ARRI ARRIFLEX 416 - Manual (Page 45)

Filming with HMI Light
When lighting scenes with HMI/CID discharge lamps, the
intensity of the light will pulse with the power supply frequency
unless a flicker-free ballast is used. To achieve constant
exposure, the camera’s frame rate, the supply frequency
of the lighting and the angle of the mirror shutter must all
relate to each other. As the camera frame rate and the supply
frequency of the lighting are normally fixed, compensation
is achieved by adjusting the angle of the mirror shutter.
The following table indicates the mirror shutter angle that
needs to be set:
Supply frequency 50 Hz 60 Hz
Frame rate 25 fps 24 fps 25 fps 24 fps
Shutter angle
Any angle 172.8° 150° Any angle
Camera
Body
Make sure you compensate exposure for any
change in mirror shutter angle!