I just discovered a known issue with the Pocket Wizard firmware for Canon. I use the PW Mini and Flex units. The vast majority of the time, I’m just firing one remote speedlite and it works just fine. The problem started when I tried to add a second 580 EXII onto the camera. In case you’re not familiar, here’s the set-up: The Mini sits on the camera’s hotshoe and triggers the Flex which has a flash mounted on it. I then slide another flash onto the mini. The instructions say that the unit on the mini must be set to “master”. I followed all instructions and nada.
So I called tech support and they told me it’s an issue with the latest firmware (which I faithfully update). They sent me some files where I can revert my units to the previous firmware and told me the next update should clear it up. I just reverted the firmware last night and the system works perfectly.
This may not affect you if you never have a speedlite on camera while triggering another off-camera; I rarely do (mind you, I’m not talking about using an on-cam flash to trigger another as with Canon’s wireless controls or Nikon’s CLS). But the product should work as advertised in the moments when, say, you want to use an on-camera flash for fill. Or another instance that I found myself in when I wanted to use high-speed sync. As you may know, HSS or Auto FP for Nikon users, is a great way to shoot at shutter speeds above your camera’s sync speed (around 200th/sec). But doing so comes at the price of power. So having a second flash firing in HSS (even if it is on camera) is a good way to compensate.
If you’re having the same issues, now you know what it is.