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Arri WCU-4 Wireless Compact Unit

Abel Code: wcu4
Mfr. Code: K2.72103.0
A 3-axis lens controller with a 3" LCD to track lens data. This follow focus features a compact and ergonomic housing for all day use.
Key Highlights
  • 3-axis control in a lightweight body
  • Transflective display technology
  • Backlit focus knob


Weighing around 1.7 lb, including the battery, the ARRI WCU-4 Wireless Compact Unit is one of the lightest hand units on the market. It provides durable, all-day comfort and reliable, 3-axis lens control (iris / zoom / focus) and remote start/stop recording, and other camera settings. Although the product name says wireless you can also hardwire this unit to your camera if you prefer to operate that way.

Several features on this WCU will assist your lens control.

Vibrating Markers

Tactile, vibrating feedback lets you keep your eye on the action in the most challenging situations. The hand unit vibrates to prompt when markers are reached or when a camera alert occurs, such as for a nearly full recording media or low battery voltage. ARRI's theory with this is that with the backup of a vibrating marker, you can focus on the action on set instead of the location of the focus marker. 

Map your lens scales to an optional, pre-marked focus ring available in metric or imperial scale.

Backlit Focus Knob

The smooth focus knob contains an integrated light source which shines through the wide focus ring in low light conditions to provide clearly readable focus marks. You can adjust the knob friction to your preference without use of tools. A white focus ring is included with this unit. If you prefer, explore the expendables to find camera and lens accessories within the same color family.

You can dim or brighten the illumination of the focus knob (and the display), as needed.

Lens Data Display

Well-arranged yet still easy-to-read lens and camera information can be viewed on the large 3” LCD on the unit body. Transflective display technology ensures perfect readability in all ambient lighting conditions.

You can find data from optional ultrasonic distance measurement devices here, too. 

Six soft buttons below the LCD change their behavior depending on screen content. A convenient label will appear above the buttons at the bottom of the screen. If there is no label, that button has no function from that screen.

This controller includes the ability to adjust:

  • Frame Rate
  • Shutter Angle
  • Exposure Index
  • False color on monitor output
  • ND Filter (on/off)
  • White Balance

Extended camera status information is also available for a quick confirmation of camera settings, such as battery levels (with intelligent batteries which feed data to the camera), which recording codec is in current use, plus the name of the lens attached.

Activate Focus Tracking

Adapt your WCU-4 to add scifi-like functionality by configuring the user button to activate focus tracking. By doing this, the focus motor will continuously follow a subject via an ultrasonic distance measurer. The focus tracking function pairs with the optional ARRI Ultrasonic Distance Measure UDM-1 and an ALEXA Plus or ALEXA Studio camera. You can also use this accessory with the Universal Motor Controller UMC-4.

Remote Control

Add an optional software license to enable remote control of the ARRI ALEXA Mini, and all ALEXA cameras except the ALEXA HD Plus. It also controls the AMIRA when you combine with the Universal Motor Controller UMC-4.


Personalize your WCU-4 to your preferences. You can rearrange the display, use a variety of vibration patterns, or a customize programmable user button, among others. Save your settings on an SD card so you can personalize another WCU-4 on the next project or a rental unit.

You can pair this unit with passive motors, active motors, cameras, ENG lenses, the UDM-1, and a few wireless devices. A wireless antenna on top of the unit is provided. 


Please be sure to calibrate any motors you connect to the WCU-4 under the following conditions:

  • When a motor is detached from the lens
  • After changing motors
  • After changing lenses
  • After a change in motor position while powering down

Calibration is easy: press the CAL soft button on the home screen.

Durability, Power & Updates

The splash-proof ARRI WCU is lightweight for your comfort and durable for long-term use. Power to the unit is provided by a DV/HDV camcorder battery, such as the Sony Lithium M NP-FM 500H. New firmware updates you can retrieve online can be installed to your hand unit via an SD card in seconds.

The ARRI WCU-4 Wireless Compact Unit is compatible with these cameras:

  • ARRI ALEXA Plus 4:3
  • ARRI ALEXA Studio
  • ARRI 416Plus
  • ARRI 435 Extreme equipped with white radio (basic functionality)
  • ARRI UMC-3A with white coded radio modem (basic functionality)
  • ARRI WZE-3 with white coded radio modem

Radio System

Wireless lens control and lens data communication is enabled with a white coded radio module. There are 8 channels to choose from. Here are the associated frequencies for your reference:

Channel 0 - Frequency: 2.410 GHz

Channel 1 - Frequency: 2.415 GHz

Channel 2 - Frequency: 2.430 GHz

Channel 3 - Frequency: 2.435 GHz

Channel 4 - Frequency: 2.450 GHz

Channel 5 - Frequency: 2.455 GHz

Channel 6 - Frequency: 2.470 GHz

Channel 7 - Frequency: 2.475 GHz 

NOTE: Please check local regulations when you travel as some countries limit wireless radio operations. You can switch the radio off and use the device in hardwired mode when unsure of regional restrictions and settings.


Software Update:

ARRI has released Software Update Package (SUP) 3.2 for the Wireless Compact Unit WCU-4. ARRI highly recommends updating the WCU-4 to this Software Update Package. This SUP adds the following new features and changes:

  • Support of the OCU-1 or Master Grip override function
  • Custom white balance values
  • User button assignment
  • Lens Data source switch
  • Lens Data format switch between metric or imperial scale with the cforce mini RF lens motor
  • Clear active lens file (LDA) from the hand set

What's in the Box

  • 1 x Arri WCU-4 Wireless Compact Unit


Key Highlights

  • 3-axis control in a lightweight body
  • Transflective display technology
  • Backlit focus knob
  • Vibrating markers

Compatibility - Camera

ARRI Arriflex 435 Xtreme - equipped with white radio (basic functionality)
ARRI 416Plus
ARRI UMC-3A - with white coded radio modem (basic functionality)
ARRI WZE-3 with white coded radio modem


Input Connector/Port:
SD Card - Use for software updates & saving user preferred settings for use on other WCU-4 units

Mechanical & Electronic Controls

Focus Knob:
Handheld Wireless - LED backlit rotary knob with adjustable friction. 3" diameter. 16-bit native encoder resolution.
Controls Include:
Focus Knob
Iris Slider - Fully sealed, splash- and dust-proof slider mechanism. 14-bit native encoder resolution.
LCD Display - Transflective TFT LCD. 3" diagonal.
Zoom Knob - Force sensitive knob with ergonomic design for comfort.


Monitor Brightness:
Daylight Visible


Power Input:
Battery Pack - or via LCS cable through an ARRI camera (cable mode)


11 in
11 in
15 in
4 lb
Tutorials & Guides
Tutorials & Guides
Tutorials & Guides

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