With the availability of the Pixel King radio triggers the first affordable radio TTL triggers where available for the canon system. So I ordered a pack of three receivers and one transmitter from a store in Poland. You can buy them directly from China or Germany but that store in Poland offered them for a price I couldn't resist. Another reasons has been the promised compatibility with the Pixel Opas. But that's a story which I'll tell you in another post.
What is in the Box: in addition to the triggers themselves you'll get a mini stand, a some connection cables for the receivers and a nice bag. The bag is capable holding two units including stand and cables. You can fit in three units if you remove the cables.
The build quality is fair. The kind of plastic they use feels not as rock solid as the plastic of the RF 602s. I'll handle them with care. One of the receivers was not assembled correctly. The USB port didn't work so I had to dissemble the receiver and repaired it. Luckily it is working now. The red auto focus assist light is not aligned to the center of the image. Instead it only assits upper AF points and is therefore nearly useless.
Do they work? Well, this depends. The first test of the set was disappointing. Sometimes the exposure was correct but a lot of time the flashes did not fire or fired with full power. A lot of times the 580EXII shows TTL instead of eTTL. The YN565EX worked even worse. Exposure with a bounced flash was always underexposed. Another test two weeks ago showed no improvement.
But all those symptom are well known. Have a look at the document I linked at the bottom of this page. After reading it I started another try yesterday. And by magic everything worked as expected. Not misfires, not incorrect exposure. So what did I changed? The first and maybe the most important thing: I didn't used a receiver too close to the transmitter. For the first test I mounted a receiver and a flash using a bracket directly to the camera. The second thing: I changed the exposure metering the average instead of evaluative. The last step helps to get the right exposure if you light the scene indirectly. As of today I would consider myself happy with the triggers. I'll use them to shoot the Christmas Eve tomorrow. I'm curious how they will work.
[Update] They worked very well. I used two 580EXII and one 430EXII in group A. They where evenly spread in the room and the exposure of nearly every image was correct. I still have issues using the YN565EX with the King RX but I'm pleased with the result I got on Christmas Eve. Even while bouncing from the ceiling I got no issues. There was no full dump and no speedlite showed "TTL". The next step will be using different groups and manual settings.
Again I left out most of the technical details. Here is a very good review document of the Pixel Kings: PIXEL'S
KING ETTL FLASH TRIGGER
Pixel King Review