ZWO EFWmini – 5x 1.25"/31 mm Motorized Filter Wheel

ZWO EFWmini – 5x 1.25"/31 mm Motorized Filter Wheel

Description
The ZWO EFWmini is the most compact electronic filter wheel ever designed by ZWO.
It accommodates up to five mounted 1.25" filters or five unmounted 31 mm filters, with a minimal thickness of 20 mm and a weight of just 300 grams.
The body is precision CNC-machined from aircraft-grade aluminum, combining mechanical rigidity and light weight.

Its stepper motor, manufactured by NPM (Nippon Pulse Motor) in Japan, guarantees long-term reliability, high positioning accuracy, and smooth, quiet operation. The wheel can rotate in both clockwise and counterclockwise directions.

The EFWmini operates using a single USB 2.0 cable that provides both power and control. No external power source is needed. The power consumption is approximately 120 mA at 5 V, allowing seamless use via the USB hub of any cooled ZWO camera.

When used with the ASI1600, the filter-to-sensor distance is approximately 10 mm, allowing:

• No vignetting for 1.25" filters up to f/5,

• No vignetting for 31 mm filters up to f/2.

Technical Specifications

• Filter positions: 5

• Compatible filter sizes:

  • 1.25" mounted (max thickness 7 mm, thread depth < 3 mm)

  • 31 mm unmounted (max thickness 3 mm)

• Stepper motor: NPM (Japan)

• Rotation: bidirectional (clockwise and counterclockwise)

• Interface: USB 2.0 (power + control)

• Power consumption: approx. 120 mA @ 5 V

• External power: not required

• Material: CNC-machined aluminum

• Filter-to-sensor distance: ~10 mm with ASI1600

• Thickness: 20 mm

• Weight: 300 g

• Software support: ASCOM ZWO driver, native compatibility with most capture software (NINA, SGP, etc.)

Box Contents

• EFWmini filter wheel

• 1.25" cover

• 1.25" filter holder with cover and screws

• T2 nosepiece

• Male T2–T2 adapter

• Set of filter masks for 31 mm filters

• USB 2.0 cable (2 meters)

• Phillips screwdriver

• Bag of M2 screws for filter installation

Filter Installation

• Mounted 1.25" filters: thread filters into the holder (thread depth < 3 mm), replace the back cover

• Unmounted 31 mm filters: place each filter flat into its recess, insert washers and M2 screws, then close the cover

Compatibility and Use

• Fully compatible with ZWO ASI monochrome cameras: ASI1600, ASI294MM, ASI183MM, etc.

• Ideal for low-backfocus optical setups

• Safe operation when using ZWO’s recommended filters and screws

• Supports ASCOM driver control with calibration options if needed (up to 60 seconds for full recalibration)

Additional Information

• For balance, when using only some filter positions, distribute filters in slots 1, 3, 5, 7 (on 7/8-slot models)

• No need for proprietary software — works natively with ASCOM

• Silent operation, no electromagnetic interference

• Developed and manufactured entirely by ZWO