Askar H-Alpha 7nm Narrowband Imaging Filter - 36mm Unmounted
Askar H-Alpha 7nm Narrowband Imaging Filter - 36mm Unmounted (glass only)
The Askar H-alpha (Ha) 7nm filter is a helpful tool for imaging H-alpha emitting nebulae or some supernova remnants. The Askar H-alpha filter has an extremely high transmission at a center wavelength of 656.3nm. The 7nm narrow bandwidth enables this nebula-imaging filter to block all the light pollution and other unwanted artificial lights or night sky glow. So the Askar H-alpha filter is suitable for astro-imaging in heavily light-polluted locations, but also delivers enhanced contrast at darker places.
The Askar H-alpha filter is designed for further improving the contrast and details of various types of nebulae and supernova remnants, a large emission nebulae in some spiral galaxies, for example. It works well on those nebulae emitting ionized hydrogen or the H II regions in nearby galaxies. Featuring 7nm narrow bandwidth and a greatly high transmission at a center wavelength of 656.3nm, the Askar H-alpha filter can bring out the highest amount of detail of the nebulae and supernova remnants. Also, the out-of-band blocking ability is rated with OD4 (0.01%) with the blocking range of 200-1050nm. It delivers an excellent signal-to-noise ratio and a sharp cut-off rate to attenuate the disturbance from other wavelengths.
The narrow bandwidth and an effective cut-off rate are important indices when choosing a narrowband filter. The Askar H-alpha filter has a narrow bandwidth of 7nm and an extreme transmission of minimum 90% at the peak usually closer to 95%), in the meanwhile, sufficiently blocking other off-band wavelength. That’s why we sometimes call those 7nm-bandwidth, or even a smaller bandwidth of 3nm, a line filter. So the Askar H-alpha filter can efficiently reject all the light pollution. You can expect a terrific performance from this H-alpha filter in artificially-illuminated background sky.
The production process is strictly controlled and every single Askar H-alpha narrowband filter is individually examined and tested to ensure that they can highly satisfy the observing interests and needs of our customers.
- Narrow 7nm bandwidth, properly designed for astrophotography both in light polluted or dark locations.
- Useful for imaging emission nebulae, planetary nebulae and supernova remnants.
- High transmission of 90-95% and sharp cut-off can greatly enhance the contrast and bring out the most detailed information for those deep-sky objects.
- Designed to sharply cut off the inference of artificial light from sodium vapor or mercury vapor street lights and other unwanted disturbance like sky glow.
- The Askar H-alpha narrowband filter is not suitable for visual observation and not designed for imaging or observing the sun or other non-Ha-emitting objects.
ATTENTION! DO NOT USE THIS FILTER FOR OBSERVING THE SUN! PERMANENT EYE DAMAGE MIGHT BE THE RESULT IF YOU DO.
Images are for demonstration purcposes only. Might show a similar product or the same product, but different size.
Askar H-alpha Narrowband (7nm) Filter Specifications
round and unmounted
Angle of incidence
FWHM (full width at half maximum)
CWL (central wavelength)
＞90% at 656.3nm
OD4(0.01%) @ 200-1050nm