The Antlia OIII 3nm Pro narrowband filter features a finely tuned 3nm Full Width at Half Maximum (FWHM), which boosts the signal-to-noise ratio by significantly reducing background light and enhancing contrast in emission nebulae. Designed for astrophotography, this filter provides a peak transmission of over 85% at the critical [OIII] emission line of 500.7nm, ensuring maximum signal capture and well-defined nebular structure.

Unlike conventional wider-band filters that suffer from significant transmission loss due to center wavelength (CWL) shifts, the Antlia 3nm Pro filter maintains high transmission (T > 85%) within ±1nm of the central bandwidth. This stability enables consistent performance across a range of optical systems, from long focal ratios to fast imaging setups.

Independent testing confirms that the filter exhibits minimal blue-shift even at fast focal ratios down to f/3, making it fully compatible with fast optics such as HyperStar and RASA systems, with negligible loss of emission signal.

With an out-of-band blocking specification of OD5 (0.001%), the filter effectively suppresses unwanted light from other wavelengths, delivering excellent signal-to-noise performance.

Additionally, the sharp cut-off profile, precisely engineered for performance, actively reduces halo artifacts around bright stars and delivers cleaner, higher-contrast images.

Application and Performance:

• High transmittance with ultra-narrow 3nm bandwidth to maximise contrast and isolate emission lines.
• Steep spectral profile –  minimises halos and glare around bright stars.
• Precision-ground single substrate – construction eliminates internal reflections and ensures optimal image clarity.
• Ideal for capturing OIII-rich targets –  such as emission nebulae, planetary nebulae, Wolf-Rayet nebulae, and supernova remnants.
• Effective in both light-polluted environments and dark-sky locations, offering imaging flexibility.
• Extends useful imaging time  during bright lunar phases by effectively rejecting moonlight interference.
• Compatible with fast optical systems down to f/3, with only minimal signal loss—suitable for setups like RASA and HyperStar.
• Edge-blackened filter housing eliminates internal reflections caused by stray light for improved contrast.
• Exceptional optical reliability minimises the need for extensive post-processing.

NOTE – This filter is not recommended for deep sky objects that lack Oiii emission lines.