high speed sync and pc connection

Would I be right in my assumption that high speed sync with a Canon 5D and 550EX is not possible when the flash is connected to the camera by the pc connector. I have tried everything I can think of but looks like it is not possible, I even put the ST-E2 on the camera hotshoe and set it on high speed sync to see if it made any difference, but it didn't.
Any help appreciated.

No high speed sync, no second curtain sync, no multi flash, no E-TTL, no runs, no hits, no errors.

No HSS when 550 is in manual mode, but the ST-E2 can use HSS with the 550 in slave ETTL mode.

Thanks for the replies....looks like a no-goer then

Lotto wrote in post #5862434
No HSS when 550 is in manual mode, but the ST-E2 can use HSS with the 550 in slave ETTL mode.

I have used the ST-E2 with two 550's on manual for HSS at 1/4000 so it must be possible in manual too.

DaveMcBride wrote in post #5863169
Thanks for the replies....looks like a no-goer then


I have used the ST-E2 with two 550's on manual for HSS at 1/4000 so it must be possible in manual too.

Yes, HSS is available with the flash in manual mode but not when it's connected via the PC sync port or any other connection other than a direct or indirect connection to the hotshoe or controlled via an ST-E2 or a flash master.