Do you need a wireless TTL cord?
A company called Pixel and located in Shenzhen, China has just launched radio triggers that it calls “wireless TTL cords” and that it claims is compatible with the TTL of Nikon's and Canon's dedicated flash systems.
The units are known as as TR-331 (Nikon), and TR-332 (Canon).
Details are sketchy at the moment, and the “English” text on Pixel's home page is machine translated gibberish that does not make much sense. However, according to the specifications, it communicates on the 2.4 GHz frequency (unregulated worldwide), provides 15 selectable channels, and works at distances between transmitter (TX) and receiver (RX) up to 65 meters. The units uses CR-2 3 V lithium batteries (2 in the transmitter, 1 in the receiver),
Early users report that the units are compatible with TTL, but that the “cord”-reference should be taken literally. It is a replacement for an off-camera flash cord, not for PocketWizards, RadioPoppers, or the light-based systems that Canon and Nikon use to control several remote flashes wirelessly.
What the Pixel device is supposed to give you, is the ability to transmit the camera's menu settings that apply to a flash positioned in the hot-shoe, to an off-camera flash. I.e.: Any changes made in the flash menu on the camera are sent to the off-camera flash and appear on the flash menu display as though the unit were sitting in the camera hot-shoe. This means that you should be able to remotely control functions like FP / HSS, red-eye-reduction, slow sync, rear sync from the camera's menu.
According to report from early users, it does not let you run the flash connected to the RX unit in Nikon's commander mode. If this is correct, it means that you can't use it for hybrid set-up where you control a commander Speedlight by radio, and use this to control several groups of remotes by light.
Is it possible to buy additional RX units and control more than one remote Speedlight with this system – using TTL to control the power of the remotes? According to Pixel, there is no communication between RX units so presumably each RX unit act as if it is alone. The camera's TTL light-sensor should “see” the cumulative output of all the pre-flashes. Will the TTL-computer be able to interprete this cumulative and compute the correct power setting? I don't know, but I would love to get my hands on some units to try this out.
However, this is not likely to happen. The units typically sell on eBay for USD 160 for a transmitter/receiver pair, with USD 100 for each additional receiver. That is too stiff for me to just buy some for trying out purposes. Unless somebody lend me a kit, I will not have a chance to try these out.
I think TTL is overrated anyway. The poverty wizards kit with one transmitter and five receivers I bought for USD 80 back in 2005 still serves me well.
For a comprehensive report from a user of the Nikon version, see Dennis Dixon's blog.
