ZWO EFW-7×2" (EFW-7x2-25)

Electronic Filter Wheel · 7 Positions · 2" Mounted or 50.4 mm Unmounted Filters · USB-C

For imagers who want the widest possible filter flexibility with large-format cameras, the ZWO EFW-7×2" delivers seven oversized filter positions in ZWO’s next-generation EFW-25 housing. Built around a fully updated anti-light-leak design, a rigid CNC-machined aluminum body, and precise stepper-motor indexing, this filter wheel is engineered for full-frame and APS-C imaging systems where clean illumination and reliable automation matter most.

If your workflow includes LRGB, SHO, and specialty filters like UV/IR or continuum, the EFW-7×2" gives you the space to keep everything loaded at once—reducing setup time and eliminating the need to swap filters between nights.

Advanced Light-Leak Protection for Better Calibration and Cleaner Subs

The EFW-25 generation focuses heavily on suppressing stray light, and the improvements are substantial:

• Refined slot-fit chassis for tighter sealing between the housing plates.

• Dual light-blocking pads on the lateral connection points to reduce internal reflections.

• Fully enclosed motor compartment to prevent light entry and improve long-term environmental resistance.

With larger filters and sensors, even a small gradient becomes obvious. These mechanical refinements help maintain your calibration integrity across long imaging sessions.

Seven Filter Positions for Large-Format Imaging

The wheel supports:

• Seven 2" mounted filters (typically ≤ ~7 mm thick)

• Seven 50.4 mm unmounted filters

This capacity allows complete LRGB + SHO + a spare slot for a specialty filter.
The carousel is machined from lightweight, rigid 6061 aluminum alloy, ensuring smooth rotation and stable seating for heavier 2" optics.

Despite holding larger filters and a bigger disk, the wheel maintains the slim ~20 mm profile that integrates easily into ZWO imaging trains.

Power, Connectivity & Software Integration

The EFW-7×2" uses a single USB-C port for full power and control.

• Power draw: ~120 mA at 5V

• Cables included: 0.5 m & 2 m USB-A to USB-C

• No external 12V needed

Software support includes:

• ASIAIR

• ASIStudio

• ASCOM platform

• ZWO SDK-compatible applications

The high-precision stepper motor provides accurate, bidirectional filter positioning for unattended imaging automation.

Compatibility

The EFW-7×2" is ideal for:

• Full-frame mono cameras (ASI6200MM Pro, ASI2400MM)

• APS-C cameras (ASI2600MM Pro)

• Fast refractors and optical systems where 2" filters prevent edge cutoff

• Imaging trains using OAG-L, tilt plates, and spacers that require compact backfocus

Fully compatible with ZWO 2" mounted and 50.4 mm unmounted filter families.

What’s in the Box

(Based on standard EFW-25 series packaging; ZWO may refine per model.)

• EFW Body

• 2" Cover

• 2" Holder

• Threaded Adapter (M54 or M42 depending on kit configuration)

• 2" Nosepiece

• M2.5×6, M2×4, and M4×12 Screws

• 3×75 mm Phillips Screwdriver

• 2" Mounting Bracket

• USB 2.0 Cable (2 m)

• USB 2.0 Cable (0.5 m)

• Filter Masks for 50.4 mm unmounted filters

Imaging Tip

When using seven filters—especially combinations of broadband and narrowband—always rotate through all positions while taking flats. Each filter’s thickness, coating, and seating can affect illumination slightly. Building a matched flat library ensures seamless integration when processing multi-filter image sets from large-format sensors.