H-alpha Filter
H-alpha Filter

The Askar H-alpha (Ha) 7nm filter is a helpful tool for imaging of H-alpha emitting nebulae or some supernova remnants. The Askar H-alpha filter has an extreme 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 glow. So the Askar H-alpha filter is suitable for astro-imaging in heavily light-pollution hit locations and 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, the 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 most amount of details 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 90% at the peak, 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 of this H-alpha filter in artificially-brighten 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 7mn bandwidth, properly designed for astrophotography both in light polluted or dark locations.

· Useful for imaging H-alpha emitting nebulae, planetary nebulae and supernova remnants.

· High transmission of 90% and excellent 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.

Not recommended

· Visual observation
· Imaging or observation for the Sun