ZWO EFW-5×2" (EFW-5x2-25)

Electronic Filter Wheel · 5 Positions · 2" Mounted or 50.4 mm Unmounted Filters · USB-C

The ZWO EFW-5×2" is the workhorse filter wheel for imagers running larger sensors, wider fields, or fast optical systems where 2" filters are essential. With five oversized filter positions, an upgraded light-blocking chassis, and a slim 20 mm body profile, this next-generation model brings a new level of refinement and reliability to deep-sky imaging setups that demand large filters and precise automated control.

Whether you're building a system around the ASI2600MM Pro, ASI6200MM Pro, or any camera where vignetting must be minimized, the EFW-5×2" gives you the illumination and mechanical stability required for premium full-frame and APS-C astrophotography.

Advanced Light-Leak Protection for Clean, Uniform Imaging

The updated EFW-25 series incorporates ZWO’s redesigned anti light-leak architecture:

• A tightened slot-fit chassis improves sealing between the front and rear plates.

• Dual light-blocking pads reinforce the lateral connection points to reduce stray light infiltration.

• A fully enclosed motor compartment isolates the stepper motor, eliminating a common light-entry path and boosting long-term environmental resistance.

These refinements help preserve the consistency of your flats and background levels across every filter position — especially important for large-format sensors where gradients are easier to detect.

Five Large Filter Positions for 2" Mounted or 50.4 mm Unmounted Filters

This carousel accepts:

• Five 2" mounted filters (typically up to ~7 mm thickness), or

• Five 50.4 mm unmounted filters

The larger aperture preserves edge illumination on cameras with big sensors or fast optics, reducing vignetting and improving field uniformity. The filter disk is CNC-machined from 6061 aluminum alloy for maximum strength and minimal flexure, even with heavy filter glass.

Despite its capacity, the wheel maintains a slim ~20 mm body thickness, allowing it to integrate cleanly into ZWO OAG modules, tilt plates, and full imaging trains with minimal spacing adjustments.

Power, Connectivity & Software Control

Like all models in the new EFW-25 generation, the 5×2" wheel uses a single USB-C port for both power and data.

• Power consumption: ~120 mA at 5V

• Cable included: USB 2.0 Type-A to USB-C

• No external 12V necessary

Software compatibility includes:

• ASIAIR

• ASIStudio

• ASCOM

• ZWO SDK applications

The high-precision stepper motor provides accurate, bidirectional indexing for fully automated, unattended filter sequencing.

Compatibility

The EFW-5×2" pairs naturally with:

• ASI2600MM Pro

• ASI6200MM Pro

• ASI2400MC/2400MM sensor formats

• Fast refractors where 2" filters prevent cutoff at the corners

• Optical systems requiring an OAG + spacers + filter wheel combination within tight backfocus

It is fully compatible with all ZWO 2" mounted and 50.4 mm unmounted filter sets.

What’s in the Box

(Based on the shared EFW-25 series packing standard)

• EFW Body

• 2" Cover

• 2" Holder

• M54M–M54M Adapter (or M42, depending on final configuration—ZWO varies by package; we can update once official box contents are published)

• 2" Nosepiece

• Screws (M2, M2.5, M4 assortments)

• Phillips Screwdriver (3×75 mm)

• 2" Bracket

• USB 2.0 Cable (2 m)

• USB 2.0 Cable (0.5 m)

• Filter Masks for unmounted filters

(If you’d like, we can revise this after ZWO releases the official packing list for the 2" wheels.)

Imaging Tip

When working with full-frame mono cameras, always confirm that your filters sit squarely in their seats — even a slight tilt in a 2" filter can introduce uneven illumination or star elongation at the corners. After installation, rotate the carousel manually before powering the wheel to ensure each filter clears the housing smoothly.