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Also known as the Horsehead Nebula filter, the Lumicon Cassegrain Hydrogen-Beta Filter isolates only the hydrogen-beta line of the spectrum (486nm) in a narrow pass-band just 9 nm wide, providing maximum contrast. The Cassegrain filter-cell 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 12" or larger telescopes
Now you can view extremely faint nebulous objects such as the Horsehead, Cocoon and California Nebulae
In many cases, the Lumicon Hydrogen-Beta Filter is the ONLY way to view these objects
To ensure that your Lumicon filter remains the world's best, the strictest quality control standards are employed throughout the production process
Each Lumicon Hydrogen-Beta Filter is individually inspected and proudly inscribed with the percentage of light transmittance of the H-Beta emission line