ZWO EFW 8x1.25" (31mm) Electronic Filter Wheel

Description

ZWO EFW 8x1.25"/31mm Electronic Filter Wheel

The ZWO EFW 8x1.25"/31mm Electronic Filter Wheel is designed to give astrophotographers smooth, precise, and reliable filter control in a compact and lightweight package. Weighing only 400 g, this latest version is slightly larger than previous models yet still slim and portable, with a body thickness of just 20 mm.

CNC-milled from aircraft-grade aluminum, the filter wheel offers both strength and durability without unnecessary bulk. At its core is a high-quality stepper motor from NPM, Japan, ensuring long-term reliability, smooth rotation, and accurate positioning. The wheel can rotate in both clockwise and counterclockwise directions, giving you fast and flexible access to your filters during imaging sessions.

Powering the EFW is simple and efficient: it requires only one USB2.0 cable, with a maximum consumption of about 120 mAh @ 5V, and can even be powered directly from a cooled ZWO camera’s USB hub—no extra cables or power supplies are needed.

When paired with the ASI1600 camera, the distance between the filter and sensor is around 10 mm. This optimized design minimizes vignetting:

• 1.25" threaded filters show no vignetting with telescopes as fast as f/5.
• 31 mm unmounted filters are suitable for optical systems as fast as f/2.

For best performance, ZWO’s new RGBL filters are recommended, providing nearly 1:1:1 RGB color balance with the ASI1600MM Pro camera.

What’s in the box?

• EFW 8x31mm filter wheel body
• 1.25" cover
• T2 nosepiece
• 1.25" holder (with cover and 2 screws)
• T2-T2 male adapter
• Filter masks
• USB2.0 cable (2 m)
• Phillips screwdriver
• Pack of M2 screws

Filter installation

• 1.25" threaded filters must be shorter than 3 mm (thread length) and less than 7 mm in height (without threads).
• 31 mm filters are secured using the included M2 screws and washers.

Installation is simple: remove the back cover, lay the wheel flat, mount the filters, secure them with screws/washers if needed, and reattach the cover.

Easy to use

Just connect the EFW via USB2.0 and install the ASCOM driver. The software will recognize the wheel as “ZWO Filter Wheel (1)” or “ZWO Filter Wheel (2),” making it possible to operate two filter wheels simultaneously if needed.