The idea of a CLS hub, while intriguing, has some practical considerations, circuit delays and timing not the least of them.
Example: If we stick to the current three remote groups A, B and C, and we have remote speedlights in all three groups on the upwind side (my newly coined CLS technical term) of the relay hub and additional units in all three groups on the downwind side, and the relay is accomplished optically, how does the on-camera unit sort them all out? The speedlights in Group A on the upwind side of the relay hub are not likely illuminating the same subjects as those on the downwind side. Additionally, the relay hub will begin reporting the downwind units slightly after the upwind units begin and they will overlap. Current optical signaling is limited to one basic channel. Yes, we could do optical frequency division multiplexing, but this would likely drive sale prices beyond anything most photographers would pay. Adding an artificial timing delay in the relay node simply slows down the preflash sequence, which is already fairly long when three remote groups are reporting. See the problems?
As we have already seen with pocket wizards and the Sekonic meters, using radio frequency (RF) signaling requires three sets of different frequencies to cover communications licensing in North America, Europe and Japan. This adds to design and manufacturing costs and higher prices.
The current non-CLS pocket wizards offer vastly greater range and are easily configured. Yes, one must work strictly in manual mode, with no TTL capability, but I shoot that way almost exclusively so it is not a problem for me.
If, by extending CLS, you mean more groups, we already have a solution for that providing you are using SB900 and SB800 units. By placing them all in the SU-4 mode, each individual speedlight can be configured independently of the others and the three group limit disappears. Once again, you are strictly in manual mode with no TTL capability.
At the rate we are going, we will soon need a small, portable USB keyboard simply to configure our speedlights. (grin!)
Much to think about.
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