Flash Isn’t just for lighting up the dark: it can reveal shadow detail in photos taken during the day. Shooting in daylight often requires a shutter speed faster than the camera’s flash synchronisation speed. This is the fastest shutter speed at which the flash can be used, and ranges from 1/180 sec to 1/250 sec across the EOS range. One option is to work in Shutter Priority and set the fastest sync speed – the camera will then automatically set an aperture small enough to produce a balanced exposure. Canon’s EX Speedlites offer a Highspeed sync mode that lets you select faster shutter speeds.