Antlia 3nm Narrowband Sulfur II (SII) Pro Imaging Filter - 2":*BRAND NEW-UNOPENED*

The Antlia Sulfur II (SII) 3.0nm filter is suitable for imaging of SII emissions from nebulas, planetary nebulas and supernova remnants. The 3.0nm bandwidth delivers a high transmission at a center wavelength of 671.6nm. The extreme narrowness in bandwidth enables astro-imaging from heavily light polluted locations and delivers improved contrast at darker sites. The filter effectively suppresses interference from other wavelengths, especially artificial mercury and sodium lamps. Antlia narrowband filters are designed to bring out the faintest features in nebulosity by reducing the unwanted background frequencies – the narrower the filter, the better. Antlia's SII filter is designed to deliver 90% transmission at the 671.6nm line. The out-of-band blocking specification is rated OD3 (0.1%) which delivers an excellent signal-to-noise ratio and effective cut-off rate to minimize interference from other wavelengths. A sharp cut-off rate is a very important performance index since it is designed to sharply attenuate off-band wavelengths. The result is that the Antlia SII filter delivers excellent contrast with extremely dark backgrounds whilst delivering a high transmission of the SII signal. The sharp cut-off also minimizes the effect of halos around bright stars. In the production process, Antlia uses very strict quality control standards. Each filter is individually tested and scanned to ensure that the product meets their high-performance parameters. Their exacting attention to tolerances requires each substrate to have a uniform thickness that achieves no more +/-0.05mm deviation from specification.