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Astrodon 5 nm OIII Narrowband Filter - 49.7 mm Square Unmounted - OIII5-50S

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SKU: ASD-OIII5-50S

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 5 nm Narrowband Filter Highlights

  • Guaranteed 90%+ maximum transmission for the highest achievable performance
  • 5 nm bandwidth
  • >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 5 nm OIII Narrowband Filter

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.

Astrodon Narrowband Filters - Additional Information

Astrodon Narrowband filters set a new standard for imaging and research performance and durability. These filters enhance contrast in emission line objects via narrow 5 nm and 3 nm bandwidths. With a transmittance guaranteed to be above 90% at the emission wavelength, these filters offers the highest signal available. This guarantee combined with a spectrally narrow bandwidth ensures maximum contrast. As a matter of fact, the latest narrowband filters from Astrodon typically achieve a transmittance of between 95 and 98%. Even when taking exposures common to narrowband astrophotography, typically 30-45 minutes in length, these Astrodon Narrowband filters still have the ability to keep halos around bright stars at a minimum, a feature for which these filters are renowned. Finally, these filters are edge-blackened with hard-oxide coatings from edge to edge to eliminate the chance that an uncoated border will cause light leakage. This is critical to keeping stray light to a minimum for a filter that blocks all light save for the narrow bandpass.

With Astrodon Narrowband filters, it's all about the enhanced contrast. The better the contrast, the more the fainter characteristics of celestial objects are highlighted. This improves with filters that have narrower bandwidths. However, maintaining a constant signal (%T at the emission line) as the filter gets spectrally narrower can be difficult. This is what makes Astrodon's >90%T guarantee so critical as it assures that you'll be able to benefit from the enhanced contrast provided by narrower filters.

Main image may not depict the exact filter you will receive.