Canon MARK IV User Manual (en)

: Setting the ISO Speed
If the ISO speed is set to “A”, the actual 
ISO speed to be set will be displayed 
when you press the shutter button 
halfway. As indicated below, the ISO 
speed will be set automatically to suit the 
shooting mode.
Default ISO Speed
* If the shooting mode is <d> and bounce flash is set with an external Speedlite, 
ISO 400-1600 will be set automatically.
* If fill flash results in overexposure, ISO 100 or a higher ISO will be set.
About “A” (Auto) ISO Speed
Shooting Mode
ISO Speed Setting
ISO 100 - 12800
Fixed at ISO 400
With flash
Fixed at ISO 400*
With [8C.Fn I -3: Set ISO speed range] (p.208), the upper and lower limit 
settings and ISO Auto setting will work as follows.
In d/s/f/a shooting modes
Even if the upper limit is set to H1, H2, or H3 and the lower limit to L, ISO 
100-12800 will be set automatically.
If you narrowed the upper and lower limits from the default setting, the 
ISO speed will be set automatically within the range you have set.
With bulb exposures and flash photography
If ISO 400 is not within the upper and lower limit, the ISO speed will be 
set close to 400.
Even if [8C.Fn I -3: Set ISO speed range], [8C.Fn I -12: Set shutter 
speed range
] (p.211), or [8C.Fn I -13: Set aperture value range] (p.211) 
is set to limit the settable range, if [8C.Fn I -8: Safety shift] (p.210) is set 
to [1: Enable (Tv/Av)] or [2: Enable (ISO speed)], a setting outside the 
limited range might be set to obtain a correct exposure.