Canon Speedlite 270EX Instruction Manual page 12

q: Manual Exposure
Select this mode if you want to set both the shutter speed and aperture manually.
As the camera will automatically adjust the flash output level according to the aperture you
set, the exposure of the main subject will be standard. The exposure of the background is
obtained with the shutter speed and aperture combination you set.
Flash Sync Speeds and Apertures Used
Set automatically (1/X sec. - 1/60 sec.)
V
X
Set automatically (1/X sec. - 30 sec.)
W
Set manually (1/X sec. - 30 sec., Bulb)
q
1/X sec. is the camera's maximum flash sync speed.
If you use the <Z> or <Y> shooting mode, the result will be the same as flash shooting
in <V> (Program AE) mode.
10
Shutter Speed Setting
Set manually (1/X sec. - 30 sec.)
Aperture Setting
Automatic
Automatic
Manual
Manual