Canon Speedlite 540EZ Manual page 16

4. Slow Synchro Photography
Slow synchro photography is a method combining flash with a slow shut¬
ter speed to achieve proper exposure of both the subject and a low-lit
background such as a room or night scene. For slow synchro photogra¬
phy with the 540EZ mounted on an EOS camera, use the procedures
below.
During slow synchro shooting, use a tripod to prevent camera shake caused by
slow shutter speeds. y
^ S^0W syncllro Photography in aperture-priority
1 Set the camera to aperture-priority AE mode
(Av),
and set the
desired aperture.
2 Focus the subject.
3 Make sure the viewfinder display is not blinking and that the flash
charge indicator is lit, then take the picture.
The flash exposure of the main subject is automatically controlled by the
TTL automatic flash program.
2" SIow synchro photography in manual exposure mode
1
Set the camera to manual exposure mode
(M).
2 Focus the subject.
3 Set the shutter speed and aperture to achieve proper background
exposure using the camera's exposure level indicators.
4 Make sure the viewfinder display is not blinking and that the flash
charge indicator is lit, then take the picture.
3. Slow synchro photography in shutter-priority AE mode
1 Set the camera to shutter-priority AE mode
(Tv).
2 Focus the subject.
3 Set a shutter speed necessary to achieve proper background
exposure using the camera's exposure level indicators.
Make sure the viewfinder display is not blinking and that the flash
charge indicator is lit, then take the picture.
If a d'fferenf aperture setting is desired, change the shutter speed until
the desired aperture is set.
Controlling the background exposure with the EOS-1 N and EOS-1
The background exposure can be
determined by reading the position of
the exposure level indicator at the
right hand side of the viewfinder.
t Overexposure
<- Correct exposure
4- Underexposure
Flash photo taken in
aperture-priority AE mode
(automatic slow synchro operation)
Flash photo taken in
Full Auto mode