First: The radio transmitter functions very well and reliably in both directions, as a remote shutter release and a flash trigger.
It can also be both simultaneously, that I can from the remote flash (or if I have three or more transmitters, the third from) trigger the camera and on the same transmitter at the camera the flash is for synchronous timing (ie, when the shutter is open ) is triggered. (In the previous version, you need to at least two pairs on separate channels.)
Channel selection is easily doable by DIP switch in the battery compartment.
Problem # 1: If you put the transmitter in the hot shoe of the camera (because you want to trigger a remote flash) and a dedicated flash puts it, the latter is not operated as a dedicated flash, but only gets a center contact-sync pulse (no A / E -TTL). This also applies to the remote-controlled flash. But since you already have to manually set the flash setting, does not bother, ie problems for studio settings, for rapidly changing conditions as flash remote release hardly makes sense.
Problem # 2: The transmitter can not be locked in the hot shoe. So if you really been attached a lightning above, slips all out very easily. Not recommendable. Better to put the primary lightning separately from the camera on a separate tripod - but you need to nunmal an extra transmitter, in a two-flash setting so 3 transmitters (as a transmitter, two as a receiver) ... stupid!
Otherwise, everything works very very reliable. You have to know whether the offered to their own needs fits precisely.
The offered by Canon flash remote controller is of course in almost all respects superior (except for the scope and direction of independence), but it costs also 10 + fold.
In the long term but you need 3 or more transmitters, so it's fun.
