The Antlia SII 7nm Prime narrowband filter delivers a 7nm FWHM (Full Width at Half Maximum) bandpass, striking a strong balance between high signal transmission and background suppression. Antlia incorporates the same advanced optical coatings used in its 3nm Pro series, allowing the 7nm Prime filters to achieve excellent contrast and a superior signal-to-noise ratio in your images.

Engineered for precision, this filter transmits 90% at the central wavelength of 672.4nm and captures the critical SII emission lines at 671.6nm and 673.1nm. You can rely on it to bring out faint sulfur-rich structures in nebulae with clarity and detail.

With OD4 (0.01%) out-of-band blocking, the filter effectively cuts off unwanted wavelengths, reducing interference and preserving signal purity. Its steep spectral profile also minimizes halos around bright stars, ensuring crisp results.

Antlia designed this filter to work with nearly all imaging systems, including fast optical setups down to f/2, without significant signal loss. Whether you’re imaging from a dark site or under light-polluted skies, the SII 7nm Prime filter helps you reveal deep-sky objects with strong SII emissions—sharply and cleanly.

Application and Performance:

• Transmits 90% of light at the central wavelength of 672.4nm for strong SII signal capture

• Passes key SII emission lines at 671.6nm and 673.1nm to reveal fine nebular structure

• Handles fast optics down to f/2 with minimal signal loss, making it ideal for wide-field imaging systems

• Reduces halos around bright stars with a steep and well-controlled spectral profile

• Uses a single optical substrate to eliminate internal reflections and preserve image clarity

• Targets SII-rich deep-sky objects, including emission nebulae, planetary nebulae, Wolf-Rayet regions, and supernova remnants

• Performs well in both light-polluted environments and dark-sky locations

• Features edge-blackened construction to block stray light and prevent internal reflections

• Delivers high optical stability and consistency, reducing the need for extensive post-processing

• Enhances contrast and structure in targets emitting in the SII wavelength range

Not recommended for:

• Solar imaging

• Visual observation at night