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Characteristics of HSS Sympathy Flash
Compared with normal single-burst
flash, the
HSS sympathy flash provides
continuous and constant illumination
for the full duration between the
first curtain opening and second
curtain closing.
The contribution of
HSS sympathy flash to the exposure
of the image is therefore different
than that of a normal flash:
1. The flash output power in HSS
Sympathy mode is different from
that of a normal flash. To
compensate 1EV exposure loss in
your camera setting, you need to
increase the power level of a HSS
sympathy flash by 2EVs. Check the
GN table below for comparison:
Power Level
GN (meter) at 105mm, ISO 100
Normal Flash HSS Sympathy
1/1
56
28
1/2
40
23
1/4
28
20
1/8
20
17
1/16
14
14
1/32
10
12
1/64
7
10
1/128
5
8
to achieve shallower depth of field
while maintaining correct
exposure.
