How to Choose Best Astrophotography Filters: Guide for Beginners

Astrophotography isn't just about capturing stars but about maximizing clarity, contrast, and detail in every shot. Without the right filter, even a perfect setup can produce dull, noisy images. With the right one, you reveal stunning detail - right from your backyard.

What Are Astronomical or Astrophotography Filters?

Astrophotography filters selectively isolate the specific wavelengths you want to capture, cutting through background noise from stars, city lights, or the night sky itself. Unlike regular photography, deep-sky imaging deals with extremely faint targets and complex background light. Filters become essential tools, as they block unwanted wavelengths (like light pollution), enhance contrast and clarity of your target, and isolate critical emission lines such as Hα (Hydrogen-alpha) and OIII (Oxygen-III). Monochrome cameras don’t capture color on their own, so filters are mandatory for capturing separate channels (LRGB or SHO) that are later combined into color images. While color cameras with Bayer arrays can capture full-color images in one shot, in light-polluted areas, monochrome setups with filters still deliver superior results. Think of them as precision tools: they let you cut through skyglow and capture what your eyes and your camera can't see on their own.

A high-quality astronomy filter can:

• Suppress star halos
• Boost contrast and detail
• Enhance color saturation
• Improve signal-to-noise ratio

So how should beginners choose the right filters? And what defines a quality astrophotography filter?

 

01  Star Halos

Ever captured the Orion Nebula or Cygnus and noticed a bright star exploding into a huge halo that ruins the shot? That's usually due to poor control of internal reflections around bright stars - something caused by poor control of internal reflections, typically from lower-quality filter coatings.

Lower-quality astrophotography filters suffer from ghosting and halos under strong light sources. In contrast, astrophotography filters from ToupTek Astro feature high-transmission anti-reflective coatings and edge-blackening to significantly reduce internal reflections and stray light interference.

Available sizes:

• 36mm unmounted LRGB+SHO 
• 2-inch with threaded mount LRGB+SHO 
• 1.25” inch LRGB+SHO 

 

02 Coating Technology

In astrophotography, halos are among the most disruptive optical issues. Coatings are your first defense against internal reflections and halos caused by bright stars.

Many assume that multilayer coatings are just a marketing gimmick. They're not. Coating quality fundamentally defines a filter's optical performance. ToupTek Astro astrophotography filters use IAD (Ion-Assisted Deposition) multilayer coating technology. Compared to traditional vacuum deposition, IAD yields denser, more uniform coatings, improving mechanical durability, corrosion resistance, and environmental stability.

Instead of cutting large coated sheets (which can lead to uneven coatings and edge damage), ToupTek Astro coats each filter individually, ensuring every piece has full-surface coating integrity, greatly extending its usable life. You invest once and get years of consistent performance, even in dew, dust, or cold-weather imaging.

Unlike many filters that use dyed glass and basic surface coatings, which can fade or degrade over time, ToupTek Astro filters use precision multilayer coatings on optical-grade quartz glass for long-term performance. This design:

• Increases transmission
• Minimizes internal reflections
• Improves contrast
• Reduces halos
• Enhances image quality

 

03 Vignetting

Noticed dark, shadowy edges in your image after switching to a larger sensor? That's vignetting - often caused by using a filter that’s too small for your sensor's image circle.

For example, this single-frame OIII shot using another brand shows clear vignetting at the corners.

Filters sit in the optical path - often in a wheel or drawer. If the clear aperture is smaller than the sensor's image circle, edge light gets blocked. To avoid this, your filter's clear diameter should be at least 1.5× the image circle. Get this wrong, and you're stuck cropping out your best data. Get it right, and your images stay crisp edge to edge.

ToupTek Astro filters come in:

• 1.25" for sensors up to 1/1.2" (e.g., ATR585M/C, ATR533M/C)
• 36mm for APS-C sensors
• 2" for full-frame astrophotography cameras like the SkyEye series, paired with wide-field scopes

Here's a quick size guide for filter pairing by sensor format:

Sensor Size	Camera	Image Circle Diameter	Recommended Filter Size	Compatibility
Full-frame	SkyEye Series	44mm	2" and above	Large Field of View (FoV) Telescope Deep-sky astrophotography
1"-1.8"	ATR2600M/C ATR533M/C ATR294M/C	28mm	36mm and above	Medium Field of View (FoV) Telescope Deep-sky astrophotography
1" 1/1.2"	ATR183M/C ATR585M/C	16mm	1.25" and above	Small Field of View (FoV) Telescope Planetary astrophotography

 

04 Bandpass Accuracy

Astrophotography filters let in only the wavelengths you need.

• Broadband filters: Ideal for capturing natural star colors and galaxy details
• Narrowband filters: Essential for deep-sky emission nebulae; they reject all but specific emission lines, cutting through light pollution

Critical narrowband lines:

• Hα (656.3nm, red)
• [SII] (671.6nm, deep red)
• [OIII] (500.7nm, blue-green)

ToupTek Astro narrowband filters come in:

• 36mm: 3.5nm Hα, 4nm SII/OIII (ultra-tight bandpass, perfect for light-polluted skies)
• 1.25"/2": 6.5nm bandpass

The 3.5nm Hα filter also captures nearby Nitrogen II (NII) emissions - useful for revealing subtle structures in regions like Orion or the Horsehead Nebula. This lets you reveal the delicate gas tendrils most filters miss, especially in nebula-rich targets like Orion or IC434.

Spectral Curves

1. 1.25" and 2" SHO narrowband filters
2. 36mm SHO narrowband filters
3. 1.25" and 2" LRGB filters
4. 36mm LRGB filters

05 Transmission Efficiency

Transmission refers to the percentage of target light that passes through the filter. The higher the better - more photons, brighter images, more detail, higher SNR.

ToupTek Astro astrophotography LRGB filters boast 95 %+ peak transmission, reducing exposure time and stack count, helping you get more done in less time.

 

06 Choosing the Right Bandwidth (FWHM)

The bandwidth (full width at half maximum) defines how narrow or wide a filter's passband is.

• Narrower filters (e.g., ≤5nm) block more light pollution - deal for urban imaging but demand longer exposures and better optics.
• Wider filters (5–7nm) balance contrast and ease of use - great for moderate light pollution and wider compatibility.

Recommended Setups:

• Budget-friendly: ATR585M (1/1.2") + small Newtonian + 1.25" SHO filters
• Premium: 36mm 4nm filters for top-tier results

 

07 Performance

Want to see what these filters can do? Here are real-world images from fellow astrophotographers using ToupTek Astro filters - along with their gear and exposure details.

1.25" filters

M81 & M82 © yahushua

• Telescope:  Sharpstar 130HNT28-AL
• Camera: Touptek Astro ATR585M
• Guide Camera: G3M2210M
• Mount: iOptron CEM26
• Filters: Touptek Astro 1.25" LRGB + Hα
• Exposure: 14 hrs

 

M16 Eagle Nebula © yahushua

• Telescope: Sharpstar 130HNT28-AL
• Camera: Touptek Astro ATR585M
• Guide Camera: G3M2210M
• Mount: iOptron CEM26
• Filters: Touptek Astro 1.25" SHO
• Exposure: 7 hrs
  

 

36mm filter

IC5070 Pelican Nebula © voice

• Telescope: Sky-Watcher BKP200/800
• Camera: ToupTek Astro ATR2600M
• Filters:  ToupTek Astro 36mm LRGB+SHO
• Exposure: 15 hrs

 

NGC1999 Ghost Nebula © voice

• Telescope: Sky-Watcher BKP200/800 f/3.4
• Camera: ATR2600M
• Guide Camera: GPM462M
• Filters: 36mm LRGB+SHO
• Exposure: 20 hrs

 

2" filters

NGC6357 Lobster Nebula © voice

• Telescope: Sky-Watcher BKP200/800
• Camera: ASI2600M
• Filters:  ToupTek Astro 2" SHO
• Exposure: 18 hrs
  

 

Pelican Nebula © Dscad

• Telescope: Airy Disk 106APO
• Camera: SkyEye62AM
• Filters:  ToupTek Astro 2" LRGB
• Exposure: 16 hrs

 

08 Pro Tip: How to Orient Your ToupTek Astro Filters

All ToupTek Astro filters are edge-blackened to suppress stray light and distinguish orientation.

• 36mm unmounted: The side with the black ring facing toward the center should face the telescope.
• 1.25"/2" threaded filters: Simply screw into the wheel or drawer—no need to check coating direction.