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July 1st: Store will be closed for Canada Day. Orders placed that day will ship on July 2nd.
ZWO EFW - 7 x 50mm Square Filter Wheel

ZWO EFW - 7 x 50mm Square Filter Wheel

by ZWO
SKU ZWO EFW-7x50
CA$849.00 - CA$849.00
CA$849.00
CA$849.00 - CA$849.00
CA$849.00
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  • Holds seven 50mm square unmounted filters
  • Designed for large-format sensors like the ZWO ASI461MM Pro
  • Direct bolt-on connection for maximum rigidity
  • Powered and controlled via a single USB 2.0 cable
  • ASCOM and ASIAIR compatible
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO 7 Position Electronic Filter Wheel for 50mm Square Filters

    The ZWO EFW-7X50 holds 7 different 50mm square filters for automated imaging, a format required to prevent vignetting on large medium-format sensors. Its design uses 12 M2.5x6 screws for direct attachment and draws power from a 2m USB 2.0 cable, creating a rigid and reliable imaging train.

    7 Positions for 50mm Square Filters

    This wheel's 7-filter capacity lets you load an entire LRGB and narrowband (SHO) filter set at once, enabling fully automated imaging sequences without manual changes. The 50mm square format is specifically chosen to ensure the light cone fully illuminates large sensors, such as the medium-format chip in the ASI461MM Pro, from corner to corner.

    Direct-Bolt Integration Using 12 M2.5x6 Screws

    Unlike universal filter wheels that rely on threaded connections, the ZWO EFW-7X50 bolts directly to the ZWO ASI461MM Pro camera body and M68 OAG. This connection, secured by the included 12 M2.5x6 screws, forms a single, rigid unit that eliminates the potential for tilt or flexure common in heavy, threaded imaging trains. This design choice prioritizes stability over universal compatibility.

    Reliable Filter Changes via USB 2.0

    A high-quality NPM stepper motor ensures precise, repeatable filter positioning with bidirectional movement for the shortest path. The entire unit is powered and controlled through a single USB 2.0 connection, minimizing cable clutter. ZWO includes both a 2m and a 0.5m cable to accommodate different setups, and the wheel is fully supported by ASIAIR and ASCOM platforms for seamless integration with your acquisition software.

    Eliminating Vignetting: 50mm Square vs. M48 Threaded Filters

    For imagers using medium-format sensors, standard 2-inch filters with M48 threads become the bottleneck in the optical path. Their sub-48mm clear aperture physically blocks light from reaching the corners of a large sensor, causing significant vignetting and data loss. The ZWO EFW-7X50 solves this by using unmounted 50mm square filters, which offer a clear aperture wide enough to deliver an evenly illuminated field across the entire sensor, preserving both signal and star shape to the edge of the frame.

  • Why do I need the ZWO EFW-7X50 for a camera like the ASI461MM Pro?

    A medium-format sensor like the one in the ASI461MM Pro is physically larger than the clear aperture of a standard 2-inch threaded filter. Using smaller filters will cause vignetting, where the corners of your images are dark. The ZWO EFW-7X50 uses 50mm square filters to ensure the entire sensor is illuminated, preventing data loss.

    Can I use standard 2-inch round threaded filters in the ZWO EFW-7X50?

    No. This filter wheel is specifically designed for 50mm x 50mm unmounted square filters. It does not have the M48 threads required to accept standard 2-inch mounted filters.

    Does the ZWO EFW-7X50 require a separate 12V power supply?

    No, it does not. The filter wheel is powered and controlled entirely through its USB 2.0 port, using the included USB cable. This simplifies cable management at the telescope.

    How do I control the ZWO EFW-7X50 filter wheel?

    You can control the ZWO EFW-7X50 using a ZWO ASIAIR device or through a computer running any ASCOM-compatible astrophotography software, such as N.I.N.A. or Sequence Generator Pro.

    If I'm imaging the Andromeda Galaxy (M31) with the ASI461MM, will this filter wheel illuminate the entire sensor?

    Yes. The 50mm square filter format of the ZWO EFW-7X50 is designed for exactly this scenario. It provides an unvignetted field of view for large targets like the Andromeda Galaxy (M31) on large sensors, ensuring even illumination from one edge of the galaxy to the other.

    What's the process for an automated LRGB sequence on the Cygnus Loop (NGC 6960) with the ZWO EFW-7X50?

    With the ZWO EFW-7X50 loaded with L, R, G, and B filters, you can use software like the ASIAIR or ASCOM-based programs to create an automated plan. You would define the number and length of exposures for each filter, and the software will command the wheel to switch to the correct filter automatically between sets, allowing you to capture all the data for the Cygnus Loop (NGC 6960) in a single unattended session.

  • SKU ZWO-EFW-7X50
    Filter Positions 7
    Supported Filter Size 50mm Square
    Filter Type Drop-In (Unmounted)
    Power Source USB
    Product Type Electronic Filter Wheel
    Warranty 2 Years

    • 7x50mm Electronic Filter Wheel Body

      × 1

    • 2m USB 2.0 Right-Angle Cable

      × 1

    • 0.5m USB 2.0 Right-Angle Cable

      × 1

    • 2.0x75 mm Phillips Screwdriver

      × 1

    • 50x50mm Filter Masks

      × 10

    • Darkening Rings Set

      × 1

    • M2x4 Screws

      × 26

    • M2.5x6 Screws

      × 12

  • ZWO 2-Year Limited Warranty