Astronomy Specialist

QHY CFW3 SMALL FILTER WHEEL 7 x 1.25" & 7 x 31mm


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The QHY CFW3 Small is a motorized filter wheel designed for 7 filters with a size of 1.25" and 7 unmounted filters with a diameter of 31mm. It uses a high quality ultra-thin hybrid stepper motor that compared to standard electrical motors, is more precise as it has a smaller stepper angle. The motor is enclosed to prevent dust from entering, thus improving reliability and the durability of the motor. The QHYCFW3 main body is CNC machined from a single piece of aluminium, sandblasted and anodized for a high quality finish. 

The QHY CFW3 filter wheels support two connections: 

- the RJ11 port with 4 pin that allows to connect and power the filter wheel to any camera with the CFW port (cable supplied with the camera).

- the USB port for a direct connection to your computer (the USB port must supply 780mA).

The CFW3 has standard USB and a dedicated RJ-11 port for connecting to a QHY camera.

There is an internal switch to select one of the two connection modes and the external LED shows which mode has been selected:

- if the external LED light flashes red for one second, the filter wheel is in USB mode. 

- when the LED light flashes green, it is in RJ11 port mode.

The direction of rotation can be reversed clockwise or anticlockwise to quickly select the desired filter. The stepper motor turns the filter wheel by a friction drive with zero backlash. 

All the QHY filter wheels have a female dovetail ring for the QHY cameras. Under this removable ring the CFW3 Small filter wheel has a standard M42 x 0.75 female connection. 




Compatible filters 7 x 1.25" and 7 x 31mm
RJ11 4 pins / USB
Power draw 780 mA max
Power supply RJ11 cable connected to QHY camera with CFW port or USB cable (must supply 780mA)
Control RJ11 or USB (change mode using the internal switch)
Maximum thickness of the filter 5.5 mm (excluding the filter thread)
Optical thickness with QHY dovetail camera adapter 19.5 mm
Optical thickness  without QHY dovetail camera adapter 15.5 mm
Camera connection
QHY dovetail camera connection and female M42 x 0.75
Telescope connection M42 x 0.75 female
Camera compatibility QHY 183 M/C, QHY 163M/C, QHY 294M/C
Weight 419g

CFW3 Small Ultra Slim version schematic.

Connection diagram for CFW3 Small-US with M42 All-in-one adapter kit.
  • Filter Wheel body
  • M42 to 2" adapter
  • USB cable
  • 4-pin RJ11 to 5.5-2.1 female jack to power filter wheel if USB cannot supply enough amperage
  • 4-pin RJ11 control cable for QHY cameras (CFW port)
  • M3 screws for OAG
  • M4 thumbscrews for connecting camera (100mm & 35mm)
  • QHYCCD sticker



   Features of the CFW3 Filter Wheel.  

Demonstration of the various ways of connecting the filter wheel to different equipment.



Guide to installing QHY and ASCOM drivers for QHYCCD cameras.


ZWO camera software QHY CFW3 driver

ZWO camera software QHY CFW3 manual

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