Canon EOS M Basic Instruction Manual page 212

3 i: Changing the ISO SpeedN
ISO [AUTO]
Shooting Mode
A/C/2/3/4/5/6/G
F
1
d/s/f/a*
With flash
*1: Fixed at ISO 400 for bulb exposures.
*2: Depends on he maximum ISO speed limit set.
*3: If fill-in flash results in overexposure, ISO 100 or a higher ISO speed will be set
(except in <a> mode).
*4: Except in the A, 6, and F modes.
*5: Automatically set within ISO 400 - 1600 (or up to the maximum limit) in the C,
2, 3, 4, 5, and <d> modes if you use bounce flash with an external
Speedlite.
When [AUTO] is set, the ISO speed is indicated in whole-stop increments.
However, the ISO speed is actually set in finer increments. Therefore, in the
image's shooting information (p.256), you may find an ISO speed such as
125 or 640 displayed as the ISO speed.
112
If the ISO speed is set to [AUTO] and
you press the shutter button halfway, the
current ISO speed will be displayed. As
indicated below, the ISO speed will be
set automatically to suit the shooting
mode.
ISO Speed Setting
Automatically set within ISO 100 - 6400
Automatically set within ISO 100 - 12800
Automatically set within ISO 100 - 6400*
3 4 5
ISO 400* * *
2