High Speed Synchronisation Flash Mode - Leica M7 Instructions Manual

High Speed Synchronisation flash mode

If the attached flash unit has the corresponding
function and an SCA-3502 adapter is being used,
the LEICA M7 allows faster shutter speeds of
1/250 s, 1/500 s and 1/1000 s to be used for
flash exposures. This high speed synchronisation
flash technique significantly expands the creative
freedom offered for flash exposures. This is
particularly useful for daylight fill-flashes for
moving subjects, where the desired shallow
depth-of-field requires large apertures and, at the
same time, the high ambient brightness requires
fast shutter speeds.
With standard flash techniques, focal plane shut-
ters like those in the LEICA M7 can only be syn-
chronised with shutter speeds at which the
camera's shutter window is completely open at a
particular point in time. For the LEICA M7, that
means all shutter speeds up to 1/50 s. At faster
speeds, a section of either the 1st or the 2nd
shutter curtain is always in the shutter window,
which means that a flash can never illuminate the
entire image.
However, some modern flash units have "High
Speed Synchronisation – HSS", which emits flashes
of lower power at very short intervals for a short
period of time. As these flashes are emitted
throughout the entire duration of the operation of
the two shutter curtains, and have the effect of a
continuous light source during this time, with this
technique the actual shutter speed is no longer so
critical.
To use the "High Speed Synchronisation flash"
technique, one of the three possible shutter
speeds 1/250 s, 1/500 s or 1/1000 s must be set
manually on the LEICA M7. The light emission
from the flash unit is also manual, therefore the
setting must be made using the flash unit's aper-
ture calculation function. The displays correspond
to those for normal manual flash mode, as des-
cribed above.
For more details, refer to the relevant instruc-
tions.
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