Canon EOS M Basic Instruction Manual page 203

Shooting Tips
Change the ISO speed. Use Speedlite 90EX.
To match the subject and ambient lighting level, you can change the
ISO speed (p.109) or use Speedlite 90EX (p.138). In the <d> mode,
the Speedlite 90EX does not fire automatically. In low-light
conditions, turn <ON> the Speedlite 90EX and set [A1: External
Speedlite control]'s [Flash firing] to [Enable].
The program can be shifted. (Program shift)
After pressing the shutter button halfway, turn the <5> dial to
change the shutter speed and aperture setting combination
(program). Program shift is canceled automatically after the picture
is taken*. Program shift is not poss ble with flash.
* If the pointer icon <c> is displayed above the exposure compensation
display, press the <ZO> button to turn off the pointer icon and then turn the
<5> dial.
Check the depth of field.
In Creative Zones modes, if you use Custom Function C.Fn-6 to
assign the <XL> button to [Depth-of-field preview], you can
check the depth of field.
Differences Between <d> and <A> (Scene Intelligent Auto)
In the <A> mode, many functions such the AF operation, are set
automatically. The functions you can change are limited. Whereas with the
<d> mode, only the shutter speed and aperture are set automatically. You
can freely set the AF operation and other functions (p.296).
If he "30"" shutter speed and the maximum aperture
blink, it indicates underexposure. Increase the ISO
speed or use flash.
If he "4000" shutter speed and the minimum aperture
blink, it indicates overexposure. Decrease the ISO
speed.
d: Program AE
103