Nikon D300s User Manual page 206

BUsing FV Lock with Optional Flash Units
FV lock is also available with 5B-900, 5B-800, 5B-600, 5B-400, and
5B-R200 flash units (available separately). 5et the optional flash to TTL
mode (the 5B-900 and 5B-800 can also be used in AA mode; see the
flash manual for details). While FV lock is in effect, flash output will
automatically be adjusted for changes in flash zoom head position.
When Commander mode is selected for Custom 5etting e3 (Flash cntrl
for built-in flash,
0
283L FV lock can be used with remote 5B-900,
5B-800, 5B-600, or 5B-R200 flash units if (a) any of the bUilt-in flash, flash
group A, or flash group B is in TTL mode, or (b) a flash group is
composed entirely of 5B-900 and 5B-800 flash units in TTL or AA mode.
II
Metering
The metering areas for FV lock when using optional flash unit are as
follows:
Metered area
4-mm circle in center of frame
Area metered
by
flash exposure meter
Entire frame
Flash unit
Stand-alone flash unit'
Used with other flash
units (Advanced
Wireless Lighting)
Flash mode
i-TTL
AA
i-TTL
AA
. Area metered
by
flash exposure meter
A (master flash)
180
II
See Also
For information on using the depth-of-field preview or AE-L/AF-L button
for FV lock, see Custom 5etting f6 (Assign preview button,
0
296) or
Custom 5etting f7 (Assign AE-L/AF-L button,
CJ
296).