Nortonski wrote in post #18284223
See the
LINK
Canon state that HSS (using the ST-E3) only works on bodies from 2012, it does not work on older bodies like the 1DIV.
I have used it on both my old 5D3 & now the new 5D4 bodies without issue.
EDIT: whilst the ST-E3 doesn't offer Optical, the YN-E3 does...(I only have the ST, so haven't tested the YN)
As an early investor of the 600 EX-RT ST-E3 RT System, three stated Scenerios of pre 2012 cameras have been listed.
However two have been shown and have worked in my 7D Version 1.
Sync Speed, one stop less than Camera Sync. False, camera worked just fine at 1/250.
High Speed Sync. False. While indicator Warning appeared on ST-E3 RT transmitter, images are recorded just fine past SyncSpeed.
GROUP Mode, True, does not work.
Group Mode is one of the luxuries of investing in the 5D Mark III in 2013.
You may want to do the Human Test on your Mark IV.
I just pulled out the 7D a few minutes back to prove what we found in 2012.
Canon 5D Mark III (x2), BG-E11 Grips, Canon Lenses 16-35 f/4 L IS, 17-40 f/4 L, 24-70 f/4 L IS, 70-200 f/2.8 L IS II, 70-200 f/4 L IS, 70-200 f/4 L IS Version II, 100-400 f/4.5-5.6 L IS Version II, TS-E 24 f/3.5 L II, 100 f/2.8 L Macro IS, 10-22 f3.5-4.5, 17-55 f/2.8 L IS, 85 f/1.8, Canon 1.4 Extender III, 5 Canon 600 EX-RT, 2 Canon ST-E3 Transmitters, Canon PRO-300 Printer