Telescopes & Astronomy

Bring out the best in your nebulae astroimages with the H-alpha H-beta OIII (Hα-Hβ-OIII) Imaging Filter for the 8” RASA. This specialized filter allows high transmission of light from emission nebulae while blocking light pollution, helping to make your images pop with detail off the black sky background with superior contrast.

Fortunately, many sources of light pollution have relatively discreet emission spectra; they emit primarily at specific wavelengths of light. By strategically blocking these “bad” wavelengths, the filter essentially eliminates the effect of light pollution while letting the “good” wavelengths of light associated with the emission nebula pass through to the camera. You’ll notice much higher contrast in your images immediately, even if imaging from your light polluted backyard! And since the transmission at the key wavelengths is so high, the nebula will not be dimmed—only the background will be blacker.

• Enhance your 8” Rowe-Ackermann Schmidt Astrograph (RASA) by blocking light pollution, improving image contrast, and darkening the sky background.
• This filter selectively blocks wavelengths of light from sources of light pollution, such as streetlights, not broad regions of the spectrum.
• Does not block wavelengths associated with emission nebulae, keeping your nebula images bright and detailed.
• Fits into the 8” RASA’s integrated filter mount, maintaining peak optical performance.
• Optically flat surfaces free of defects, constructed of Schott glass with anti-reflection coatings.

Astrodon Narrowband filters set a new bar of performance and durability for imaging and research.

Astrodon 5nm Narrowband Filters – H-alpha 5nm

H-α (hydrogen-alpha) at 656 nm (nanometers) is deep red in color and the most popular narrowband filter. Hydrogen is ubiquitous in the cosmos and is present in emission nebula (North American, Pelican), planetary nebula (Dumbbell, Ring), Wolf-Rayet objects (Crescent, Thor’s Helmet) and supernova remnants (Veil).

The ZWO 7nm OIII filter is centered around the Oxygen III band of 501nm. Oxygen III or double ionised oxygen occurs at  primarily at 500.7nm and secondarily 495.9nm.  The highest levels of OIII are usually found in diffuse and planetary nebulae. The OIII emission lines were first discovered in the 1860s in spectra of planetary nebulae.  OIII wavelengths relate to the green-turquoise-cyan in colour on the spectrum whilst the narrowband width makes the background space very black.

The ZWO narrowband O-III 7nm filter is designed for nebula observation allowing 7nm bandwidth of light centered on a wavelength of 500nm through,  which corresponds to OIII emission lines, blocking out all other light.  Adding the ZWO O-III Narrowband filter to your imaging collection will help you go beyond the RGB imaging and will help capture your favorite nebulas in a totally new light, no matter how polluted your skies may be!

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• Fits Optical Tube Diameter 11 5/8" (295mm) to 11 7/8" (302mm)
• Safe for viewing the Sun
• Blocks 99.999% of incoming light
• Compatibility: LX90 10", LX200 10", LX600 10"