J'ai posé une question de 2 lignes chez Pocket Wizard, ils viennent de me répondre. Je vous livre ici la réponse in-extenso
C'est agréable de voir des gens qui prennent le temps de répondre de manière très complète. J'attends toujours la réponse de Godox depuis 10 jours...
"Thank you for your interest in our PocketWizard radios! The Plus IIIs are the best radios for remote triggering cameras. For cables, you will need at least one remote camera cable to connect to the remote camera. It turns the radio signal into an electrical signal your camera sees through the remote port.
First of all, triggering from one camera to another is tricky and there are a couple things to know. When a camera gets a signal to fire, it has to say to itself, "am I focused? check! is my exposure ok? check! ok, fire now!", even if everything is set manually. When a flash gets a signal to fire, it says to itself, "oh, fire? Ok, BOOM!"
When you press the test button in your hand, the radio sends out hundreds of packets of information. The physical act of pressing is quite a lot longer than a hot shoe trigger. When you have a radio in a camera's hot shoe, it thinks the radio is a flash. When you are triggering a radio from the camera's hot shoe, it thinks it's just triggering a flash, so it doesn't need very many packets to get the signal out.
That means that the radio on the camera can't sending trigger signals long enough for the camera to focus, confirm exposure, and fire. By the time the camera is ready, the radio's done sending information. That's why manual focus and exposure works best. And honestly, that's what we suggest for remote cameras, plus YOU choose what it focuses on.
There is a slight delay before the remote camera triggers and that is a simple explanation as well. You press the shutter button on the camera in your hand. When the shutter goes, it sends a signal to the receiving radio. That radio then tells the camera to focus and fire. Not quite at the same time, as you can see.
The Plus III radios have a special half press function, on Channels 17 and higher. You would use a remote camera cable on both cameras. When the camera in your hand is half pressed, it sends a signal to the radio in its hot shoe through the remote cable. (Remember I said the normal way, it doesn't send the trigger till the shutter moves?) That radio sends a half press signal to the remote radio, which then "half presses" and pre triggers the camera. It's just like half pressing both shutter buttons at once. Then when you fully press, they're going off at basically the same time. That's the best setup. The Plus III radios also have Long Range mode, which can be helpful in tricky sports setups. For your particular setup, you might need to use Repeater mode. Some cars can give off a lot of RF noise, so what you do is set up one Plus III in between the transmitter and receiver, it will relay signals so you get better distance. Here's a link that shows it in action:
http://blog.joemcnally.com/2012/02/20/new-pocketwizard-plus-iii/One note: you will need to set the transmitting radio to Tx Only and the receiving radio to Rx Only if you use cables on both cameras. You can use just a cable on the remote but you'll get a faster response with cables on both. For the Fuji cameras, you should be able to use our CM-E3-ACC. Doublecheck your manual but I think you can use the microphone port as a remote trigger for the camera, you probably just have to enable it in the menu:
http://www.pocketwizard.com/products/cable_accessory/cameracables/cm-e3-acc/If you want to add in a flash to either camera, you can use a Plus IV as well, this video might be helpful:
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