Nikon Autofocus Speedlight SB-24 - Manual (Page 109)

When making multiple exposures, there are many factors to be
considered. You may want to experiment before making the final
exposure.
Background brightness
If the subject will move across a relatively dark background, the
exposure settings can be as indicated by the SB-24 LCD. If the
background is rather bright in relation to the subject, however,
the subject will appear faded in the final picture. We suggest
you try to underexpose the background to make the subject
stand out.
Subject overlap
If the flash frequency is so fast that each image of the subject
will overlap, the portion of the film where the subjects overlap
will become overexposed. Try to choose a flash frequency that
avoids subject overlap or use a smaller aperture to set the
exposure conditions so each exposure of the subject will be
underexposed. The overlapped portions will then be less
overexposed, but the non-overlapped portions will be darkened.
This type of experimental photography is exciting. For consist­
ently rewarding results, we suggest you keep notes of all
settings and conditions for future reference.