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NOISE REDUCTION
Image noise becomes more apparent when using higher sensitivi-
ties, particularly on uniform dark areas. Long exposure times may
cause severe image noise. In order to reduce this annoying phe-
nomenon, the camera will take a second "dark frame" (taken with
the shutter closed) automatically after a shooting with slow shutter
speed and high ISO value. The noise metered in this parallel image
is then digitally "subtracted" from the data for the actual image. In
such cases the message
Noise reduction in progress...
with a relevant time value.
The doubling of the "exposure" time must be taken into account for
long-term exposure times. The camera must not be switched off
during that time. We recommend disabling Noise Reduction to allow
shooting multiple frames in series and to apply noise reduction later
during the post-editing stage. The images will have to be taken in
raw data format.
156
PHOTOGRAPHY ▸ SHUTTER TYPE
Under certain conditions, noise reduction will always be active as
long as the function is enabled. That includes shots taken with the T
function, as well as long-term exposure frames with shutter speeds
of ≥ +8 s.
In all other cases, noise reduction depends on a combination of fac-
tors (specifically ISO setting, exposure time, and sensor tempera-
ture). The following table contains a list of shutter speeds typical for
a sensor temperature of 25°C, at which noise reduction would be
applied.
will appear
ISO
100
200
400
800
1600
3200
6400
≥ 12 500
Noise Reduction can be optionally deactivated (see p. 100).
Shutter speed longer than
7 s
6.4 s
5.9 s
5.4 s
4.9 s
4.5 s
4.2 s
3.8 s
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