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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.
ZWO EFW - 7 x 36mm
ZWO EFW - 7 x 36mm

ZWO EFW - 7 x 36mm

by ZWO
SKU ZWO-EFW-7x36-II
Save 20% Save 20%
$299.00
$299.00 - $299.00
$299.00
$239.00
$239.00 - $239.00
$239.00
Price Match Policy!
  • Holds seven 36mm unmounted filters
  • Adds only 20mm of back focus to the imaging train
  • Powered and controlled via a single USB-C cable
  • Weighs 515g for minimal impact on mount balance
  • Compatible with filter thicknesses from 1.9mm to 3.5mm
2 in stock
Qualifies for FREE Shipping in CONUS on orders over $350.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO EFW - 7 x 36mm Electronic Filter Wheel

    The ZWO EFW for 7 x 36mm filters automates your imaging sequence with a robust, lightweight design that adds only 20mm of back focus to your optical train. Its 7-position carousel accepts unmounted 36mm filters from 1.9mm to 3.5mm thick, accommodating a full LRGB and SHO narrowband pallet in a single unit. The entire 515g assembly is powered and controlled via a single USB-C cable, drawing a minimal 120mAh at 5V to keep your setup clean and reliable.

    Automated 7-Filter Sequencing in a 20mm Profile

    This filter wheel is engineered for efficiency in complex imaging projects. The 7-position capacity allows you to house both broadband (LRGB) and narrowband (SHO) filters simultaneously, eliminating the need for manual swaps during an imaging session. At only 20mm thick, it preserves critical back focus, enabling use with a wide range of reducers, flatteners, and off-axis guiders without compromising optical performance.

    Precision Control and Reliable Mechanics

    At the core of the EFW is a high-precision Japanese NPM stepper motor, ensuring quiet, repeatable filter selection with bidirectional rotation for the shortest path. The body is CNC-machined from a single block of aircraft-grade aluminum for rigidity and light weight. This robust construction prevents flexure and maintains optical alignment as the carousel rotates, ensuring your calibration frames remain consistent throughout the night.

    • Single-Cable Operation: A single USB-C port handles both power and data, drawing a low 120mAh at 5V. This allows it to be powered directly from a ZWO cooled camera's USB hub, reducing cable clutter.
    • Direct Camera & OAG Integration: The housing features direct-connect bolt patterns for seamless integration with ZWO cameras and the M68 Off-Axis Guider, creating a solid, flex-free imaging train.
    • Redesigned Light Seal: This latest version features an improved chassis seal and an enclosed motor compartment, preventing stray light from contaminating long exposures and critical calibration frames.

    ZWO 7x36mm EFW vs. 8x1.25"/31mm EFW

    While both filter wheels offer automated control, the choice depends entirely on your camera sensor and telescope's corrected image circle. The 36mm format is the superior choice for modern APS-C sensors, while the 1.25"/31mm EFW is better suited for smaller sensors.

    • Competitor Advantage (8x1.25"/31mm EFW): Offers one additional filter slot and is compatible with the vast, affordable selection of 1.25" mounted filters. It is also typically lighter and more compact.
    • This Product's Advantage (7x36mm EFW): The unmounted 36mm filters provide a larger clear aperture, completely preventing vignetting on popular APS-C sensors like the IMX571 used in the ASI2600. The 1.25" format will often clip the corners of the field with these larger sensors, especially on faster optical systems.

  • What is the main advantage of the ZWO EFW 7x36mm for an APS-C camera?

    The primary advantage is preventing vignetting. The 36mm clear aperture of the unmounted filters is large enough to fully illuminate APS-C sensors (like the Sony IMX571) without the corner-darkening that often occurs when using smaller 1.25" or 31mm filters, especially in faster f-ratio telescopes.

    Can I use filters from other brands in the ZWO EFW 7x36mm?

    Yes, you can use 36mm unmounted filters from any manufacturer, provided their thickness is between 1.9mm and 3.5mm. Filters outside this range may not seat correctly or could interfere with the wheel's rotation.

    How is the ZWO EFW 7x36mm powered and controlled?

    The filter wheel is powered and controlled through a single USB-C cable. It draws a very low 120mAh at 5V, which allows it to be powered directly from the USB hub on a ZWO cooled camera, minimizing cable drag and complexity.

    How do I achieve the standard 55mm back focus with the ZWO EFW 7x36mm?

    ZWO provides various adapters to achieve 55mm back focus with their cameras. Typically, this involves connecting the EFW (which consumes 20mm) directly to the camera (e.g., ASI2600 with its 17.5mm native back focus) and then using the appropriate combination of included M54/M48 adapters and spacers to reach the required distance from your flattener or reducer.

    Will the ZWO EFW 7x36mm work for imaging the Orion Nebula (M42) with an 8-inch f/4 Newtonian?

    Absolutely. For an f/4 system with an APS-C camera, the 36mm filters are essential to avoid vignetting on a large, bright target like the Orion Nebula (M42). The 7-slot capacity lets you load LRGB filters for the core and SHO filters to capture the faint, expansive hydrogen-alpha structures in the surrounding molecular cloud, all in one automated session.

    What is the purpose of the included filter masks for the ZWO EFW 7x36mm?

    The included filter masks are designed to block stray light that might reflect off the edges of the filter glass itself. They are placed over the filters during installation to further reduce internal reflections and improve the contrast of your final images, which is especially important for long narrowband exposures.

  • Filter Wheel Type Electronic Filter Wheel
    Filter Capacity 7 Positions
    Supported Filter Size 36mm Unmounted
    Supported Filter Thickness 1.9mm - 3.5mm
    Back Focus Consumption 20mm
    Power Input USB-C
    Power Consumption 120mAh @ 5V
    Weight 515g
    Body Construction CNC-milled aircraft-grade aluminum
    Motor Japanese NPM stepper motor

    • ZWO EFW 7x36mm Body

      × 1

    • M54M-M48F Adapter

      × 1

    • M54M-M42F Adapter

      × 1

    • M48 to M54 Step-Up Ring

      × 1

    • USB 2.0 Cable (2m)

      × 1

    • USB 2.0 Cable (0.5m)

      × 1

    • Filter Masks

      × 10

    • M2.5x6 Screws

      × 6

    • M2x4 Screws

      × 26

    • Phillips Head Screwdriver

      × 1

  • ZWO 2-Year Warranty