2" Narrowband O-III Filter (BPO32)

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We offer 1.25" (BPO3125) and 2" (BPO32) versions of this filter.

  • Ultra hard and bright O-III visual contrast for 6" and larger telescopes
  • No visual color fringing, just pure O-III
  • Non-ageing sealed coating edges

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.

Transmission Curve

Spectral Position by Color