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The legendary Lumicon Cassegrain Oxygen III Rear Cell narrow band-pass filter threads onto your telescope's SCT rear-cell, and presents male SCT threads for accessory attachment.
Lumicon knows that all sky viewing is not done under the best of weather conditions. 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.
Note: Recommended for telescopes 10" or larger in aperture
Visually, the Lumicon Cassegrain Oxygen III filter isolates just the two doubly ionized oxygen lines (496 and 501nm lines emitted by diffuse, planetary and extremely faint nebulae; 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