ZWO 31mm Ha 7nm Narrowband Unmounted Filter
Best high contrast imaging for dedicated astrophotography enthusiasts.
Designed to enhance contrast between the night sky and nebulae, this tool is essential for astrophotography. It utilizes a 7nm bandpass and an 80% light transmission rate to capture detailed images in light-polluted environments. By filtering out wavelengths from artificial light sources, it allows for clearer observation of celestial objects.
$149.00
More Narrowband Filter Options
Owner Satisfaction
4.7
/ 5
Category Rank
607
/ 2593
#607 in Telescope Accessories
Price vs Category Average
-78%
Below average
Bandpass
7
/ nm
Who it's for
- Urban astrophotographers seeking to image nebulae despite light pollution
- Imagers prioritizing sharp, detailed views of emission nebulae
- Experienced users with compatible filter wheels or custom mounting solutions
Who should skip it
- Newcomers without existing filter holders or specific mounting accessories
- Astrophotographers desiring a single filter for diverse celestial targets
- Users preferring robust, easy-to-handle filters for frequent changes
Performance breakdown
Light Pollution Suppression
Effectively isolates hydrogen-alpha signals even in heavily light-polluted urban skies.
Contrast Enhancement
Significantly boosts nebula definition against the backdrop of the night sky.
Optical Transmission
High light throughput ensures efficient signal capture during long-exposure imaging sessions.
Bandpass Precision
The 7nm window strikes an ideal balance between selectivity and signal strength.
Installation Versatility
Unmounted format requires specific filter wheel compatibility for secure integration.
Build Durability
Robust glass construction stands up well to frequent handling and environmental exposure.
Key Specs
Bandpass
7nm
Transmission
80%
Filter Shape
Round
Filter Diameter
31mm
Thickness
2mm
Format
Unmounted
Case Included
No
Know before you buy
A 7nm bandpass is a narrow window that allows only the specific light emitted by Hydrogen-alpha ionized gas to pass through. This effectively blocks out most other wavelengths, including light pollution and moonlight, which significantly increases the contrast of nebulae in your images.
No, this is an unmounted filter. It is designed to be installed directly into a compatible filter wheel or drawer that accepts 31mm round filters.
Yes, this filter is specifically designed for light-polluted environments. By isolating the Hydrogen-alpha emission line, it suppresses the artificial light from streetlamps and city glow, allowing you to capture deep-sky details that would otherwise be washed out.
This filter is primarily engineered for long-exposure astrophotography with monochrome cameras. While it can technically be used visually, the 7nm bandpass is extremely narrow, making the view very dim and unsuitable for standard eyepiece observation.
While it can be used with one-shot color cameras, it is most effective when paired with a monochrome camera. If you use it with a color camera, you will only be capturing data on the red pixels, which limits the efficiency of your sensor.
Still have a question?
Ask Hayley anything about this product before you decide.