LEICA Q3 Digital Camera - Manual (Page 76)

STILL IMAGE SETTINGS ▸ AUTOMATIC OPTIMIZATION 76
AUTOMATIC OPTIMIZATION
NOISE REDUCTION
NOISE REDUCTION FUNCTION FOR LONG-TERM EXPOSURE
In digital photography, the appearance of flawed pixels that can
be white, red, blue or green is referred to as "noise". Image noise
becomes more apparent when using higher sensitivities, particular-
ly on uniform dark areas. Long exposure times may cause severe
image noise. In order to reduce this annoying phenomenon, 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... will appear 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.
Factory setting:
On
▸ Select Long exposure noise reduction in the main menu
▸ Select On / Off
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.
ISO Shutter speed longer than
100 7 s
200 6.4 s
400 5.9 s
800 5.4 s
1600 4.9 s
3200 4.5 s
6400 4.2 s
≥ 12 500 3.8 s