The Antlia ALP-T Dual Band 5nm SII&H-beta is a 2" mounted dual line-pass filter for one-shot colour (OSC) cameras. It transmits the Sulfur‑II (SII) emission at 672.4 nm and the Hydrogen‑Beta (Hβ) emission at 486.1 nm with narrow 5 nm FWHM bandpasses, improving contrast of nebulae that emit in these wavelengths and enabling multi-channel narrowband workflows with OSC sensors.
Why use this filter
This dual-band design complements Antlia's ALP-T Ha&OIII filter to provide four narrow spectral channels (Ha / OIII / SII / Hβ) when used together. Capturing SII and Hβ can reveal structures and contrast not always apparent with OIII or Ha alone, and is useful for constructing false-colour palettes or for adding luminance contrast to RGB data.
Optical and coating highlights
- Very narrow 5 nm FWHM bandpasses centred on 672.4 nm (SII) and 486.1 nm (Hβ).
- High peak transmission (manufacturer-stated values) and strong out-of-band blocking (≥ OD4.5) to suppress light pollution and airglow.
- Double-sided multi-coatings and ion‑assisted deposition on a polished substrate to maintain bandpass stability.
- Near‑IR blocked to the manufacturer-specified limit (up to 1100 nm).
Use cases
- OSC astrophotography for emission nebulae that include SII and Hβ features.
- Paired with Antlia ALP-T Ha&OIII dual band filter to create four-channel narrowband datasets for false-colour combinations.
- Narrowband imaging where improved signal-to-noise and background suppression are needed.
Important safety and usage notes
- Not for solar imaging; do not use for visual solar observation. Serious eye injury can result.
