SIGMA SD1 - Manual (Page 55)

54
SLOW SYNC
When using the flash with P/A mode, the shutter speed value, which will
reduce camera shake, is set automatically. The slow synchro mode
changes the shutter speed up to 30 second depending on light condition.
This mode is suitable for a portrait in a nightscape.
It is possible to set the slow synchro mode from [
Capture Settings] (P.28) →
[Slow Sync.] or the Function Display (P.35).
Off
(Default)
Default setting is applied.
z
Please use this mode for ordinary photography.
On Slow synchro mode is applied.
REAR CURTAIN SYNCHRONIZATION (FLASH SYNC. MODE)
When you photograph a moving subject with slow synchronization, usually the
furrow of the subject will be exposed in front of the subject. The ordinary flash
light will fire when the front shutter curtain is fully opened, thus the subject will
be exposed from the time the flash is fired to the time the shutter is closed
(Front curtain synchronization). When you use rear curtain synchronization,
the flash will fire just before the rear curtain begins to close and the subject will
be exposed by ambient light from the time the shutter opens until the flash
fires. As a result the furrow of the subject will be recorded behind the subject.
This gives a more natural effect.
It is possible to set the rear curtain synchronization from [
Capture Settings]
(P.28) → [Flash Sync. Mode] or the Function Display (P.35).
(Default)
Default (Front curtain synchronization) mode is applied.
z
Please use this mode for ordinary photography.
Rear curtain synchronization mode is applied.
z When using the optional flash SIGMA EF DG SUPER series, please set this
function on the flashgun. (It is not possible to use rear curtain synchronization
when the external flash SIGMA EF DG ST series is attached to the camera
body.)