Nikon SB-28 User Manual
Page 55
Exposure compensation in Repeating Flash Mode
The flash shooting distance calculated in step number 4 is the correct
exposure for the first flash in the sequence. Therefore, repeating flash at
this flash output level will result in overexposure of the overlapped images.
To prevent this, use a smaller aperture.
NOTE
Use fresh or fully charged batteries when performing repeating flash.
Allow enough time for the flash to recycle between each repeating flash.
55