Antlia SII 4.5 nm EDGE Filter 2 inch Mounted

Antlia SII 4.5 nm EDGE Filter 2 inch Mounted

Description

The Antlia SII 4.5 nm EDGE filter is a narrowband imaging filter for deep-sky astrophotography of nebulae emitting in the sulfur II (SII) line at 672.4 nm. With a 4.5 nm FWHM bandpass and OD5 out-of-band blocking, it achieves more than 90 % transmission across the central wavelength.
The filter design, derived from the Antlia 3 nm Pro series, delivers superior signal-to-noise ratio and outstanding image contrast. Its steep spectral profile minimizes halos around bright stars, while the single non-glued substrate eliminates internal reflections.
The filter’s edge is blackened to prevent stray light, providing stable spectral performance even with fast optical systems down to f/3. Antlia EDGE filters offer excellent optical reliability and are ideal for long-exposure imaging under light-polluted or moonlit conditions.
This filter is intended solely for astrophotography of SII emission nebulae and must not be used for solar or visual observation.

Technical Specifications

• Manufacturer: Antlia

• Product: SII 4.5 nm EDGE Filter 2 inch mounted

• Type: narrowband SII filter

• Central wavelength (CWL): 672.4 nm

• Full width at half maximum (FWHM): 4.5 nm

• Peak transmission: > 90 %

• Out-of-band blocking: OD5 (300–1000 nm)

• Optical substrate: single, non-glued

• Filter thickness: 2 mm ± 0.05 mm

• Surface quality: 60/40 (MIL-O-13830)

• Transmitted wavefront: λ/4 or better

• Parallelism: < 30 arcsec

• Filter mount: 2 inch (M48 x 0.75)

• Clear aperture: 48 mm

• Net weight: approx. 0.01 kg

• Application: astrophotography of SII emission objects

• Not recommended: solar imaging, visual observation