How does high speed sync work?

So as i understood it, the sync speed of my camera (XSI, 1/200) is a camera limitation.

But on my 580ex ii... i can do any shutter speed i want.. and from what i've seen, there's no dark areas from the shutter being in the process of opening and closing.

How does this work, is the 580ex ii really allowing me to do shutter speeds above my 1/200, or is there a downside to doing that that i'm not seeing, or will show up in certain shots.

The mechanics of this is confusing, if anyone has a tutorial of high speed flash to help me understand, that'd be awesome.

Yep, it's allowing you to use a higher SS. Because at a higher SS the shutter is never completely open, you need to use HSS. As far as I know, it just keeps the flash on for a longer burst than normal.

I guess it would use more power and cause longer recharge times. I haven't really experimented with it much.

The flash gives off a long (about 1/250s at least I'd think) burst of flashes (at about 60kHz IIRC), so it more or less acts as a continuous lightsource. That includes having a chance of motion blur if the shutterspeed doesn't stop it

funk1196 wrote in post #6099306
The mechanics of this is confusing, if anyone has a tutorial of high speed flash to help me understand, that'd be awesome.

Somebody wrote one.
https://photography-on-the.net/forum/showthre​ad.php?t=208520