ZWO 2-Inch H-alpha Filter - 7nm
Best narrowband filter for astrophotographers capturing detailed nebulae in light-polluted areas.
This specialized narrowband filter is engineered to enhance deep-sky observations by isolating the H-alpha emission line. It effectively minimizes interference from light pollution sources and atmospheric emissions, significantly increasing contrast between celestial objects and the night sky. This allows for the revelation of finer details in nebulae and other emission objects. The filter offers high transmission for brighter images and is crafted with precision optics for sharp, clear results, making it ideal for astrophotography and visual observation.
$249.00
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Owner Satisfaction
4.7
/ 5
Category Rank
82
/ 1292
#82 in Lens Filters
Price vs Category Average
+31%
Above average
Filter Type
H Alpha
/ H Alpha
Who it's for
- Urban astrophotographers battling heavy light pollution
- Deep-sky imagers seeking sharp nebular detail
- Advanced users with standard filter wheel setups
Who should skip it
- Photographers wanting full-color images without extra filters
- Beginners lacking the patience for long exposure times
- Budget-conscious hobbyists building their first imaging kit
Performance breakdown
Light Pollution Suppression
Effectively isolates the H-alpha line to cut through urban skyglow.
Optical Transmission
High throughput ensures bright, clear signals for deep-sky imaging sessions.
Bandpass Precision
The 7nm window provides excellent contrast for capturing faint nebular structures.
Surface Quality
Fine-polished glass maintains sharp detail across the entire sensor frame.
Build Integrity
Robust construction with standard threading makes for a reliable, secure fit.
Imaging Versatility
Optimized for H-alpha, though limited to specific emission-line celestial targets.
Key Specs
Filter Type
H Alpha
Bandpass
7nm
Wavelength
656nm
Light Transmission Rate
80%
Glass Polishing
Fine-optically polished, 1/4 wavefront accuracy
Thread
M48x0.75 male thread
Size
2-inch
Filter Shape
Round
Know before you buy
The 7nm bandpass is narrow enough to effectively block most light pollution and skyglow while allowing the specific 656nm H-alpha wavelength to pass through. This significantly boosts the contrast of emission nebulae, making them stand out against the background sky.
This is a 2-inch round filter with a standard M48x0.75 male thread. It is designed to screw directly into most 2-inch filter wheels, camera adapters, or eyepiece barrels that accept 2-inch threaded filters.
While it is optimized for astrophotography, it can be used for visual observation. However, because the 7nm bandpass is very narrow, you will need a telescope with a large aperture to gather enough light for a clear view of the nebula.
An 80% transmission rate is quite high for a narrowband filter, which helps keep your exposure times manageable. It ensures that you capture enough signal from the target object without needing excessively long exposures.
Yes, the 1/4 wavefront accuracy ensures that the glass does not introduce distortions or aberrations into your optical train. This maintains the sharpness of your stars and fine details in nebulae across the entire frame.
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$249