Metz Mecablitz 34 AF-3M - Manual (Page 12)

6. Flash synchronisation
6.3 Second curtain synchronisation (REAR)
Some cameras offer the facility of second shutter
curtain synchronisation.
With normal synchronisation, the flash is fired pre-
cisely after the opening of the first shutter curtain.
When using slow shutter speeds, and with moving
objects, this would result in an unnatural rendition
of light traces.
With second curtain or rear curtain synchronisati-
on, the flash is fired as the exposure is ending, just
before the second curtain covers the film again.
This makes the light trail behind the moving
objects instead of appearing in front of them, and
renders a more natural looking picture.
11
First curtain Second curtain