Canon MARK IV User Manual (en)

 Flash Photography
With an EZ/E/EG/ML/TL-series Speedlite set in TTL or A-TTL 
autoflash mode, the flash can be fired at full output only.
Set the camera’s shooting mode to <a> (manual exposure) or 
<f> (aperture-priority AE) and adjust the aperture setting before 
When using a Speedlite which has manual flash mode, shoot in the 
manual flash mode.
Sync Speed
The camera can synchronize with compact, non-Canon flash units at 1/300 
sec. or 1/250 sec. or slower. With large studio flash units, since the flash 
duration is longer than compact flash units, set the sync speed within 1/125 
sec. to 1/30 sec. Be sure to test the flash synchronization before shooting.
PC Terminal
The camera’s PC terminal can be 
used with flash units having a sync 
cord. The PC terminal is threaded to 
prevent inadvertent disconnection.
The camera’s PC terminal has no 
polarity. You can connect any sync 
cord regardless of its polarity.
Using Non-EX-series Canon Speedlites
Using Non-Canon Flash Units
If the camera is used with a flash unit or flash accessory dedicated to 
another camera brand, the camera may not operate properly and 
malfunction may result.
Do not connect to the camera’s PC terminal any flash unit requiring 250 V 
or more.
Do not attach a high-voltage flash unit on the camera’s hot shoe. It might 
not fire.
A flash unit attached to the camera’s hot shoe and a flash unit connected to 
the PC terminal can both be used at the same time.