Nikon SB-27 - Manual (Page 86)

86
Glossary of terms
Front-curtain sync flash
In normal flash synchronization, the Speedlight fires at the
beginning of the exposure. The flash therefore fires just after the
front-curtain opens. Rear-curtain sync flash is also possible with
cameras featuring a rear-curtain flash sync mode set on the camera.
(Applicable to all camera groups)
Guide Number
This number refers to the maximum light output in units of GN [ISO
100 . m(ft)]. A guide number is given to help determine the correct
aperture or f/stop value, or flash shooting distance using the
following equation.
f/stop (aperture) =
guide number
flash-to-subject distance (m)
flash-to-subject distance (m)=
guide number
f/stop (aperture)
(Applicable to all camera groups)
Matrix Balanced Fill Flash
This mode automatically controls flash output so as to keep both
subject and background perfectly exposed.
The camera's Matrix Metering System determines the correct
exposure based on ambient light. Flash illumination brightens the
main foreground subject but does not overpower the background.
(Applicable to F4-Series, F-801s/N8008s, F-801/N8008, Pronea 600i/6i,
F-601/N6006, F-601
M
/N6000, F65-Series/N65-Series, F60-Series/N60,
F50-Series/N50, and F-401
X
/N5005)
Monitor Preflash
In Automatic Balanced Fill-Flash with TTL Multi Sensor mode,
immediately after you depress the shutter release button and
before the shutter is activated, the SB-27 fires a brief series of
nearly invisible preflashes known as Monitor Preflash. These
preflashes are detected by the camera's TTL Multi Sensor, then
analyzed for brightness and contrast ensuring optimal exposure.
(Applicable to F5, F100, F90X/N90s, F90-Series/N90, F80-Series/N80-Series,
F70-Series/N70)