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July 1st: Store will be closed for Canada Day. Orders placed that day will ship on July 2nd.
July 1st: Store will be closed for Canada Day. Orders placed that day will ship on July 2nd.
ZWO Electronic Filter Wheel EFW Gen2 - 5 x 1.25"
ZWO Electronic Filter Wheel EFW Gen2 - 5 x 1.25"
ZWO Electronic Filter Wheel EFW Gen2 - 5 x 1.25"

ZWO Electronic Filter Wheel EFW Gen2 - 5 x 1.25"

by ZWO
SKU ZWO-EFW-5x1.25-25
CA$279.00 - CA$279.00
CA$279.00
CA$279.00 - CA$279.00
CA$279.00
Price Match Policy!
  • 5 filter positions for 1.25" or 31mm filters
  • Adds 20 mm of back focus to the imaging train
  • USB-C powered and controlled
  • Redesigned housing for improved light leak prevention
  • Compatible with ASIAIR and ASCOM drivers
1 in stock
Qualifies for FREE Shipping in Canada on orders over $500.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO EFW 5-Position Filter Wheel for 1.25" and 31 mm Filters (2025)

    The ZWO EFW 5-Position Filter Wheel automates your imaging sequences by holding a full LRGB or narrowband filter set, accepting both 1.25" and 31mm formats across its 5 positions. This second-generation wheel is powered entirely via USB and consumes only 20 mm of back focus, making it a compact addition to nearly any imaging train.

    Automated Imaging with 5 Filter Positions

    This wheel holds up to 5 different filters, allowing you to load a complete LRGB (Luminance, Red, Green, Blue) or SHO (Sulphur-II, Hydrogen-alpha, Oxygen-III) set for monochrome imaging. The internal stepper motor rotates the carousel with high precision, ensuring each filter centers perfectly in the light path every time. Once installed, you can control filter changes remotely via ASIAIR or ASCOM, eliminating the need to manually disturb the telescope for filter swaps during an imaging session.

    20mm Back Focus with Redesigned Housing

    The Gen2 design adds exactly 20 mm to your optical train, a critical measurement for planning correct spacing with reducers and flatteners. ZWO has redesigned the housing with an improved slot-style closure and a sealed motor compartment to eliminate stray light that could otherwise compromise long exposures. The move to a modern USB-C port provides a more reliable connection for both power and data and is easier to plug in while working in the dark.

    Flexible Integration with M42 and 1.25" Adapters

    The filter wheel is designed for maximum compatibility with common astronomy equipment. It features female M42x0.75 (T2) threads on both the telescope and camera sides for a secure, threaded connection. For added flexibility, the package includes a 1.25" nosepiece to connect to a standard focuser and a 1.25" eyepiece holder for the camera side, allowing you to build your imaging train using multiple connection standards.

  • What types of filters fit in the ZWO EFW 5-Position Filter Wheel?

    This filter wheel accepts two standard sizes. You can install up to 5 standard 1.25" mounted filters with male threads, or up to 5 31mm unmounted filters. This covers the most common filter formats for small-to-medium format astronomy cameras.

    How much back focus does the ZWO EFW Gen2 add to an imaging train?

    The filter wheel body itself consumes precisely 20 mm of back focus. This is the distance from the front flange to the rear flange of the main housing. You must account for this distance when calculating the spacing for your field flattener or reducer.

    Is the ZWO EFW 5-Position Filter Wheel compatible with the ASIAIR Plus?

    Yes. The ZWO EFW is fully compatible with all ASIAIR models. You can connect it via its USB-C port directly to the ASIAIR, where it will be automatically recognized. This allows you to select filters and build automated imaging plans directly within the ASIAIR app.

    Do I need an external power supply for the ZWO EFW Gen2?

    No. The filter wheel is powered entirely through its USB connection. A single USB-C cable connected to your control computer, ASIAIR, or a powered USB hub provides both power and data for the unit, simplifying cable management at the telescope.

    Can I use this EFW for imaging the Orion Nebula (M42) with a monochrome camera?

    Absolutely. For a target like the Orion Nebula (M42), you could load the ZWO EFW with Luminance, Red, Green, and Blue filters for a full-color LRGB image. Alternatively, for a narrowband image from light-polluted skies, you could load H-alpha, O-III, and S-II filters to capture the distinct ionized gases within the nebula.

    Will the ZWO EFW 5-Position wheel cause vignetting with an APS-C sensor camera?

    While designed for smaller sensors, 1.25" and 31mm filters can often be used with APS-C sensors without significant vignetting, especially on slower telescopes (f/7 or higher). On faster systems (f/5 or lower), you may see some darkening in the corners of your images. For full-frame sensors or very fast optics, a larger filter wheel using 2" or 36mm filters is recommended.

  • SKU ZWO-EFW-5X125-25
    Product Type Electronic Filter Wheel
    Filter Positions 5
    Supported Filter Sizes 1.25" or 31mm
    Back Focus Consumption 20 mm
    Power Source USB
    Mounting Style Accepts Both Threaded or Drop-In
    Warranty 2 Years

    • EFW 5-Position Filter Wheel (2025)

      × 1

    • M42M to M42M (T2) Adapter

      × 1

    • 1.25" Nosepiece

      × 1

    • 1.25" Connection Adapter

      × 1

    • M2.5x6 Screws

      × 6

    • M2x4 Screws

      × 26

    • M4x12 Screws

      × 2

    • Filter Masks

      × 10

    • 2 M USB-C Cable

      × 1

    • 0.5 M USB-C Cable

      × 1

    • Philips Head Screwdriver

      × 1

    • 1.25" Cover & Cap

      × 1

  • ZWO 2-Year Limited Warranty