wer224 Loc: Bergen county NewJersey

Hi all I have a canon7d m2 and a600 ex rt my question if I was to leave the high speed sync always on is the effective flash power reduced if you go at sync speed or slower ? Is there any advantages or disadvantages to leaving it always on? Thanks once again bill

GoofyNewfie Loc: Kansas City

I'm sure it switches back to normal mode when it's at or below the regular maximum sync setting.
Nikon does it that way.
I leave mine in Auto FP (Nikon-speak for HSS) all the time.
No reason to turn it off.
That would be really inconvenient.
Canon's smarter than that (eg: radio transceivers in the flash. Something Nikon just started doing.)

speters Loc: Grangeville/Idaho

You can leave it on, because it automatically goes to normal (full) power, once you stay within sync speed!

amfoto1 Loc: San Jose, Calif. USA

Yes, high speed sync reduces the flash's "reach". I would definitely not leave HSS on all the time. The shorter the shutter speed over the camera's sync speed (1/250 with 7DII), the less distance the flash will be effective. At some of the fastest shutter speeds the reduction in the flash reach is dramatic. Some other functions can be used at the same time as HSS, either.... for example, Rear Curtains Sync isn't possible at the same time. The flash will display the distance range on it's LCD, on a scale near the bottom (can be set to read in feet or meters, depending upon your preference).