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July 1st: Store will be closed for Canada Day. Orders placed that day will ship on July 2nd.
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII
ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII

ZWO Narrowband Filter Set - 7nm H-alpha, OIII & SII

by ZWO
SKU ZWO-NB7nm1.25
$369.00 - $699.00
$369.00
$369.00 - $699.00
$369.00
Price Match Policy!
  • Includes 1.25" H-alpha, OIII, and SII filters
  • 7nm bandpass for high-contrast imaging
  • Ideal for creating "Hubble Palette" images
  • Fine-optically polished to 1/4 wave accuracy
  • Up to 80% light transmission
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  • Description
  • FAQ
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  • Warranty

  • ZWO 1.25" Narrowband Filter Set - 7nm H-alpha, OIII & SII

    The ZWO 1.25" Narrowband Filter Set isolates the three most critical emission lines for deep-sky astrophotography with a tight 7nm bandpass. This set includes filters for Hydrogen-alpha (H-a) at 656nm, doubly-ionized Oxygen (OIII) at 500nm, and singly-ionized Sulfur (SII) at 672nm. Each filter is fine-optically polished to 1/4 wave accuracy and features multi-layer anti-reflection coatings to achieve up to 80% light transmission, ensuring maximum signal reaches your monochrome camera sensor.

    Isolating Nebulosity with a 7nm Bandpass

    A 7nm bandpass is the key to high-contrast nebula imaging, especially from light-polluted locations. By transmitting only a razor-thin slice of the spectrum around the target emission line, these filters reject broadband light from streetlights, moonlight, and the general skyglow background. The result is a dramatic increase in contrast, revealing faint, intricate structures in emission nebulae like the Veil Nebula (NGC 6960) or the Heart Nebula (IC 1805) that would be invisible in a standard LRGB image.

    Create Hubble Palette Images with 656nm, 500nm, and 672nm Filters

    This specific combination of H-a, OIII, and SII filters is the foundation of the iconic "Hubble Palette." By mapping the data from each filter to a different color channel (typically SII to red, H-a to green, and OIII to blue), you can create vibrant, scientifically informative images that reveal the chemical composition of a nebula. The 672nm SII filter traces the coolest ionized gas, the 656nm H-a filter captures the most abundant hydrogen, and the 500nm OIII filter highlights the hottest, most energetic regions, giving your images incredible depth and color separation.

    Optical Precision: 1/4 Wave Polish and 80% Transmission

    Image quality is maintained by polishing each filter to a 1/4 wave standard, ensuring the wavefront from your telescope's optics passes through without distortion, preserving star sharpness. With light transmission peaking at 80% within the narrow 7nm bandpass, the filters capture a strong signal from nebulae without requiring excessively long sub-exposure times. This balance makes the ZWO 7nm set a highly efficient choice for capturing deep-sky data.

    ZWO 7nm vs. Tighter 3nm Bandpass Filters

    When choosing narrowband filters, a common question is the ideal bandpass. While more expensive 3nm filters offer slightly higher contrast and even better rejection of light pollution, the ZWO 7nm filters present a more practical starting point for many imagers.

    • Exposure Time: The 7nm bandpass allows more light through, enabling shorter sub-exposures to achieve a comparable signal-to-noise ratio. This is a significant advantage for those with entry-level mounts or limited imaging time.
    • System Compatibility: Tighter filters can sometimes introduce artifacts or be less effective with very fast optical systems (f/4 and below) without careful setup. The 7nm bandpass is more forgiving across a wider range of telescope focal ratios.
    • Cost-Effectiveness: For imagers moving from LRGB or one-shot color, the 7nm set delivers the vast majority of the benefits of narrowband imaging at a more accessible price point.

  • Can I use the ZWO 7nm Narrowband filter set with a color camera?

    Narrowband filters are designed for monochrome cameras. A color camera has a Bayer matrix (a grid of red, green, and blue filters) over its sensor. Using a narrowband filter, like H-alpha which is deep red, would only allow light to pass through the red pixels, wasting the signal from the green and blue pixels and resulting in a very inefficient, low-resolution image.

    How will the ZWO 7nm filters perform on the Orion Nebula (M42) from my backyard?

    The ZWO 7nm filters will perform exceptionally well. M42 is extremely bright in both H-alpha and OIII. From a light-polluted backyard, these filters will darken the sky background significantly, allowing you to use longer exposures to capture the faint outer structures of the nebula without washing out the core. You will be able to resolve the intricate details within the Trapezium region with far more contrast than with standard LRGB filters.

    What are the best deep-sky objects for this ZWO narrowband filter set?

    This set is ideal for emission nebulae, which are clouds of ionized gas. Excellent targets include:

    • North America Nebula (NGC 7000): Rich in H-alpha and SII.
    • Veil Nebula Complex (NGC 6960/6992): A supernova remnant that glows brightly in H-alpha and OIII.
    • Eagle Nebula (M16): Famous for the "Pillars of Creation," which are stunning in the Hubble Palette.
    • Heart and Soul Nebulae (IC 1805 & IC 1848): Large complexes that are perfect for wider-field scopes.

    Galaxies and reflection nebulae are not good targets for these filters as they emit broadband light.

    Do I need a filter wheel to use the ZWO 1.25" filter set?

    A filter wheel is the most convenient way to automate switching between the H-a, OIII, and SII filters during an imaging session. However, it is not strictly necessary. You can also use a manual filter drawer or a filter slider, which allows you to swap the 1.25" threaded filters by hand between exposures.

    What is the "Hubble Palette" and how do I create it with these ZWO filters?

    The Hubble Palette, also known as "SHO," is a color mapping technique used to visualize the different gases in a nebula. After capturing separate images with each of the ZWO filters, you combine them in post-processing software like PixInsight or Photoshop. The standard mapping is:

    • S-II Data → Red Channel
    • H-a Data → Green Channel
    • O-III Data → Blue Channel

    This creates the iconic gold-and-teal aesthetic seen in many images from the Hubble Space Telescope.

    Why would I choose this ZWO 7nm set over a more expensive 3nm set?

    While 3nm filters offer the highest possible contrast, the 7nm set is often a better choice for practicality. The ZWO 7nm filters allow more light through, which means shorter exposure times are needed to get a good signal. This is a major benefit if you have tracking limitations or less-than-perfect seeing conditions. They are also more affordable, providing an excellent entry into serious narrowband imaging.

  • SKU ZWO-NB7NMD1.25
    Product Type Filter Set
    Filter Class Narrowband
    Size 31.75mm (1.25")
    Shape Round
    Mounting Style Threaded Cell
    Bandwidth 7 nm

    • 1.25" Mounted H-a 7nm Filter

      × 1

    • 1.25" Mounted OIII 7nm Filter

      × 1

    • 1.25" Mounted SII 7nm Filter

      × 1

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