ZWO EFW-8×1.25" Electronic Filter Wheel | 8-Position USB-C Wheel for 1.25"/31mm Filters

Electronic Filter Wheel · 8 Positions · 1.25"/31mm Filters · USB-C

For imagers who want a complete LRGB and narrowband workflow always ready to go, the ZWO EFW-8×1.25" provides eight filter positions in the newly refined EFW-25 body. This next-generation filter wheel brings upgraded light-leak protection, improved mechanical sealing, and quiet, precise stepper-motor rotation—all in a slim, CNC-machined aluminum housing designed to integrate seamlessly with ZWO cameras and imaging systems.

Whether you run full SHO plus LRGB, or you simply appreciate having extra slots available for specialty filters, this versatile 8-position wheel keeps your imaging train flexible, automated, and ready for long-form deep-sky sessions.

Improved Structural Design for Better Light Control

The EFW-25 series introduces ZWO’s updated approach to stray-light suppression.
The housing uses a newly engineered slot-fit chassis that tightens the interface between the front and back plates, reducing internal light paths that can affect flats and background uniformity. Dual light-blocking pads at the wheel’s lateral connection points provide additional shielding, while the stepper-motor compartment is now fully enclosed for superior internal isolation.

The result is cleaner, more consistent imaging performance—especially important when shooting broadband and narrowband data across many hours of integration time.

Eight Filter Positions for Maximum Flexibility

The 8-position carousel accepts:

• Eight 1.25" mounted filters

• Eight 31mm unmounted filters

This layout allows a complete LRGB + SHO + extra slot configuration without swapping carousels or opening the wheel during an imaging run.
The disk itself is machined from strong, lightweight 6061 aluminum alloy, maintaining rigidity and balance without unnecessary mass.

Body thickness remains a compact ~20mm, preserving backfocus and simplifying spacing with common ZWO cameras, OAGs, and reducers.

Power, Connectivity & Software Integration

A single USB-C port handles both power and control. No external 12V supply is needed—the wheel draws only ~120 mA at 5V.

Compatible software includes:

• ASIAIR

• ASIStudio

• ASCOM drivers

• ZWO SDK-based control software

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

Compatibility

The EFW-8×1.25" is fully compatible with all ZWO filters in the 1.25" mounted and 31mm unmounted families.
Its M42-based connections and included accessories make it easy to pair with ZWO cooled and uncooled cameras, as well as common imaging trains that rely on the threaded T-system.

What’s in the Box

(Same accessory set as the 5×1.25" edition unless ZWO revises packaging—this list reflects current published contents.)

• EFW Body

• 1.25" Cover

• 1.25" Holder

• M42M–M42M Adapter

• 1.25" Nosepiece

• M2.5×6 Screws (6 pcs)

• M2×4 Screws (26 pcs)

• M4×12 Screws (2 pcs)

• 3×75 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

When using 31mm unmounted filters, be sure each filter is centered within its mask before tightening the retainer screws. Proper alignment helps maintain even edge illumination—especially critical when working with fast refractors or wide APS-C sensors. Taking a moment to seat each filter correctly can noticeably improve the uniformity of your flats.