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
SBIG Filter Inserts 36mm to 1.25"
Individual inserts that allow the use of 1.25″ filters in threaded cells to be used instead of 36mm unmounted filters in the FW8-8300 and FW8S-Alum...
View full detailsSBIG FW8-8300 for STF
Compatible with: Specifications Power 12 VDC Computer Interface I2C OS Compatibility Windows 32 and 64 bit OS, Mac Weight 1.35 lbs Filter...
View full detailsSBIG Standard Cover for FW8-Aluma
Standard front cover for Aluma filter wheel – replaces the self-guiding front cover when minimum back focus distance is needed.
SBIG Standard Cover FW8-STXL
Standard front cover for STXL filter wheel – replaces the self-guiding front cover for use with camera lens adapters.
SBIG STX 5 x 65mm Square Filter Wheel
Special order only. Specifications Computer Interface I2C OS Compatibility Windows 32 and 64 bit OS, Mac Weight 4.35 lbs Filter Size 65mm S...
View full detailsSBIG STX 7 x 50mm Square Filter Wheel
The SBIG FW7-STX is a 7-Position, 50mm square filter wheel for STX and Aluma AC series cameras.The SBIG FW7-STX is a 7-Position, 50mm square filter...
View full detailsSBIG STXL 8 x 36mm Filter Wheel
The SBIG FW8S-STXL provides 8 filter slots for all SBIG STXL camera models. Specifications Filter Size 36mm / 1.25" Weight 2 lbs OS Compatibi...
View full detailsSBIG Threaded 1.25" Filter Cell with Retainer for 1.1" Unmounted Filters
This is a 1.25″ screw-in filter cell for unmounted 1.1″ standard glass filters. The cell includes a retaining ring for holding the filter in place.
Starizona Modular Filter Slider Plates
Starizona Modular Filter Slider Plates
Starizona RASA 8 Filter Holder - M42 Threads
The RASA 8 Filter Holder allows the use of 2" filters on Celestron's RASA 8" telescope with a camera using M42 threads and having a 17.5mm backfoc...
View full detailsSVBONY CLS Light Pollution Broadband Filter
Broadband Light Pollution Suppression Effectively Blocks Sodium and Mercury Vapor Streetlights High Transmission on Key Nebula Emission Lines Opti...
View full detailsSVBONY Linear Polarizer Filter
Reduces light transmission to a comfortable 13% for lunar viewing Standard 1.25-inch barrel size fits most eyepieces and accessories Threads into ...
View full detailsSVBONY Moon Filter
Reduces glare for comfortable lunar and planetary observing Fits any standard 1.25" eyepiece or accessory Standard M28.5x0.6 filter threads Enhanc...
View full detailsSVBONY SV115 18nm OIII Narrowband Filter
2-inch diameter filter for standard eyepieces and accessories 18nm bandpass isolates key Oxygen-III emission lines 90% peak transmittance at 495.9...
View full detailsSVBONY SV128 Variable Polarizing Filter
Available in 1.25" and 2" barrel sizes Continuously variable light transmission Reduces glare for enhanced lunar and planetary contrast Constructe...
View full detailsSVBONY SV132 25nm H-Beta Narrowband Filter
Targets the 486nm Hydrogen-Beta emission line 25nm bandpass for enhanced contrast 80% peak transmittance at the H-Beta wavelength Blocks Mercury (...
View full detailsSVBONY SV133 5-Position Filter Wheel - 1.25"
Accommodates five standard 1.25" threaded filters Manual wheel with precise click-stop positioning T2-threaded connections for direct camera attac...
View full detailsSVBONY SV133 5-Position Filter Wheel - 2"
Accommodates five 2-inch filters 2-inch barrel for telescope connection 2-inch eyepiece and camera compatibility Enables rapid filter changes duri...
View full detailsSVBONY SV139 ND0.6 Neutral Density Moon Filter - 1.25"
Reduces lunar glare with a fixed ND0.6 optical density Transmits a neutral 25% of incoming light Standard 1.25-inch barrel fits most eyepieces Mul...
View full detailsSVBONY SV139 ND0.9 Neutral Density Moon Filter - 1.25"
Reduces lunar brightness by ~87.5% (ND0.9) Fits any standard 1.25-inch eyepiece or accessory Neutral density filter preserves true color balance F...
View full detailsSVBONY SV139 ND1.2 Neutral Density Moon Filter - 1.25"
Reduces Lunar Glare with ND1.2 Density Transmits 6.25% of Incoming Light Standard 1.25-inch Barrel Threads Fully Multi-Coated Optical Glass Neutra...
View full detailsSVBONY SV139 ND3.0 Neutral Density Moon Filter - 1.25"
ND3.0 Neutral Density Filter Standard 1.25-inch Barrel Size Transmits 0.1% of Incoming Light (10-Stop / 1000× Reduction) Ideal for Herschel Solar ...
View full detailsSVBONY SV155 7-Piece Telescope Filter Set - 1.25"
7-Piece Filter Set Includes Moon, CPL, and 5 Color Filters Standard 1.25-inch Barrel Size M28.5*0.6 Filter Threads 2mm Thick Optical Glass Desc...
View full detailsSVBONY SV164 Dark Filter for CCD and CMOS Cameras
2-inch Filter Size Standard M48x0.75 Threads Enables Automated Dark Frame Capture 1mm Filter Thickness Durable Anodized Aluminum Cell Descripti...
View full detailsFilter 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.