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

 

 

 

 

 

Make sure you compensate exposure for any change in mirror shutter angle!

Camera Body

45