The Antlia Oxygen III (OIII) 3nm filter is suitable for imaging of Oxygen III emissions from nebulas, planetary nebulas and supernova remnants. The 3nm bandwidth delivers a high transmission at a center wavelength of 500.7nm. The extreme narrowness in bandwidth enables astro-imaging from heavily light polluted locations and delivers improved contrast at darker sites. The filter effectively suppresses interference from other wavelengths, especially artificial mercury and sodium lamps.

Antlia narrowband filters are designed to bring out the faintest features in nebulosity by reducing the unwanted background frequencies – the narrower the filter, the better. Conventional broader narrowband filters cause a heavy loss in transmission due to the strong CWL (Center Wavelength) shift. Antlia's OIII filter is designed to deliver 85% or higher transmission within 1nm of the center at the 500.7nm line which means that the 3nm Pro narrowband filter can guarantee high transmittance for working with both long focal ratios and fast optical systems. Blue-shift data shows that Antlia 3nm Pro filters can be used with nearly all systems as fast as f/3 with minimal loss in emission signal and meets the requirements of fast optics like Hyperstar and RASA.

When Antlia designs filters for astronomy imaging systems, they look at how they will work together with optical systems, carefully designing the blocking and band-pass parameters to achieve an optimum result. The out-of-band blocking specification is rated OD5 (0.001%) which delivers an excellent signal-to-noise ratio and effective cut-off rate to minimize interference from other wavelengths. A sharp cut-off rate is a very important performance index since it is designed to sharply attenuate off-band wavelengths. The result is that the Antlia OIII filter delivers excellent contrast with extremely dark backgrounds whilst delivering a high transmission of the OIII signal. Such filters are more difficult to produce to a consistently high standard. The sharp cut-off also minimizes the effect of halos around stars, although halos may still be visible in some cases around bright stars as detailed above.

In the production process, Antlia uses very strict quality control standards. Each filter is individually tested and scanned to ensure that the product meets their high-performance parameters. The end result is a filter that achieves excellent contrast but with a higher production cost. We believe the price to performance ratio compares more favorably than similar premium filters on the market.

Application and Performance:

    High transmittance and ultra-narrow 3.0 nm bandwidth to maximize contrast.
    Steep spectral profile reduces halos around bright stars.
    Antlia narrowband Pro filters can be used down to f/3 systems with slight loss of signal
    A single substrate to eliminate internal reflections.
    Designed for astronomy imaging in both light polluted and dark sites.
    Extends imaging time when the Moon is up.
    Suitable for imaging of OIII emission in nebulas, planetary nebulas and supernova remnants.
    All Antlia Narrowband filters are edge blackened to minimize interference from stray light.
    Superior optical reliability reduces post image processing.
    This filter is not suited to deep sky objects that do not contain OIII emissions. It can be used to image OIII regions in galaxies and such images can be combined into LRGB images to better highlight the OIII emitting regions of galaxies.
    With the Ha, SII, OIII set of filters (Ha and SII sold separately), you are able to process your images to achieve the impressive Hubble color palette.
    The Ha and OIII filters (Ha sold separately) can be used to achieve great narrowband results using the Bi-Color process.

Technical Data:

    Schott optical substrate
    1.25” mounted (2mm thickness +/-0.05mm). Additional sizes available separately
    FWHM (Full Width at Half Maximum): 3nm
    CWL (Center Wavelength): 500.7nm
    Peak transmission: >85% transmisson at OIII line at 500.7nm
    Blocking: >5 OD (0.001% out of band blocking) @ 300-1000nm
    Surface Quality: Scratch/Dig = 60/40 (Refer to MIL-O-13830)
    2 sides fine-optically polished to ensure accurate 1/4 wavefront
    Less than 30 arcsec parallelism
    2 sides Multi-layers anti-reflection coating
    Single / Non-glued substrate

Warranty:

    3 years against delamination

Filter Ring:

    1.25” Mounted (M28.5x0.6 thread)
    Ultra-thin filter cell to minimize vignetting by maximizing possible clear aperture
    Black Anodized Finish
    Laser Engraving, No Fading

Not Recommended:

    Solar Observing and imaging
    Visual observation
    DO NOT LOOK AT THE SUN WITH ANTLIA FILTERS. Serious eye damage will result if you fail to observe the warning.