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Antlia ALP-T Dual Band Ha&OIII 3nm

Antlia ALP-T Dual Band Ha&OIII 3nm

by Antlia
SKU ANT-ALP-T-3NM-HAOIII
CA$554.00 - CA$554.00
CA$554.00
CA$554.00 - CA$554.00
CA$554.00
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  • Passes H-alpha (656.3nm) and OIII (500.7nm) emission lines
  • 3nm (+0.6/-0.1nm) FWHM on both lines
  • Peak transmission of 90% (H-alpha) and 82% (OIII)
  • ≥OD4.5 blocking from 300-1100nm; designed for Bortle 1 to 8 skies
  • Best performance with optics slower than f/4; 2" mounted, male M48x0.75 thread
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Antlia ALP-T Dual Band Ha&OIII 3nm Filter

    The Antlia ALP-T Dual Band Ha&OIII 3nm Filter captures the two main emission wavebands, H-alpha at 656.3nm and OIII at 500.7nm simultaneously through a single filter. It has a 3nm bandpass on both lines and ≥OD4.5 blocking from 300-1100nm. With peak transmission rates of 90% for H-alpha and 82% for OIII, this 2mm thick filter is made primarily for color cameras on optics slower than f/4.

    3nm Dual-Bandpass: Isolating Ha at 656.3nm and OIII at 500.7nm

    This filter's primary function is to capture the specific wavelengths of light emitted by ionized hydrogen (H-alpha at 656.3nm) and doubly ionized oxygen (OIII at 500.7nm). By restricting the incoming light to an extremely narrow 3nm full width at half maximum (FWHM), the filter increases the contrast between the nebula and the sky background.

    Peak transmission is 90% for the red H-alpha line and 82% for the blue-green OIII line, and both are captured in the same exposure.

    OD4.5 Blocking from 300-1100nm for Bortle 1-8 Skies

    The filter provides optical density (OD) 4.5 blocking, which attenuates unwanted wavelengths by a factor of over 30,000. This suppression is effective across a vast range from 300nm to 1100nm, covering common sources of light pollution, moonlight, and natural airglow.

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

    Advanced Coatings and Lambda/4 Substrate for Halo Suppression

    Antlia employs an Ion Gun Assisted Deposition coating process and says its coating technology makes durability very reliable. These advanced multi-layer coatings are applied to a single, non-glued optical substrate with a surface quality of 60/40 scratch/dig (MIL-O-13830) and a transmitted wavefront of Lambda/4 or better.

    • Halo Suppression: Antlia uses a halo suppression anti-reflective coating to minimize halos and internal reflections.
    • Flat-Top Profile: The filter's bandpass has an "ideal flat-top" shape, with a moderate bandpass that reduces spectrum downshifts.
    • Parallelism: Less than 30 arcseconds.

    Imaging Slower than f/4: Color and Monochrome Camera Strategy

    The filter is recommended for optics slower than f/4 for best performance. In faster systems, the steep light cone can cause a shift in the filter's bandpass, potentially reducing transmission. For optics faster than f/4, a pre-shifted highspeed version is a better choice.

    While designed primarily for one-shot color (OSC) cameras, the filter can be used as a luminance filter with monochrome cameras to save imaging time. The two lines are recorded together and cannot be separated afterwards.

    The 4-Channel Workflow: Pairing with the SII & H-beta Filter

    When paired with the Antlia ALP-T Dual Band SII & Hb filter, you can capture all four major emission nebula wavelengths (Ha, OIII, SII, Hb) using only two filters.

    After capturing data with both filters, the channels can be separated and recombined to create a variety of false-color palettes, such as the popular S-H-O "Hubble" palette or more creative combinations like H-O-Hb. Antlia adds that the data can be used for luminance contrast enhancement of traditional RGB-balanced images.

  • What kind of targets suit the Antlia ALP-T Ha&OIII filter?

    Emission nebulae that emit in both Hydrogen-alpha and Oxygen-III, such as the Orion Nebula (M42), the Lagoon Nebula (M8) and the Veil Nebula. The filter records the red hydrogen and blue-green oxygen emission in the same exposure.

    Can I use the Antlia ALP-T 3nm filter with my f/4 telescope?

    The filter is recommended for systems slower than f/4 for the best performance. f/4 sits at that limit. For optics faster than f/4, a pre-shifted highspeed version is a better choice.

    How does the Antlia ALP-T Ha&OIII filter work with a color camera?

    With a one-shot color (OSC) camera, the filter passes the red H-alpha (656.3nm) and blue-green OIII (500.7nm) light to the sensor's red, green, and blue pixels. This lets you capture two narrowband channels at once, creating a high-contrast color image of a nebula while blocking out light pollution, all in a single set of exposures.

    Is the Antlia ALP-T filter suitable for imaging galaxies or reflection nebulae?

    No, this is not the right filter for broadband targets. Galaxies like Andromeda (M31) and reflection nebulae like the Pleiades (M45) shine by reflecting starlight, which is a continuous spectrum. The 3nm bands block almost all of that light, so the filter is meant for emission nebulae.

    Why can't I use the Antlia ALP-T filter for visual observation?

    Night visual observation is not recommended; the filter is made for imaging with a camera.

    What is the difference between this filter and Antlia's SII & H-beta filter?

    This filter captures H-alpha (656.3nm) and OIII (500.7nm). Its sibling filter captures Sulfur-II (SII) and Hydrogen-beta (Hb). They are designed to be used together with a color camera to capture all four key narrowband channels, allowing you to create false-color images like the S-H-O Hubble palette.

  • Filter Type Dual-band (H-alpha / OIII)
    Central Wavelength (CWL) 656.3nm (H-alpha) / 500.7nm (OIII)
    FWHM 3nm +0.6/-0.1nm
    Peak Transmission 90% (H-alpha) / 82% (OIII)
    Blocking ≥OD4.5 @ 300-1100nm
    Filter Thickness 2mm +/-0.05mm
    Substrate Optical, single / non-glued substrate
    Surface Quality (S/D) 60/40 (MIL-O-13830)
    Transmitted Wavefront Lambda/4 or better
    Parallelism less than 30 arcsec
    Recommended F-Ratio Slower than f/4 for best performance
    Filter Ring 2" mounted, M48x0.75 thread
    Not Recommended For Solar imaging, night visual observation

    • Antlia ALP-T Dualband 3nm Ha&OIII filter, 2" mounted

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    • Protective case

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  • Contact us for warranty details.