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Antlia 7nm Narrowband H-alpha Prime Filter
Antlia 7nm Narrowband H-alpha Prime Filter
Antlia 7nm Narrowband H-alpha Prime Filter
Antlia 7nm Narrowband H-alpha Prime Filter

Antlia 7nm Narrowband H-alpha Prime Filter

by Antlia
SKU ANT-HA-7NM-RD36
CA$221.00 - CA$221.00
CA$221.00
CA$221.00 - CA$221.00
CA$221.00
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  • 7nm Full Width at Half Maximum (FWHM) Bandpass
  • Centered on the 656.3nm Hydrogen-alpha Emission Line
  • Passes NII Emission Lines at 654.8nm and 658.3nm
  • Greater than 90% Peak Transmission
  • OD4 Blocking (>99.99%) of Out-of-Band Wavelengths from 300-1000nm
  • Lambda/4 or Better Transmitted Wavefront
  • Usable with Systems as Fast as f/2 with Minimal Loss of Signal
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  • Description
  • FAQ
  • Specifications
  • Warranty

  • Antlia 7nm Narrowband H-alpha Prime Filter

    The Antlia 7nm Narrowband H-alpha Prime Filter isolates the critical 656.3nm wavelength with a 7nm FWHM bandpass, achieving over 90% peak transmission for maximum signal. By also passing the adjacent NII emission lines at 654.8nm and 658.3nm, this filter is effective for deep-sky objects that contain H-alpha and NII emissions. Its OD4 blocking across the 300-1000nm spectrum delivers an excellent signal-to-noise ratio, and it can be used with nearly all systems as fast as f/2 with minimal loss in emission signal.

    7nm FWHM: Capturing H-alpha and NII at >90% Transmission

    The 7nm bandpass strikes a critical balance between contrast and signal strength. Antlia says the 7nm Prime filters deliver superior SNR and better contrast, and the bandpass is wide enough to pass not only the primary H-alpha line at 656.3nm but also the nearby Nitrogen-II (NII) lines at 654.8nm and 658.3nm. With peak transmission above 90%, it suits the targets Antlia names: H-alpha and NII emission nebulae, planetary nebulae, Wolf-Rayet nebulae such as the Crescent Nebula (NGC 6888), and supernova remnants.

    OD4 Blocking and Lambda/4 Optics for High-Contrast Results

    Signal purity is defined by what a filter rejects. The H-alpha Prime filter provides OD4 blocking from 300nm to 1000nm, blocking more than 99.99% of out-of-band light, which Antlia says delivers an excellent SNR and minimizes interference from other wavelengths. The filter is built on a single, non-glued optical substrate with a Lambda/4 or better transmitted wavefront and parallelism under 30 arcseconds, and its steep spectral profile minimizes halos around bright stars.

    Engineered for Modern Systems Down to f/2

    Fast optical systems present a challenge for narrowband filters due to the steep light cone, which can cause band-shifting and signal loss. Antlia states that, with their wider FWHM, 7nm Prime filters can be used with nearly all systems as fast as f/2 with minimal loss in emission signal.

    Antlia 7nm Prime vs. 3nm Pro: Choosing the Right Bandpass

    The choice between a 7nm and a 3nm filter depends on your equipment and sky conditions. The 7nm Prime suits very fast optical systems, down to f/2, and imagers who want to capture both H-alpha and NII data simultaneously.

    • Choose the 7nm Prime for: Faster signal acquisition, use with systems as fast as f/2, and capturing combined H-alpha and NII detail.
    • Consider a 3nm Pro for: Maximizing contrast in light-polluted areas or extending imaging time when the moon is up. Antlia rates the 3nm Pro series as usable down to f/3.

  • How does the Antlia 7nm H-alpha Prime filter perform on an f/2 system?

    Antlia states that, with their wider FWHM, 7nm Prime filters can be used with nearly all systems as fast as f/2 with minimal loss in emission signal.

    Is the Antlia 7nm H-alpha Prime suitable for the Eagle Nebula (M16)?

    Yes. The 7nm FWHM is wide enough to transmit the H-alpha line at 656.3nm as well as the important NII emission lines at 654.8nm and 658.3nm. The Eagle Nebula is an H-alpha emission nebula, one of the target types Antlia lists for this filter.

    Why is it important that the Antlia 7nm H-alpha Prime filter also passes NII emission lines?

    Antlia lists H-alpha and NII emission nebulae, planetary nebulae, Wolf-Rayet nebulae and supernova remnants as targets. The Antlia 7nm H-alpha Prime FWHM is wide enough to pass both the H-alpha line and the NII lines at 654.8nm and 658.3nm, so it records the combined signal from these objects.

    When should I choose the Antlia 7nm Prime over a 3nm filter?

    Choose the Antlia 7nm Prime filter if you are using a very fast optical system (Antlia rates it for systems as fast as f/2) or want to gather signal more quickly. A 3nm filter offers higher contrast from its narrower bandpass, at the cost of longer exposures; Antlia rates its 3nm Pro series as usable down to f/3.

    Can I use the Antlia 7nm H-alpha Prime filter for visual observing?

    No. Antlia lists night visual observation as not recommended for this filter. It is designed for astrophotography of deep-sky objects that contain H-alpha and NII emissions.

    How does the Antlia 7nm H-alpha Prime filter minimize halos around bright stars?

    Antlia attributes this to three points on the Antlia 7nm H-alpha Prime: a steep spectral profile that minimizes halos around bright stars, a single, non-glued substrate to eliminate internal reflections, and edge blackening of unmounted filters to eliminate internal reflections from stray light.

  • Filter Type H-alpha narrowband (7nm Prime series)
    Central Wavelength (CWL) 656.3nm
    Bandpass (FWHM) 7nm
    Peak Transmission >90%
    Additional Lines Passed NII at 654.8nm and 658.3nm
    Blocking >OD4 (0.01%) @ 300-1000nm
    Recommended F-Ratio Usable with systems as fast as f/2 with minimal loss of signal
    Transmitted Wavefront Lambda/4 or better
    Parallelism < 30 arcseconds
    Substrate Optical, single / non-glued substrate
    Surface Quality 60/40 (scratch/dig) per MIL-O-13830
    Filter Thickness 2mm +/-0.05mm (36mm unmounted)
    Edge Treatment Unmounted filters are edge blackened
    Available Sizes 36mm Round Unmounted
    Not Recommended For Solar imaging, night visual observation
    Warranty 3-years against delamination

  • This product is covered by the Antlia 3-Year Warranty against delamination.