Hello;

I have Canon 30D and 580EX flash , I'm planning to shoot strobe outdoor and would like to use my flash of camera , also I'll get another 580EX II soon .
Which flash triggering system will you recommend ?

Thanks

The Canon TTL "system" is a good place to start.
The Hi Speed Sync feature is especially useful for outdoor work where the shutter speed may be higher than sync speed.

There is a page showing how I use EV and FEC to control background and foreground with HiSpeed Sync on www.digifotografi.com.

If you want a radio trigger, the only two available that include TTL are the new Pocket Wizards or the Radio Poppers.
Both are relatively expensive.

If you are willing to go with manual flash, which means the camera sync speed is a limiting factor, then any radio trigger option will work. One thing to consider with radio triggers is a "processing" delay that makes the effective maximum sync speed something less than the speed in the manual. I have found that a 1/3 stop slower shutter speed generally ensures adequate compensation.

Thanks I may consider PocketWizards , how many unites would I need for two 580EX off camera ?

Read these tutorials of mine: LINK which explain how to use the it so you don't need to buy anything else.

Chuck

Nasser,
Chuck's tutorials include a lot of useful information.
Remember that ETTL is a Canon proprietary signaling protocol.

The Pocket Wizard TTL system and the Radio Popper TTL systems are protocol convertors.
They change the Canon signals from the camera or master flash into radio signals and then convert them pack to an electrical signal on the Speedlite hotshoe contacts.

All they do is replace the light based signaling between Canon devices with radio signals.

As Chuck suggests, start by learning how multi-speedlite TTL works using just the flash units. Then consider whether you want to invest in the radio signal convertors. All they do is replace the light signaling with radio signaling. If the light signaling works for you they add nothing to the solution but cost.