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F. ISO, Gain and Dual ISO
F3. More information on the Dual ISO function
The FX9 has a very useful Dual ISO function that allows the
camera’s sensor to operate at two base sensitivity levels. In
Custom mode the two levels are denoted as Hi and Low and
in the Cine EI mode the two sensitivities are 800 ISO and
4000 ISO.
Dual ISO is very different to the conventional addition of
gain used in most cameras to change the brightness of the
recorded video. In conventional cameras, when you add
gain to increase the ISO, not only does this make the images
brighter but it also increases the noise levels. Adding 6dB of
gain or doubling the ISO via gain will make the recordings
twice as bright but it will also make them twice as noisy.
Adding gain may also result in decreased dynamic range.
Because the Dual ISO function works by altering the
operation of the sensor to make the sensor more or less
sensitive, when you use the Hi Base ISO function the images
do not become significantly nosier, nor is there any change
to the dynamic range or colour response. The image quality
is almost exactly the same whether you choose the Lo Base
or Hi Base mode. The only difference is a very small increase
in noise in Hi base compared to Lo base.