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ZWO 2.5mm 170° All-Sky Lens - For 1/2" Sensors

ZWO 2.5mm 170° All-Sky Lens - For 1/2" Sensors

by ZWO
SKU ZWO-LENS-2-5
$22.00 - $22.00
$22.00
$22.00 - $22.00
$22.00
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  • Focal Length: 2.5mm
  • Field of View: 170° Diagonal
  • Aperture: f/1.2
  • Mount: CS-Mount Standard
  • Format: 1/3" Sensor Coverage
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Capture the Entire Sky — The ZWO 2.5mm 170° CS-Mount Lens

    The ZWO 2.5mm 170° lens is designed to solve a specific problem for planetary and guide camera owners: how to transform a narrow-field sensor into an all-sky monitoring tool. This compact lens attaches directly to ZWO's smaller-format cameras, converting them into powerful instruments for meteor detection, cloud monitoring, or capturing the entire sweep of the Milky Way in a single frame.

    The 170° All-Sky Perspective

    The core of this lens is its super-wide-angle optical design, delivering a massive 170° diagonal field of view on a 1/3" sensor. This extreme perspective is the key to its function, allowing you to see from horizon to horizon. For the practical astronomer, this means you can run a dedicated meteor camera overnight or check sky conditions at your remote observatory without needing a complex fisheye setup.

    This wide field makes it possible to capture entire constellations and the movement of celestial objects over hours. It's an ideal tool for creating dramatic time-lapses of the night sky's rotation or monitoring for transient events like bolides and iridium flares that would be missed by any conventional telescope.

    Direct-Fit CS-Mount Interface

    Engineered with a standard CS-mount thread, this lens attaches directly and securely to the CS-mount adapter supplied with ZWO cameras like the ASI178MC.

    The trade-off for this simplicity is its dedicated compatibility. This lens is specifically designed for the smaller 1/3" and 1/2" class sensors and will not illuminate the larger sensors found in ZWO's cooled deep-sky cameras. It is a specialist tool built for a specific range of cameras.

    Manual Focus for Full Control

    The separate focus ring allows you to dial in sharp stars, a critical capability that many basic security lenses lack. This ensures your all-sky images are not just wide, but also crisp. Achieving perfect focus at 170° can be sensitive, so small, iterative adjustments are key to getting the best performance across the frame.

    Your Personal Sky Monitor

    Paired with a camera like the ASI178MC and software like AllSkEye or FireCapture, this lens creates a fully autonomous sky monitoring station. Imagine setting up your system before sunset and waking up to a complete record of the night's activity. You can review frames for passing meteors during a shower, monitor for incoming clouds that could ruin an imaging session, or simply enjoy a full-dome view of your local sky.

    On a night with passing clouds and the Milky Way overhead, a time-lapse will show the galactic core moving steadily across the sky while weather systems drift by. This contextual view is invaluable for remote imagers and provides a unique perspective on the dynamic nature of the night sky that is impossible to achieve with a telescope alone.

  • Which ZWO cameras work with the 2.5mm lens?

    This lens is designed for ZWO cameras with a CS-mount and a 1/3" or 1/2" sensor. It is an ideal match for cameras like the ASI178MC for all-sky applications.

    Can I use this lens on a ZWO cooled camera like the ASI533MC Pro?

    No, this lens is not recommended for cameras with larger sensors like the ASI533MC Pro. The lens's image circle is too small and will cause severe vignetting, illuminating only a small portion of the sensor.

    Is this lens good for deep-sky astrophotography?

    While it can capture wide star fields, this lens is not designed for detailed deep-sky imaging. Its purpose is extremely wide-field monitoring, not resolving fine detail in nebulae or galaxies. For those targets, a dedicated camera lens adapter and photographic lens are better choices.

    How do I focus the 2.5mm lens?

    The lens has a manual focus ring. For astronomical use, point the camera at a bright star, and using your capture software's live view, make small adjustments to the focus ring until the star appears as a sharp, tight point of light.

  • Focal Length 2.5mm
    Aperture f/1.2
    Diagonal Field of View 170°
    Mount Type CS-Mount
    Sensor Format 1/3"
    Weight 45g (1.6 oz)
    Dimensions ø28mm x 18.5mm
    • ZWO 2.5mm 170° CS-Mount Lens

      ZWO 2.5mm 170° Lens

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  • ZWO 2-Year Warranty