Just recently have tried a few high speed sync flash photos when the subjects are in bright sunlight.
Sunday was meeting with a couple whom i photographing their wedding in November outside on the farm.
Unfortunatley it appears that they will be standing in the sun during the ceremony so took some photos in the sun - harsh at midday....
#1 is normal Apertur Priority F4.5 SS 1/250 28mm on a 24-105mm F4
#2 Swithed to high speed sync and result
F4.5 ss 1/1000 40 mm on a 24-105mm F4 34 seconds later.
A big difference you might say.....
BTW nothing done in PP (LIghtroom) as these are rejected shots...