Nikon FG Instruction Manual page 47

Electronic flashes are convenient not only for night
or low-light shooting but also as a supplemental light
;0
fill in shadows in the daytime. When shooting with
electronic flashes such as the Nikon Speedlights
S8-18, SB-16B and SB-15, the FG's shutter speed is
automatically switched to 1/90sec. on P, A and on
l1anual modes when the manual shutter speed is
1/125sec. or above . If the manual shutter speed is
1/60sec . or below, the shutter will operate at the set
speed . The Nlkon FG directly accepts the Nlkon
S8-18, SB-16B and SB-15 which have an ISO-type
hot-shoe mount, and the SB-12, SB-16A and SB-17 via
Ine Flash Unit Coupler AS-6 . Be sure to check the
guide number of the flash unit and set the aperture to
match the shooting distance. The sync contact of the
FG is an X-contact only and synchronizes at the
speed of
1/90sec .
or slower. Flash bulbs can also be
used at the following shutter speed sync ranges:
Sn ..
d I<J
SDf~~d I S<O',
~1
10001,
")ObV25QT1!125"90
l i60 1/30 1
l~
1/8 14 1:2 1
47