Nikon Autofocus Speedlight SB-22 Instruction Manual page 49

4) When shutter speed set on the FE or FM2 is faster
than the flash sync speed. Set the shutter speed to
the flash sync speed or slower one.
5) With the Nikon F-401/N4004, when the built-in flash
and SB-22 are OFF, and when the camera detects
flash is effective, the ready-light in the camera's
viewfinder blinks when the shutter release button is
lightly pressed.
With the SB-22 in TTL, A1 or A2 mode, if both view­
finder ready-light and SB-22 ready-light blink after
taking pictures (to warn that lighting might have been
insufficient for correct exposure), confirm subject is
within the flash shooting distance range and,- if neces­
sary, use a wide aperture or move closer to the subject.
With the Nikon F-401/N4004, for scenes where the
background is extremely bright, the ready-light may not
blink after the shot, even if flash is insufficient for cor­
rect exposure.
With weak batteries, ready-lights blink to indicate insuf­
ficient flash power, even if the subject is within the
shooting distance range; replace batteries with a fresh
set.
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