newbie question regarding slave flash

[flyoverfred]

I've ordered a couple of YN-560 flashes and will use them mostly both off camera - i'm going to get some triggers but my question ( as a newbie ! ) is this:

Can I just use one set of triggers (ie trigger on top of camera and receiver on one flash) and put the second flash in slave to trigger the second flash or do i need two sets of trigger/receivers ?

hope that makes sense !!

[canon_shooter]

Generally, you need 1 trigger + N amount of receivers times amount of slave flashes.

[ec11235]

Originally Posted by flyoverfred

I've ordered a couple of YN-560 flashes and will use them mostly both off camera - i'm going to get some triggers but my question ( as a newbie ! ) is this:

Can I just use one set of triggers (ie trigger on top of camera and receiver on one flash) and put the second flash in slave to trigger the second flash or do i need two sets of trigger/receivers ?

hope that makes sense !!

Those flashes have built in optical slave units. You could use the flash in your camera to trigger the slaves. Assuming your camera uses preflashes for the ttl metering, you could use your camera's flash or a ttl flash on camera and just set your yn560's to S2. If you're not using ttl and don't have preflashes, the S setting is a regular slave mode.

If you want no flash from the camera, you could use a sync cord to off camera the initial flash.

You don't really need triggers unless you have no flashes from the camera and aren't using one on a sync cord, in which case you'd need one transmitter and one receiver. The flash that goes off from the receiver can trigger the other ones via the slave modules.