Canon EOS M Instruction Manual page 147

Depth of Field PreviewN
The aperture opening (diaphragm) changes only at the moment when
the picture is taken. Otherwise, the aperture remains fully open.
Therefore, when you look at the scene on the LCD monitor, the depth of
field will look narrow.
You can check the depth of field with the procedure below.
1
Enable depth-of-field preview.
Under [54: Custom Function
(C.Fn)], set [6:
to [1: Depth-of-field preview] 1: Depth-of-field preview 1: Depth-of-field preview
(p.287).
The Custom Function setting The Custom Function setting The Custom Function setting
procedure is explained on page 282. procedure is explained on page 282. procedure is explained on page 282.
2
Exit the menu. Exit the menu. Exit the menu.
3 3 3
Press the <XL> button. Press the < Press the <
X X X The aperture will stop down and you
can check the depth of field.
f: Changing the Depth of Field
XL button function]
L L
147