Canon EOS Rebel T5i 18-55mm IS STM Kit Instruction Manual page 128

3 Noise Reduction SettingsN
[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 otherwise
cannot be detected with the [Auto] setting.
With [Auto] and [Enable], the noise reduction process after the picture is
taken may take the same amount of time as the exposure. You cannot
take another picture until the noise reduction process is completed.
Images taken at ISO 1600 or higher may look grainier with the [Enable]
setting than with the [Disable] or [Auto] setting.
With [Auto] and [Enable], if a long exposure is shot with the Live View
image displayed, "BUSY" will be displayed during the noise reduction
process. The Live View display will not reappear until the noise reduction
is completed. (You cannot take another picture.)
128
Set the 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.