The legendary Lumicon Cassegrain OIII narrow band-pass filter threads onto your telescope’s SCT rear-cell, and presents male SCT threads for accessory attachment. The Cassegrain filter cell allows you to change eyepieces without threading/unthreading the filter, and is also easier to change-out than the standard 2″ filter cell with gloves on, for cold-weather observing.
Visually, the Lumicon Cassegrain OIII filter isolates just the two doubly ionized oxygen lines (496 and 501nm lines) emitted by diffuse, planetary and extremely faint nebulae. Thus, these faint objects become much more visible against the blackened background of space. The Lumicon Oxygen III Filter produces near-photographic views of the Veil, Ring, Dumbbell and Orion nebula, among many other objects. Performs well under both light-polluted and dark skies.
To ensure that your Lumicon filter remains the World’s Best, the strictest quality control standards are employed throughout the production process. Each Lumicon Oxygen III Filter is individually inspected and proudly inscribed with the percentage of light transmittance of the OIII emission lines.