Canon AF514XL-S - Manual (Page 58)

1. The sound Is recorded 18 frames
ahead of the corresponding picture
frame. This means that, if you were to
leave no room between cuts, the
sound for the first eighteen frames of
the new cut would be on the last
eighteen frames of the cut before. For
editing purposes, it is advisable to
shoot one or two seconds longer than
necessary at the end of each cut.
2. When you are recording sound while
filming, plan ahead for how long you
must film based on what you are
recording. Essential sounds, such as
conversations, explanations and
announcements, for instance, must be