Description Visual Narrowband O-III Filter - 1.25" (BPO3125) and 2" (BPO32) The non plus ultra for visual deep-sky observers, especially under extremely light-polluted skies. See planetary nebulae and supernova remnants come alive with the enhanced contrast from these filters. Among the narrowest transmission band O-III filters on the market, ideally suited for both visual use and for many imaging applications thanks to its unsurpassed contrast. No image degradation is perceptible even at the highest magnifications. Features the same ultra-hard, extremely durable vacuum-deposited dielectric coatings employed on the UHC-S filter. The Baader Visual O-III Filter effectively blocks the entire visual spectrum with the exception of the two closely paired emission lines from doubly ionized oxygen, eliminating the annoying colored halos surrounding stars that often appear through O-III filters manufactured by means of less sophisticated coating technology. We also offer two additional versions of this filter with extended infra-red blockage for many of today's IR sensitive CCD chips - in a 2" mounted and in a 50.8 mm unmounted configuration for the STL series of cameras. Transmission Curve - PDF documentExtended Transmission Curve
