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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
ZWO EAFN Electronic Automatic Focuser
ZWO EAFN Electronic Automatic Focuser

ZWO EAFN Electronic Automatic Focuser

by ZWO
SKU ZWO-EAFN
$199.00 - $199.00
$199.00
$199.00 - $199.00
$199.00
Price Match Policy!
  • Handles imaging payloads up to 11 lbs (5kg)
  • High-precision stepper motor with 128:1 gear ratio
  • Single USB-C port for power and data
  • ASCOM, INDI, and ASIAIR compatible
  • All-metal, red anodized housing weighing 0.47 lbs
48 in stock
Qualifies for FREE Shipping in CONUS on orders over $350.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO Electronic Automatic Focuser (EAFN)

    The ZWO EAFN Electronic Automatic Focuser supports imaging trains up to 11 lbs with a high-precision stepper motor featuring a 128:1 reduction ratio. This entire system is powered and controlled via a single USB-C connection and is housed in a compact, all-metal body that weighs only 0.47 lbs (215g).

    Automated Focusing with an 11 lb Capacity

    The EAFN's stepper motor and gearbox confidently drive imaging loads up to 11 lbs (5kg), eliminating focus shift even with heavy components like cooled cameras, filter wheels, and off-axis guiders. This robust capacity ensures that autofocus routines run reliably without mechanical slippage, maintaining critical focus on demanding optical systems like Schmidt-Cassegrains and large refractors.

    Stepper Motor Precision with a 128:1 Ratio

    At the core of the EAFN is a stepper motor with a 7.5° step angle, geared down through a 128:1 reducer. This results in incredibly fine, repeatable focus adjustments of approximately 2.8 microns per step, allowing software to dial in perfect focus that is far more precise than humanly possible with a manual knob. While the EAFN can execute these adjustments automatically in response to filter changes or meridian flips, achieving focus correction based on temperature shifts requires the optional ZWO Temperature Sensor for real-time thermal data.

    • Precise Adjustments: The high-resolution motor allows autofocus software to achieve a significantly sharper V-curve, resulting in tighter stars across the entire frame.
    • Repeatability: Return to a precise focus point for different filters or after temperature changes with absolute accuracy, night after night.
    • Integrated Control: The EAFN connects directly to the ASIAIR ecosystem or ASCOM/INDI-compatible software, integrating seamlessly into established imaging workflows.

    ZWO EAFN vs. Original ZWO EAF

    The EAFN is a direct evolution of the original, widely-adopted ZWO EAF, incorporating key hardware upgrades for modern astrophotography rigs. The primary advantages of the newer EAFN are the higher-torque motor and the streamlined connectivity.

    • Payload Capacity: The original EAF was also rated for 11 lbs (5kg). The EAFN uses a higher-torque motor, which requires more input power than earlier ASIAIR USB ports supply.
    • Power and Data: The EAFN uses a single, modern USB-C port for both 5V power and data. The original EAF required a separate 12V DC barrel connector for power and a legacy USB 2.0 Type-B port for data, complicating cable management.
    • Form Factor: While sharing a similar mounting pattern for broad compatibility, the EAFN features a refined, slightly more compact housing.

  • How does the 11 lb capacity of the ZWO EAFN benefit imaging with an SCT?

    Schmidt-Cassegrain telescopes often require moving a heavy primary mirror for focusing. The ZWO EAFN's 11 lb (5kg) payload capacity provides ample torque to move the mirror assembly smoothly and without motor strain, even with a heavy camera, filter wheel, and focal reducer attached. This prevents mirror shift and ensures autofocus routines are consistent.

    What software do I need to use the ZWO EAFN's autofocus?

    The ZWO EAFN integrates seamlessly with ZWO's own ASIAIR devices. For PC or Mac-based control, it is fully compatible with any software that supports the ASCOM (Windows) or INDI (Mac/Linux) platforms, including popular applications like N.I.N.A., Sequence Generator Pro, and KStars/Ekos.

    Can I use the ZWO EAFN for visual observing without a computer?

    Yes. While its primary function is for automated imaging, you can control the ZWO EAFN manually without a computer by connecting the optional ZWO Hand Controller (sold separately) to its 3.5mm port.

    Will the ZWO EAFN work with my William Optics refractor during a multi-night run of the Andromeda Galaxy (M31)?

    Absolutely. The ZWO EAFN is compatible with most William Optics focusers. For a multi-night project on M31, you can program your imaging software (like N.I.N.A. or ASIAIR) to automatically re-run the autofocus routine at set intervals, after every filter change, or after a meridian flip, ensuring your focus remains sharp across multiple nights.

    Does the ZWO EAFN require a separate 12V power supply?

    No, the ZWO EAFN simplifies cable management by drawing both power and data through its single USB-C port when connected to a computer or ASIAIR. The older ZWO EAF model required a separate 12V power input in addition to its USB data cable.

    What is the main advantage of the ZWO EAFN over the older ZWO EAF model?

    The two main advantages are payload and connectivity. The ZWO EAFN supports an 11 lb payload with a higher-torque motor. It also uses a single USB-C cable for both power and data, whereas the original required two separate cables (USB-B and a 12V DC barrel jack).

  • SKU ZWO-EAFN
    Focuser Type Electronic Stepper Motor
    Payload Capacity 11 lbs (5 kg)
    Motor Stepper Motor
    Step Angle 7.5°
    Reduction Ratio 128:1
    Resolution per Step Approx. 2.812 μm
    Power / Data Interface USB-C
    Supply Voltage 5V @ 500mA (via USB-C)
    Dimensions 41 mm x 52 mm x 70.3 mm
    Weight 0.47 lbs (215 g)

    • ZWO Electronic Automatic Focuser

      × 1

    • Standard Bracket

      × 1

    • 2m USB 2.0 Type-C to Type-A Cable

      × 1

    • Flexible Couplings (4-4mm, 4-5mm, 4-6mm, 4-7mm)

      × 4

    • M5 x 10 Hex Screws

      × 2

    • M4 x 8 Hex Screws

      × 4

    • Spacers (5mm Inner Diameter)

      × 5

    • 3mm Hex Wrench

      × 1

    • 2mm Hex Wrench

      × 1

    • Quick Guide

      × 1

  • ZWO 2-Year Limited Warranty