Antlia ALP-T Dual Band 3 nm SII/H-beta Highspeed Filter 2" (Antlia) is a dual-band narrowband filter designed for emission nebula astrophotography with fast optical systems. It enables the simultaneous capture of ionised sulphur SII and hydrogen H-beta emission. The Highspeed version uses pre-shifted transmission bands that reduce signal loss caused by blueshift occurring at large angles of incidence.

Key features

• two narrow transmission bands with a nominal FWHM of 3 nm for the SII and H-beta lines
• simultaneous capture of ionised sulphur SII and hydrogen H-beta signals
• Highspeed version designed for fast optical systems
• pre-shifted transmission bands compensating for blueshift caused by a large angle of incidence
• construction developed primarily for use with OSC colour astronomy cameras
• suitable for use with monochrome cameras as a dual-band luminance filter
• reduction of artificial light, moonlight and atmospheric airglow in the captured data
• improved contrast of nebular structures and signal-to-noise ratio
• ability to supplement Ha/OIII filter data with SII and H-beta channels when creating multi-channel compositions
• multi-layer coatings on both sides and anti-reflection coatings reducing internal reflections and halo formation

Set contents

• Antlia ALP-T Dual Band 3 nm SII/H-beta Highspeed Filter 2"

Technical specifications

• filter type: dual-band narrowband astrophotography filter
• version: Highspeed with pre-shifted transmission bands
• transmitted emission lines: SII and H-beta
• nominal SII line wavelength: 672.4 nm
• nominal H-beta line wavelength: 486.1 nm
• nominal SII FWHM bandwidth: 3.5 nm
• nominal H-beta FWHM bandwidth: 3.5 nm
• primary compatibility: OSC colour astronomy cameras
• additional compatibility: monochrome cameras
• optical application: fast astrophotography systems
• application: emission nebula imaging
• cell size: 2"
• cell thread: M48 × 0.75
• cell finish: black anodising and laser markings
• suitable for visual observation: no
• suitable for solar imaging: no

The Antlia ALP-T Dual Band 3 nm SII/H-beta Highspeed Filter enables the simultaneous capture of two complementary emission bands and, when combined with an Ha/OIII filter, expands colour-camera data with SII and H-beta signals.