The Antlia H-alpha 3nm Pro narrowband filter features a precisely tuned Full Width at Half Maximum (FWHM) of 3nm, effectively increasing contrast by suppressing unwanted background light and enhancing detail in emission nebulae. With a peak transmission of 88% at the 656.3nm wavelength, this filter captures maximum signal for well-defined nebular structures.

Unlike broader narrowband filters that suffer from significant transmission loss due to centre wavelength (CWL) shift, Antlia’s 3nm Pro design ensures T>88% within ±1nm of the central bandpass. This consistency in performance makes it well-suited to both long focal ratio telescopes and fast optical systems, including setups down to f/3, with only minimal signal degradation.

Testing confirms that even at fast focal ratios, the filter maintains high transmission with minimal blue-shift loss, meeting the demands of high-speed imaging systems.

An out-of-band blocking level of OD5 (0.001%) ensures excellent signal-to-noise ratio (SNR), delivering clean data by eliminating interference from nearby wavelengths. Additionally, the filter’s sharp cut-off profile reduces halo artifacts around bright stars, making it an ideal choice for high-contrast astrophotography.

Application and Performance:

• Delivers high transmittance with an ultra-narrow 3nm bandwidth to maximise contrast and isolate H-alpha emission lines

• Features a steep spectral profile that significantly reduces halos around bright stars

• Constructed from a single optical substrate to eliminate internal reflections and enhance image clarity

• Optimised for H-alpha-rich targets including emission nebulae, planetary nebulae, Wolf-Rayet nebulae, and supernova remnants

• Performs reliably in both light-polluted urban environments and pristine dark-sky locations

• Enables extended imaging sessions even during bright moon phases by rejecting unwanted moonlight

• Maintains strong signal integrity in fast optical systems down to f/3, such as RASA and HyperStar setups

• All unmounted Antlia narrowband filters feature edge-blackened coatings to suppress stray light reflections

• Offers outstanding optical reliability, minimising the need for heavy post-processing

• Note: Best suited for deep-sky objects that emit strongly in the H-alpha wavelength