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July 1st: Store will be closed for Canada Day. Orders placed that day will ship on July 2nd.
ZWO CH4 Methane Filter - 20nm 1.25"

ZWO CH4 Methane Filter - 20nm 1.25"

by ZWO
SKU ZWO-CH4
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
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  • Reveals high-altitude detail on Jupiter and Saturn
  • 20nm bandpass centered on the methane absorption line
  • Standard 1.25" (31.75mm) threaded cell
  • Reduces effects of atmospheric seeing
  • 2-Year ZWO Warranty
1 in stock
Qualifies for FREE Shipping in Canada on orders over $500.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO 20nm CH4 Methane Band Filter - 1.25"

    The ZWO CH4 Methane Filter isolates a specific 20nm bandpass deep in the near-infrared spectrum, targeting the strong methane absorption lines in the atmospheres of gas giants. Housed in a standard 1.25" (31.75mm) threaded cell, this filter is purpose-built to reveal high-altitude clouds and storm systems on Jupiter and Saturn that are completely invisible in visible light.

    Isolating Planetary Detail with a 20nm Bandpass

    The 20nm FWHM (Full Width at Half Maximum) is precisely tuned to the methane (CH4) absorption band. When you image Jupiter, regions rich in methane absorb this wavelength of light and appear dark, while high-altitude features like the Great Red Spot or bright equatorial zones reflect this light strongly, creating dramatic contrast. This allows you to resolve atmospheric stratification and storm structures that are otherwise lost against the planet's brighter, lower-level cloud decks.

    Seeing-Resistant Imaging with a 1.25" Filter

    Because this filter operates in the near-infrared, it leverages a key principle of atmospheric optics: longer wavelengths of light are less susceptible to distortion from air turbulence ("seeing"). On nights of average or poor seeing, the ZWO CH4 filter can deliver a steadier, sharper image than a standard luminance or color filter. This stability is critical for capturing fine planetary detail, making this 1.25" filter an essential tool for dedicated planetary imagers.

    Compatibility and Use with Monochrome Cameras

    This is a specialized filter designed for monochrome cameras that have good sensitivity in the near-infrared. While it can be used with some IR-sensitive color cameras, the best results are achieved with a mono sensor where you can optimize exposure for this specific wavelength. The standard 1.25" threaded cell ensures it fits any standard filter wheel, filter drawer, or 1.25" nosepiece, making it a seamless addition to your existing imaging train.

    • Standard Threads: The 1.25" cell is threaded to screw directly into standard astronomical accessories.
    • Mono Sensor Optimized: Achieves maximum contrast and detail when paired with a sensitive monochrome planetary camera.
    • Protective Case: Includes a durable plastic case to keep the filter safe and clean when not in use.

  • How will the ZWO CH4 filter change my images of Jupiter's Great Red Spot?

    The Great Red Spot (GRS) is a high-altitude storm. With the ZWO CH4 filter, the GRS will appear exceptionally bright against the surrounding, darker methane-rich atmospheric belts. This dramatically increases its contrast and visibility, allowing you to capture its structure even when it appears washed out in visible-light images.

    What camera do I need to use the ZWO 20nm CH4 filter with my telescope?

    You need an imaging camera with good sensitivity in the near-infrared (around 890nm, where methane absorbs). Monochrome planetary cameras are the ideal choice as they typically have higher IR sensitivity than one-shot color cameras. Standard DSLRs are generally not sensitive enough at this wavelength without modification.

    Can I use the ZWO CH4 filter for visual observing?

    No, this filter is designed for imaging only. The human eye is not sensitive to the near-infrared wavelengths that the ZWO CH4 filter transmits, so you would not be able to see anything through it visually.

    How does the ZWO CH4 filter help with bad seeing conditions?

    The filter passes light in the near-infrared part of the spectrum. These longer wavelengths are less distorted by turbulence in Earth's atmosphere ("seeing") compared to shorter, visible-light wavelengths. The result is a more stable image at the sensor, which often translates to sharper final images on nights with unsteady air.

    Will this 1.25" ZWO CH4 filter fit my existing filter wheel?

    Yes. The ZWO CH4 filter is housed in a standard 1.25" (31.75mm) threaded cell. It will screw into any filter wheel, filter drawer, or accessory designed to accept standard 1.25" astronomical filters.

    Is the ZWO CH4 filter useful for planets other than Jupiter and Saturn?

    While it is most effective on Jupiter and Saturn due to their prominent methane atmospheres, it can also be used to study the atmospheres of Uranus and Neptune. However, these ice giants are much dimmer and smaller, requiring larger telescopes and longer exposures to achieve good results.

  • SKU ZWO-CH4
    Filter Type CH4 (Methane) Band
    Bandpass (FWHM) 20nm
    Size 31.75mm (1.25")
    Format Threaded Round Cell
    Intended Use Planetary Imaging
    Warranty 2 Years

    • ZWO CH4 20nm Methane Filter in 1.25" Cell

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    • Plastic Filter Case

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  • ZWO 2-Year Limited Warranty