Roxie2401 wrote in post #16666352
At first I guess what has confused me it the difference between "Channels" and "Groups."
Channels is the communication "wavelength", so you don't confuse your lights with someone else's lights. Like at the Olympics, when everybody is trying to set their lights off remotely, some folks were paying for custom PocketWizard channels so nobody else could accidentally trip their lights/shutters.
Groups is a way to subdivide the lights so you can control different groups of lights differently within the same set up.
And are there groups/channels in the new RT system and what is unique about the 7D?
The new RT system allows for five groups instead of three (A:B:C: D:E vs. A:B:C). And with the addition of ID codes, the RT system supports 150,000 "channels" [15 radio channels x 10,000 ID codes; so less problem at the Olympics, then ].
And the 7D is not unique, and is not fully compatible with the RT system on its own. The RT features of things like Gr mode, groups D&E, and ID codes, if you only use Canon gear, is only supported by camera bodies released in and after 2012. The 7D is not one of those.
IF the older flash units had Groups,
They do. But they don't have Groups mode.
....can you explain what you mean by "new Groups mode introduced with the Canon Wireless RT system?" What is different about these new groups vs. the older ones?
Exactly what agv8or said in his post: the groups can now individually be set into different modes, or turned on and off. In the older pre-RT flash system, all groups had to be in one mode (eTTL or Manual), and could not be turned on and off individually. I.e., in the old system, you had to use all eTTL and ratios (A:B:C). In the new system, you can set Group A to manual 1/8, Group B to eTTL, Group C to MULTI, etc. etc....