Narrowband filter for the OIII lines at 495.9 and 500.7 nm
This filter is suitable for observation and photographing OIII regions from areas affected by light pollution or areas with dark skies.
The OIII filter increases the contrast between certain types of astronomical objects (mainly supernova remnants and planetary nebulae) and the sky background. Due to its narrow half-width and high transmission in the OIII line range, it achieves a greater contrast increase than filters with a larger bandwidth. The range of application extends from an aperture ratio of 1:3 to 1:15 for telescopes with an aperture of 6" (150 mm) or more for observation at medium magnification and lenses and telescopes of all diameters for astrophotography.
Mode of action
The filter completely blocks the emission lines of low- and high-pressure lamps (mercury (Hg) and sodium (Na)) and the lines of the airglow. The two OIII lines can pass through the filter with very high transmission.
