Description

ZWO EFW-51.25″ (EFW-5×1.25-25)

Electronic Filter Wheel 5-Position 1.25″/31mm Filters USB-C

The ZWO EFW-51.25″ brings the latest refinements of ZWOs next-generation filter wheel design to imagers running compact filter sets. Built around a newly optimized light-sealing structure and a CNC-machined aluminum body, this wheel delivers smooth, repeatable rotation with greatly improved resistance to stray light. For LRGB imagers or narrowband shooters who prefer a minimal, efficient filter loadout, the five-position carousel keeps your system lightweight, rigid, and ready for fully automated imaging.

Refined Engineering for Cleaner, More Reliable Imaging

ZWOs updated EFW-25 series introduces several mechanical improvements over earlier wheels.
A redesigned slot-fit chassis tightens the interface between the top and bottom plates, while new dual light-blocking pads at the lateral connection points create an additional barrier against stray illumination. The motor compartment is now fully enclosed, preventing light intrusion and adding environmental protection during long-duration imaging.

These upgrades work quietly in the background, helping preserve uniform flats and consistent background levels across every filter position.

Compact 5-Position Carousel for 1.25″/31mm Filters

The internal filter disk holds five 1.25″ mounted filters or five 31mm unmounted filters, making this wheel an ideal match for small-sensor mono cameras or lightweight portable rigs. The carousel itself is machined from 6061 aluminum alloy, maintaining rigidity without unnecessary mass.

At roughly 20mm thick, the slim housing integrates easily into ZWO imaging trains, reducing spacing complications and keeping your system balanced.

Power, Connectivity & Software Control

A single USB-C port handles both control and power, drawing only 120 mA at 5V no external power source required.
The wheel is fully supported by:

• ASIAIR

• ASIStudio

• ASCOM

• ZWO SDK

The high-precision stepper motor provides accurate bidirectional indexing, enabling fully automated filter changes during unattended imaging sessions.

Compatibility

The EFW-51.25″ is fully compatible with all ZWO 1.25″ mounted filters and 31mm unmounted filters, including LRGB, SHO, and multi-band options. It bolts directly to ZWO cameras and accessories using the included adapters, preserving rigid alignment for long-exposure work.

Whats in the Box

• EFW Body

• 1.25″ Cover

• 1.25″ Holder

• M42MM42M Adapter

• 1.25″ Nosepiece

• M2.56 Screws (6 pcs)

• M24 Screws (26 pcs)

• M412 Screws (2 pcs)

• 375 mm Phillips Screwdriver

• 1.25″ Bracket

• USB 2.0 Cable (2 m)

• USB 2.0 Cable (0.5 m)

• Bag of Filter Masks (10 pcs)

Imaging Tip

If you shoot with fast refractors or short-backfocus systems, consider installing your filters so the orientation matches the direction of rotation. This helps maintain optimal spacing between the filter surface and the front of your cameras protective window, improving edge illumination uniformity when using 31mm filters at faster focal ratios.