Canon EOS 90D DSLR Camera with 18-135mm Lens - Manual (Page 176)

176
Flash Function Settings
 Shutter synchronization
Normally, set this to [First-curtain synchronization] so that the fl ash fi res
immediately after the exposure starts.
Set to [ Second-curtain synchronization] and use low shutter speeds for
natural-looking shots of subject motion trails, such as car headlights.
Set to [High-speed synchronization] for fl ash photography at higher
shutter speeds than the maximum fl ash sync shutter speed. This is eff ective
when shooting with an open aperture in <
f
> mode to blur the background
behind subjects outdoors in daylight, for example.
o When using second-curtain synchronization, set the shutter speed to
1/80 sec. or slower. If the shutter speed is faster than 1/80 sec., fi rst-curtain
synchronization will be applied automatically even if [Second-curtain
synchronization] is set.
 Flash exposure compensation
Just as exposure compensation is
adjustable, you can also adjust fl ash output
of external Speedlites.
o
If fl ash exposure compensation is set with the Speedlite, you cannot set the
fl ash exposure compensation with the camera. Note that the Speedlite’s
setting overrides the camera’s if both are set at the same time.