It's usually a bad idea to use the flashes from
both mounted cameras simultaneously because each flash
fires from a different angle, resulting in strange
lighting and rivalries. However it's possible to use just one
camera's flash in SDM.
The trick is to think of the flash as if it were
the "shutter" for both cameras. Those Canons that allow for
manual setting of the shutter speed are best.
Canon is the only camera company that assigns a "T," for
"Time" setting, while other camera companies refer
to that setting as "S," for "Shutter."
Electronic flash normally fires from 1/1000 second
and faster, so setting yhe cameras to a shutter speed
of say 1/100 will allow the flash from the camera
to fire within the manual shutter setting, which is much slower.
As a result, both cameras should be able to capture
the flash image withing the assigned shutter speed.
In effect, the flash is becoming the
shutter!!
Experimentation with different manual shutter
speeds may provide the perfect combination for decent shots.
This view was made with shutters set at 1/200,
which allowed for my dog, Turmoyle to be well-illuminated,
while darkening the background. As a result,
the background can be exposed according to whatever shutter
speed is used (the faster the shutter speed, the
darker the background). This provides a sort of depth of
field,
regulated by the amount of background illumination
effect.
Marshall
(392K)