Canon SPEEDLITE EL-1 Advanced User's Manual page 57

3.
Select <
Press the joystick to the left or right, turn <
select, then push the joystick vertically.
Check that <
Caution
With high-speed sync, the faster the shutter speed, the lower the guide number
becomes. You can check the effective flash range on the LCD panel.
To avoid degrading and damaging the flash due to overheating, the number of
sequential firings during continuous shooting may be reduced with high-speed sync
flashes.
Note
If the shutter speed is less than the maximum flash synchronization shutter speed,
< > will not be displayed in the viewfinder.
To return to normal flash, select <
not displayed on the screen after setting).
>.
> is lit in the viewfinder, then shoot.
> (first curtain sync) in step 3 (<
57
> to select < > to
> is