Quick fix
Increase the PWM (Pulse Width Modulation) refresh rate on the fixture. On the fixture display, go to MENU > PERSONALITY > PWM FREQUENCY and set it to 12,000Hz or 25,000Hz.
This setting is available on the Focus, Hydro, Encore, and Allegro lines. [confirm: whether any other fixture ranges have this setting]
Diagnostic and resolution procedure
Use this procedure when a camera shows scrolling bands or lines that are not visible to the eye. This is a camera refresh artifact.
Step 1: Identify the camera sensor type
Determine whether the cameras use rolling shutter or global shutter CMOS sensors. Rolling shutters expose scrolling bands when they capture low-frequency pulsed LEDs, so this tells you whether the symptom fits the cause.
Step 2: Open the PWM setting
On the fixture display, go to MENU > PERSONALITY > PWM FREQUENCY. [confirm: whether the on-screen label is "PWM FREQ" or "PWM FREQUENCY"]
Note the current value before changing it, so you can return to it if needed.
The available presets are 900Hz, 1200Hz, 2400Hz, 4000Hz, 12,000Hz, and 25,000Hz.
Step 3: Cycle the frequency and check the camera
Set the frequency to 900Hz and check the camera output for the artifact.
Move to 2400Hz and check again.
Move to 12,000Hz and check again.
If the artifact disappears at any step, the PWM profile is calibrated. Stop there.
Checking at each step shows you which value clears the artifact, which matters for the trade-off described in Step 5.
Step 4: Match the frame rate
If the artifact persists, set the fixture PWM according to the broadcast frame rate:
29.97 / 59.94 fps (NTSC): set fixture PWM to 12,000Hz or higher.
25 / 50 fps (PAL): set fixture PWM to 12,000Hz or match camera sensor clock speeds. [confirm: where the camera sensor clock speed can be found]
If lines still persist after matching the frame rate, lock the camera shutter angle to 180.0° / 1/100s. This gives the camera a fixed exposure window, so any remaining banding is easier to attribute to the fixture setting rather than to a changing shutter. [confirm: the equivalent shutter speed for 29.97 / 59.94 fps, since 1/100s is stated here without a frame rate]
Step 5: Check the trade-offs
Higher PWM frequencies, such as 25kHz, can slightly reduce dimming smoothness at the very bottom of the range (0–1%). At these frequencies the current pulses are extremely brief.
Choose the lowest frequency that completely removes the camera artifacts. This keeps low-end dimming as smooth as possible while still clearing the banding.
Technical background and prevention
LEDs do not dim by lowering voltage continuously. They cycle ON and OFF rapidly using Pulse Width Modulation, and the brightness you see depends on how long the LED is on in each cycle.
A camera captures its image during a short exposure set by the shutter speed, for example 1/50s or 1/100s. If the exposure falls while the LED is in its off cycle, the camera records less light for that part of the frame. On a rolling shutter sensor, which exposes the frame line by line, this appears as dark horizontal bands across the video.
Increasing the PWM frequency pushes the cycle rate far above the camera exposure window. Each exposure then spans many on/off cycles, and the light is recorded evenly.
To prevent the problem, check the PWM frequency against the camera system and frame rate before a broadcast or recording, not during it.