The Askar O III 5nm 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 500.5nm. The 5nm 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. Besides, the special design of Askar O III filter makes it enable to reduce the bloating problem, with which an astrophotographer is frequently confront when shooting with an ordinary O III filter.