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The Askar O III 7nm filter is suitable for imaging of O III emitting nebulae or some supernova remnants. The Askar O III filter has an extreme high transmission at a center wavelength of 500.7nm. The 7nm narrow bandwidth enables this astroimaging filter to block all the light pollution and other unwanted artificial lights or night glow. So the Askar O III filter is an ideal instrument for astro-imaging in heavily light-pollution hit locations and delivers enhanced contrast at darker places.
The Askar O III filter is designed for improving the contrast and details of some nebulae and supernova remnants. It works well on those nebulae emitting O III. Featuring 7nm narrow bandwidth and a greatly high transmission at a center wavelength of 500.7nm, the Askar O III filter can bring out the most amount of details of the emission nebulae, planetary 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 O III filter has a narrow bandwidth of 7nm and an extreme transmission of 90% at the peak, in the meanwhile, sufficiently suppressing 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 O III filter can efficiently reject all the light pollution. You can expect a terrific performance of this O III filter in artificially-brighten background sky.
The production process is strictly controlled and every single Askar O III 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 O III 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 O III narrowband filter is not suitable for visual observation and not designed for imaging or observing the Sun or other non-O III-emitting objects.