Canon EOS 6D Basic Manual page 91

Long Exposure Noise Reduction
Noise reduction is possible with images exposed for 1 sec. or longer.
[Auto]
For 1 sec. or longer exposures, noise reduction is performed
automatically if noise typical of long exposures is detected. This
[Auto] setting is effective in most cases.
[Enable]
Noise reduction is performed for all exposures of 1 sec. or longer.
The [Enable] setting may be able to reduce noise that cannot be
detected with the [Auto] setting.
Select [Long exp. noise
1
reduction].
Under the [z4] tab, select [Long
exp. noise reduction], then press
<0>.
Set the desired setting.
2
Select the desired setting, then press
<0>.
The setting screen closes and the
menu will reappear.
Take the picture.
3
The image will be recorded with noise
reduction applied.
3 Noise Reduction SettingsN
91