I bought an YN600EX-RT in addition to a YN-560EX. I have a 5D Mark III camera and as a result no inbuilt flash. Following instructions, I cannot find any way to make the units work together. The YN600EX-RT does not work as an optical master. And the YN560EX is slave only. I found that if I put one as an optical slave, it fires anyway after the other goes off. So in a way, it works with conditions that they both fire. Could anyone confirm that this method is ok and there is no significant delay between the first and second flash firing?
Could anyone confirm that this method is ok and there is no significant delay between the first and second flash firing?
Yes. If you have one of the flashes in S1 or S2 "dumb" optical slave mode, and fire the other flash on-camera, the two flashes will fire in sync. The thing you have to be careful of is that but the mode of the master flash on-camera has to match the slave mode.
If the on-camera flash is in TTL, then S2 must be used on the slave, so that the slave flash will trigger on the second flash burst (i.e., not on the TTL metering preflash).
If the on-camera flash is in M, then S1 should be used on the slave.
Optical slaving, however, has drawbacks. If the range and reliability of the triggering becomes hard to use, you may want to eventually get a YN-E3-RX to put on the YN-560EX, so you can use the 600EX-RT as a radio master. However, because the YN-560EX is a single-pin manual flash, the receiver will only be able to tell the flash to fire. You won't have any TTL/HSS or power control capability, as you would with a second YN-600EX-RT.