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Antlia ALP-T Dualband 5nm SII/Hb Filter

Antlia ALP-T Dualband 5nm SII/Hb Filter

by Antlia
SKU ANT-ALP-T-SII-HB-2
$350.00 USD - $350.00 USD
$350.00 USD
$350.00 USD - $350.00 USD
$350.00 USD
Price Match Policy!
  • Dual-bandpass 5nm design for one-shot color (OSC) cameras
  • Passes Sulfur-II (672.4nm) and Hydrogen-Beta (486.1nm) emission lines
  • Peak transmission of 90% for SII and 85% for H-Beta
  • Greater than OD4.5 blocking of unwanted wavelengths and light pollution
  • 2" mounted, male M48x0.75 thread, ultra-thin cell
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Antlia ALP-T Dualband 5nm SII/Hb Filter

    The Antlia ALP-T Dualband 5nm SII/Hb Filter is engineered to capture two key emission lines simultaneously, passing Sulfur-II at 672.4nm and Hydrogen-Beta at 486.1nm. It achieves a peak transmission of 90% for the deep red SII line and 85% for the blue H-Beta line, each isolated within a tight 5nm full width at half maximum (FWHM) bandpass. Designed for light pollution suppression from Bortle 1 to Bortle 8 skies, the filter provides ≥OD4.5 blocking of unwanted wavelengths and cuts near-infrared light up to 1100nm, enabling high-contrast nebula imaging with color cameras.

    Dual 5nm Bandpasses: 90% Transmission at 672.4nm and 85% at 486.1nm

    This filter's design targets two specific wavelengths to add depth and structural detail to your nebula images. The Sulfur-II signal, centered at 672.4nm, records information from the deep red end of the spectrum, often revealing ionized structures distinct from Hydrogen-alpha. The Hydrogen-Beta band at 486.1nm captures the second most common hydrogen emission after H-alpha. It can reveal structures not seen in OIII, in nebulae that contain some blue emission.

    With a narrow 5nm FWHM on both lines and peak transmission rates of 90% (SII) and 85% (H-Beta), the target's signal is strongly prioritized over background skyglow. Nebulae are recorded with greater contrast against the background than without the filter.

    The 4-Channel System: Pairing the Antlia SII/Hb and Ha/OIII Filters

    The primary application for the ALP-T SII/Hb filter is in tandem with its sibling, the Antlia ALP-T 5nm Ha&OIII filter. Capturing data with both filters allows you to acquire signals from all four major emission lines (Ha, OIII, SII, Hb) using a single one-shot color camera. This quad-band approach creates a complete narrowband dataset from which you can separate the channels in post-processing.

    This workflow gives you the flexibility to assemble images in various false-color palettes, such as S-H-O, or create custom combinations like H-O-Hb to emphasize specific structures.

    OD4.5 Blocking for Bortle 1-8 Light Pollution

    An Ion Gun Assisted Deposition (IAD) coating process on a double-sided polished 2mm substrate achieves an extremely steep, flat-top bandpass. Suppression of unwanted wavelengths from light pollution, moonlight and airglow is rated at OD4.5 or greater.

    Near-infrared is blocked up to 1100nm. Antlia designed the filter to suppress artificial lighting from Bortle 1 to Bortle 8.

    The H-Beta Advantage: Why Pair SII with 486.1nm Instead of OIII?

    The pairing is partly explained by the sensor. Most OSC camera sensors use an RGGB Bayer pattern with twice as many green pixels as red or blue, which already gives better capture of the blue-green OIII line. The companion Ha/OIII filter already captures this signal efficiently.

    Adding H-Beta provides new information from the blue part of the spectrum, revealing structures that OIII might not show. While a dedicated monochrome SII filter can give a slightly cleaner SII signal, the dual-band SII/Hb design provides two channels of data in a single exposure. This provides a distinct improvement in nebula contrast and improved feature separation in H-beta areas that would otherwise be lost.

  • How does the Antlia ALP-T 5nm SII/Hb filter work with a color camera?

    The Antlia ALP-T 5nm SII/Hb is a dual line-pass filter designed specifically for color (OSC) cameras. It isolates two specific wavelengths: the deep red Sulfur-II (672.4nm) and the blue Hydrogen-Beta (486.1nm). When you capture an image, the red pixels record mainly the SII line and the blue pixels mainly the H-Beta line. This allows you to separate these signals during post-processing to create false-color images.

    Which nebulae are good targets for the Antlia ALP-T SII/Hb filter?

    This filter is designed for emission nebulae that are rich in both sulfur and hydrogen-beta. It is ideal for nebulae that emit in the sulfur and H-Beta range, and H-Beta can reveal structure in nebulae with some blue emission that Ha, SII and OIII filters do not capture.

    Can I use the Antlia ALP-T 5nm SII/Hb filter from my Bortle 8 city balcony?

    Yes. The Antlia ALP-T is engineered for effective light pollution suppression in environments from Bortle 1 to Bortle 8. Its 5nm bandpasses and ≥OD4.5 blocking let only light close to the SII and H-Beta lines reach the sensor.

    Why use the Antlia SII/Hb filter instead of just a monochrome SII filter with my OSC camera?

    While a monochrome SII filter might provide the cleanest possible SII signal, the Antlia SII/Hb filter offers a significant advantage for OSC users by capturing two channels (SII and H-Beta) simultaneously in a single exposure. The H-Beta data provides unique structural information from the blue part of the spectrum that a simple SII filter would miss entirely, adding more depth and detail to the final image.

    Do I need the Antlia ALP-T Ha&OIII filter to use the SII/Hb filter?

    While not strictly required, the Antlia SII/Hb filter is designed to be used as part of a system with the Antlia ALP-T 5nm Ha&OIII filter. Using them together allows you to capture all four major narrowband emission lines (Ha, OIII, SII, Hb) with your OSC camera. This provides a complete dataset for full false-color processing. Using the SII/Hb filter alone will only give you two of the four key datasets.

    Can I use the Antlia ALP-T 5nm SII/Hb filter with a monochrome camera?

    Yes, it can be used as a narrowband filter for monochrome cameras. However, because a monochrome sensor cannot distinguish between the two wavelengths, it will record both the SII and H-Beta light together in a single grayscale image. The two signals cannot be separated afterwards; this use saves imaging time.

  • Filter Type Dual-band (dual line-pass), ALP-T 5nm Series
    Available Sizes 2" Mounted
    Sulfur-II Bandpass CWL 672.4nm, FWHM 5nm
    Sulfur-II Transmission 90% (peak)
    Hydrogen-Beta Bandpass CWL 486.1nm, FWHM 5nm
    Hydrogen-Beta Transmission 85% (peak)
    Blocking ≥OD4.5 on unwanted wavelengths
    NIR Blocking Up to 1100nm
    Filter Thickness 2mm ±0.05mm
    Filter Ring 2" (M48x0.75), ultra-thin, black anodized
    Coating Technology Ion Gun Assisted Deposition
    Substrate Double-sided polished
    Spectrum Shape Flat-top with extremely steep bandpass
    Recommended Cameras DSLR, CMOS, and CCD color (OSC) cameras
    Monochrome Use Can be used as a narrowband filter with monochrome cameras
    Light Pollution Suppression Effective from Bortle 1 to Bortle 8
    Recommended Pairing Antlia ALP-T Dual Band 5nm Ha&OIII filter
    Not Recommended For Solar imaging, night visual observation

    • Antlia ALP-T Dualband 5nm SII/H-beta filter, 2" mounted

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    • Protective case

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  • Contact us for warranty details.