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Open Box Astrodon 1.25" Ha 5nm Narrowband Filter

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  • Regular price $380.00
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Open Box Astrodon 1.25" Ha 5nm Narrowband Filter

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 5 nm Narrowband Filter Highlights



    • Guaranteed 90%+ maximum transmission for the highest achievable performance


    • 5 nm bandwidth


    • 1.25" Round Mounted


    • >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

Highly favored among narrowband filters, hydrogen-alpha filters for 656.3 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.


After the H-Alpha filter has been incorporated into your collection, the next filter you should consider adding is the OIII filter. The OIII (or Oxygen 3) filter transmits light near 500 nm and has a bluish-green or teal color. Taken with only H-Alpha and OIII filters, faint structural detail of planetary nebulae and supernova remnants is emphasized with natural color as if the image were taken using RGB filters.


Following the additions of the H-Alpha and OIII filters, the next filter you'll need to add to your collection is the SII or Sulfur II filter, especially if you want to view Hubble Space Telescope (HST) images like the popular "Pillars of Creation" (Eagle Nebula, Messier 16). Like the H-Alpha filter, the SII filter also has a deep red color close to 672 nm. For many emission nebulae, H-Alpha, OIII, and SII filters all give you that Hubble look. Tri-color narrowband imaging using these three filters is possible with the Moon up so your imaging gear doesn't have to be sidelined for weeks at a time.


Warranty90 Day Covered By OPT


  • Astrodon 1.25" Ha 5nm filter
  • Plastic case