First of all, the system seems independent from the camera's wireless flash system (such as Nikon's Advanced Wireless Lighting). Briefly, the system appears to allow radio TTL and manual capability with remote adjustment.
There is a commander unit called the YN460-TX (which looks like the Nikon SU-800). The TX commander is designed to be attached to the camera hotshoe and apparently can emit an AF assist light. However, it also appears that the TX can be used off-camera (query whether the TTL capabilities would remain). According to Yongnuo, the TX commander can control up to 16 dedicated speedlights (YN460-RX), each of which has built-in radio capability.
HOW IT'S USED:
The TX commander controls 3 groups simultaneously: a TTL group (TTL), Manual group 1 (M1), and Manual group 2 (M2). To assign an RX flash to a group, you press the RX flash's mode button until the RX selects WT (for the TTL group), M1, or M2. In addition to the WT, M1, and M2 mode, the RX unit has another wireless mode, WX which allows it to function either on manual or TTL, as explained below.
Group M1: once an RX flash is assigned to M1, its power level can be selected by choosing the M1 group on the TX unit then adjusting the power level. There are 7 power levels, in full stops from full power to 1/64 power. There are no power indicators per se -- you have to count the number of LEDs lit. 1 LED = 1/64, 2 LEDs = 1/32 etc.
Group M2 functions similarly. Its power is selected by choosing the M2 group on the TX and adjusting the power level.
Wireless TTL: This was not clearly demonstrated in the videos. It appears that TTL flash exposure can be adjusted from -3 to +3 FEC. The video demo'd adjustment of FEC directly on the RX flash. The videos did not demo wireless adjustment of FEC with the TX commander, though it seems the TX commander should have this capability because its LEDs are labeled -3 to +3, which wouldn't make sense except for TTL.
WX mode of the RX flash: In WX mode, the RX flash will match the CURRENTLY SELECTED mode of the TX commander. By contrast, if the RX is in WT mode, it will stay assigned to the TTL group, and if it is in M1 or M2 mode, it will stay in M1 group or M2 group respectively. On the other hand, by using the RX flash in WX mode, it can join group WT, M1 or M2 as needed. If the user wants the RX (on WX mode) to join the TTL group, then the user simply has to remember to switch the TX to TTL mode when he is ready to shoot. If the user wants the RX on WX mode to join the M1 or M2 group, the user simply switches the TX to M1 or M2 respectively immediately before shooting.
The WX mode is useful when you only have one RX flash, allowing you to switch from TTL to manual anytime. It is useful also if you want one of your RX flashes to be flexible and join any of the other groups as needed.
- Uses 2.4ghz frequency. Up to 200m range claimed.
- 7 available channels. (By contrast, Nikon's Advanced Wireless Lighting has only 4 channels.)
- Supports rear curtain sync, flash exposure compensation (FEC) and "FEB" (flash exposure bracketing??)
- There is a blue LED light to show that a link between the TX and RX has been established.
- The TX appears to have 2 ports, one of which appears to be a PC sync.
- The RX flash can also function on non-wireless manual mode. It is not clear whether it can function as a non-wireless TTL flash.
- LightingRumours.com, citing De.Rec.Fotografie, states that cost will be 200 euro for a TX and RX kit. Availability is estimated to be within the next 2 months, direct from Yongnuo's ebay site with a 12-month warranty: http://stores.ebay.com/hkyongnuophotoequipment .