The 2" narrowband UHC filter, like the O-III filter, isolates the two doubly ionized oxygen lines (496 and 501nm) in addition to the hydrogen-beta line (486nm) emitted by planetary and most emission nebulae. This filter permits superb views of objects like the Orion, Ring, Dumbell, Swan and other extended nebulae. It performs well in smaller aperture instruments owing to its greater light transmission than the O-III, yet still suppresses light pollution well. The UHC filter is the best all round nebula filter giving a new lease of life to deep sky observing with any instrument. The filter threaded to fit either standard filter threads in 2" astronomical eyepieces and accessories and is supplied in a protective storage case.
