - CA$280.00
CA$280.00
CA$280.00 - CA$280.00
CA$280.00
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...

View full details
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...

View full details
CA$420.00 - CA$420.00
CA$420.00
CA$420.00 - CA$420.00
CA$420.00
CA$69.99 - CA$69.99
CA$69.99
CA$69.99 - CA$69.99
CA$69.99

Explore Scientific Neutral Density Filter ND 0.9 - 1.25"

ES-310245
1 in stock

ND 0.9 Optical Density 1.25" Barrel Diameter Reduces Glare for Lunar Observing Aids in Splitting Unequal Double Stars Uniform Light Transmission A...

View full details
CA$69.99 - CA$69.99
CA$69.99
CA$69.99 - CA$69.99
CA$69.99
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
iOptron Green Moon Filter
CA$20.00 - CA$20.00
CA$20.00
CA$20.00 - CA$20.00
CA$20.00

iOptron Green Moon Filter

IOP-TFE100

Enhances contrast on lunar and planetary features Reduces glare for more comfortable viewing Improves detail in Martian polar caps and dust storms...

View full details
CA$20.00 - CA$20.00
CA$20.00
CA$20.00 - CA$20.00
CA$20.00
iOptron LRGB Imaging Filter Kit - 1.25"
CA$307.00 - CA$307.00
CA$307.00
CA$307.00 - CA$307.00
CA$307.00

iOptron LRGB Imaging Filter Kit - 1.25"

IOP-3383-LRGB

Complete LRGB Filter Set Includes Luminance, Red, Green, and Blue Filters Standard 1.25" Filter Size Threaded for Standard Filter Wheels and Acces...

View full details
CA$307.00 - CA$307.00
CA$307.00
CA$307.00 - CA$307.00
CA$307.00
CA$82.00 - CA$85.00
CA$82.00 - CA$85.00
CA$82.00 - CA$85.00
CA$82.00

Lumicon Neutral Density Filter

Options available
1 variants in stock

ND13Lumicon Neutral Density 13 Filter will tone down the glare from the full Moon and allow more planetary detail than ever! Lumicon ND13 transmits...

View full details
CA$82.00 - CA$85.00
CA$82.00 - CA$85.00
CA$82.00 - CA$85.00
CA$82.00
CA$36.00 - CA$45.00
CA$36.00 - CA$45.00
CA$36.00 - CA$45.00
CA$36.00

Lunt Polarizing Filter

Options available

Variable brightness control for solar viewing Available in 1.25" and 2" barrel sizes Threads directly onto standard eyepieces Engineered for use w...

View full details
CA$36.00 - CA$45.00
CA$36.00 - CA$45.00
CA$36.00 - CA$45.00
CA$36.00
Optolong Clear Sky Light Pollution Filter
CA$139.00 - CA$287.00
CA$139.00 - CA$287.00
CA$139.00 - CA$287.00
CA$139.00

Optolong Clear Sky Light Pollution Filter

Options available

Suppresses common sources of urban light pollution Enhances contrast for deep-sky objects Improves natural color balance in astrophotography Durab...

View full details
CA$139.00 - CA$287.00
CA$139.00 - CA$287.00
CA$139.00 - CA$287.00
CA$139.00
Optolong CLS Light Pollution Filter
CA$77.00 - CA$119.00
CA$77.00 - CA$119.00
CA$77.00 - CA$119.00
CA$77.00

Optolong CLS Light Pollution Filter

Options available

Suppresses common light pollution sources Average transmission greater than 90% on key nebula emission lines Blocks light pollution lines with >...

View full details
CA$77.00 - CA$119.00
CA$77.00 - CA$119.00
CA$77.00 - CA$119.00
CA$77.00
Optolong CLS-CCD Light Pollution Filter
CA$133.00 - CA$223.00
CA$133.00 - CA$223.00
CA$133.00 - CA$223.00
CA$133.00

Optolong CLS-CCD Light Pollution Filter

Options available

Blocks >99% of primary light pollution emission lines Achieves >90% average transmission on key nebula wavelengths Integrated 300-1100nm UV/...

View full details
CA$133.00 - CA$223.00
CA$133.00 - CA$223.00
CA$133.00 - CA$223.00
CA$133.00
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...

View full details
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...

View full details
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...

View full details
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 ...

View full details
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$110.00 - CA$161.00
CA$110.00 - CA$161.00
CA$110.00 - CA$161.00
CA$110.00

Optolong IR Pass 685nm Planetary Filter

Options available
3 variants in stock

Passes infrared light above 685nm Achieves greater than 90% peak transmission Blocks wavelengths from 350-1050nm outside the passband 1.85mm thick...

View full details
CA$110.00 - CA$161.00
CA$110.00 - CA$161.00
CA$110.00 - CA$161.00
CA$110.00
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...

View full details
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...

View full details
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
8 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...

View full details
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) ...

View full details
CA$362.00 - CA$362.00
CA$362.00
CA$362.00 - CA$362.00
CA$362.00
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00

Optolong L-Pro + UHC Clip Filter Kit

Options available

Two Optolong Clip-in Light Pollution Filters in One Kit L-Pro: Multi-Bandpass Suppression Across 380-750nm UHC: >99% Blocking of Mercury and So...

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

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.