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Astrodon 3 nm H-Alpha Narrowband Filter - 36 mm Round Unmounted - HA3-36R

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About Astrodon Narrowband Filters

Astrodon filters are high performing, durable filters that provide significant aid for astrophotography and research pursuits. Each filter is constructed using a highly innovative process with a single high quality 3 mm thick fused silica substrate and full hard oxide sputtered coatings. With these Astrodon Narrowband filters, imagers can count on consistently high performance, as well as a more narrow spectrum compared to most other filters for superb contrast and the ability to view the faintest nebula detail. Astrodon guarantees >90%T performance at the emission line.

Astrodon 3 nm Narrowband Filter Highlights

  • Guaranteed 90%+ maximum transmission for the highest achieveable performance
  • 3 nm bandwidth
  • 36 mm unthreaded
  • >OD 4 (0.01% transmission) out-of-band blocking
  • Clear 1/4 wave substrates feature hard-oxide coatings to the edge, removing light leakage from uncoated rims
  • Edge blackened to reduce reflections
  • Parfocal with all other filters made by Astrodon.

Astrodon 3 nm H-Alpha Narrowband Filters

Highly favored among narrowband filters, hydrogen-alpha filters for 656 nm are deep red in color. As it is the most common element in the universe, hydrogen is present in emission nebula such as the North American and the Pelican, planetary nebula such as the Dumbbell and Ring, Wolf-Rayet objects like Cresecent and Thor's Helmet, as well as supernova remnants like the Veil nebula. While many imagers are content to dsiplay a simple black and white h-alpha image of an object, most imagers will want to combine their h-alpha data with their red RGB data in order to augment structural detail while preserving a "natural" appearance. For this reason, h-alpha filters make a perfect initial narrowband extension of your LRGB filters.

Astrodon Narrowband Filters - Additional Information

Astrodon Narrowband filters enhance emission line object contrast through their narrow 5 nm and 3 nm bandwidths, setting a new standard for imaging and research performance and reliability. With a guaranteed transmittance of more than 90% at the emission wavelength providing the highest available signal, combined with such spectrally narrow bandwidth filters, imagers can be confident of attaining maximum contrast. Astrodon's latest narrowband filters, as a matter of fact, typically achieve between 95% and 98% transmittance. Acclaimed for their ability to reduce halos around bright stars, Astrodon Narrowband filters are still able to accomplish this even for long 30 to 45 minute exposures common to narrowband astrophotography. Finally, these edge blackened Astrodon Narrowband filters contain hard-oxide coatings to the perimeter to eliminate any chance of light leaking due to an uncoated border. For a filter that blocks most light save for the narrow bandpass, this becomes crucial to maintaining as low a level of stray light as possible.
The most important aspect of Astrodon Narrowband filters is the improved contrast they provide. As contrast improves, faint detail of emission line objects such as planetary nebulae and remnants of supernovae is further enhanced. With filters that have narrower bandwidths, this effect is even more pronounced. The downside is that keeping a constant signal (% transmission at the emission line) can be an issue with spectrally narrower filters. This is where Astrodon's >90%T guarantee comes in. With this guarantee, you'll know that you can depend on being able to take advantage of the improved contrast offered by filters with narrower bandwidths.
Main image may not depict the exact filter you receive.