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Antlia 3nm Narrowband NII Pro Filter - 2"
Antlia 3nm Narrowband NII Pro Filter - 2"
Antlia 3nm Narrowband NII Pro Filter - 2"
Antlia 3nm Narrowband NII Pro Filter - 2"

Antlia 3nm Narrowband NII Pro Filter - 2"

by Antlia
SKU ANT-NII-3NM-2
CA$553.00 - CA$553.00
CA$553.00
CA$553.00 - CA$553.00
CA$553.00
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  • Isolates the Nitrogen-II (NII) emission line at 654.8nm
  • 3nm bandpass (FWHM)
  • 88% peak transmission
  • Greater than OD5 out-of-band blocking from 300-1100nm
  • Usable down to f/3 with minimal loss of signal
  • Lambda/4 or better transmitted wavefront on a 2mm thick substrate
  • 2" mounted, male M48x0.75 thread
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Antlia 3nm Narrowband NII Pro Filter - 2"

    The Antlia 3nm Narrowband NII Pro Filter has a 3nm bandpass centred on 654.8nm, a nitrogen-II (NII) emission wavelength, with 88% peak transmission and out-of-band blocking greater than OD5 across 300-1100nm. It is built on a single, non-glued 2mm substrate with a transmitted wavefront of Lambda/4 or better, and the narrowband Pro filters can be used down to f/3 with minimal loss of signal.

    Isolating the 654.8nm NII Line with a 3nm Bandpass

    The 3nm bandpass is centred on 654.8nm. As the bandwidth narrows, these 3nm Pro filters enhance the contrast of emission targets by reducing unwanted background signal. The filter can be used in light-polluted areas and at dark sites, and it extends imaging time when the moon is up.

    Its targets are NII emission nebulae, and the filter is only effective for deep-sky objects that contain NII emission. NII is not one of the three channels of the SII/Ha/OIII palette.

    88% Peak Transmission and >OD5 Blocking

    Peak transmission is 88% at 654.8nm, and out-of-band blocking is rated greater than optical density (OD) 5.

    An OD5 rating means the filter attenuates unwanted light from 300nm to 1100nm by a factor of 100,000 (transmitting only 0.001%). This ensures an excellent signal-to-noise ratio (SNR) and effective cutoff rates that minimize interference from other wavelengths.

    Lambda/4 Wavefront on a Single 2mm Substrate

    The filter is built on a single, non-glued 2mm optical substrate, which eliminates internal reflections. Its steep spectral profile minimizes halos around bright stars.

    • Transmitted Wavefront: Lambda/4 or better.
    • Parallelism: Less than 30 arcseconds.
    • Surface Quality: 60/40 scratch/dig per MIL-O-13830.

    Engineered for Fast Optical Systems Down to f/3

    In fast telescopes the steeper light cone shifts a narrowband filter's central wavelength toward shorter wavelengths (blue shift). All Antlia narrowband Pro filters can be used down to f/3 with minimal loss of signal.

    Antlia 3nm NII Pro vs. Wider Narrowband Filters

    A 3nm band passes less skyglow and moonlight around the line than a 5nm or 7nm band, so the background is darker.

    2" Ultra-Thin Cell with M48x0.75 Threads

    The 2" cell screws in by a male M48x0.75 thread. It is ultra-thin and black anodized, with laser engraving.

  • What is the Antlia 3nm NII Pro filter used for in astrophotography?

    The Antlia 3nm NII Pro is a specialized narrowband filter designed to capture light from the Nitrogen-II (NII) emission line at 654.8nm. Its targets are NII emission nebulae, and the filter is only effective for objects that contain NII emission.

    How does the Antlia 3nm NII Pro perform in a fast telescope like an f/4 Newtonian?

    The narrowband Pro filters are usable down to f/3 with minimal loss of signal, and f/4 is slower than that.

    Can I use the Antlia 3nm NII Pro filter for visual observation?

    No. Antlia explicitly states this filter is not recommended for night visual observation. It is meant for astrophotography.

    What is the advantage of the Antlia NII Pro's 3nm bandpass over a wider 7nm filter?

    A 3nm band passes less background light around the line than a 7nm band, so the background is darker, which matters most under light pollution or moonlight.

    Does the 2mm thickness of the Antlia 3nm NII Pro filter require refocusing?

    The Antlia 3nm NII Pro filter has a specified thickness of 2mm +/- 0.05mm. Antlia makes no parfocal claim, so check focus after a filter change.

    What does >OD5 out-of-band blocking mean for the Antlia 3nm NII Pro?

    OD5 stands for Optical Density 5. It means no more than 0.001% of light outside the band gets through, from 300nm to 1100nm. This ensures an excellent signal-to-noise ratio.

    Will the Antlia 3nm NII Pro filter show halos around bright stars?

    The steep spectral profile minimizes halos around bright stars and the single, non-glued substrate eliminates internal reflections. Very bright stars can still show some halo.

    Can I use NII data from the Antlia 3nm Pro in a standard Hubble Palette (SHO) image?

    No, the traditional Hubble Palette uses SII (Sulfur-II), H-alpha, and OIII (Oxygen-III) data mapped to Red, Green, and Blue, respectively. NII is a different emission line. It can serve as an additional channel in your own palette.

  • Filter Type NII Narrowband (3nm Pro series)
    Central Wavelength (CWL) 654.8nm
    Bandpass (FWHM) 3nm
    Peak Transmission 88%
    Out-of-Band Blocking >OD5 (0.001%) @ 300-1100nm
    Recommended f-ratio Usable down to f/3 with minimal loss of signal
    Filter Thickness 2mm +/- 0.05mm
    Substrate Single, non-glued optical substrate
    Transmitted Wavefront Lambda/4 or better
    Parallelism < 30 arcseconds
    Surface Quality 60/40 (MIL-O-13830)
    Size 2" Mounted
    Filter Ring 2" (M48x0.75), ultra-thin black anodized cell, laser engraved
    Not Recommended For Solar imaging, night visual observation

    • Antlia 3nm NII Pro filter, 2" mounted

      × 1

    • Protective case

      × 1

  • Antlia 3-year warranty against delamination.