Speedlite Transmitter ST-E3-RT Group Mode reverting to ETTL

[Jerrybn]

I am using a 5D Mark II. I have the speedlite transmitter ST-E3-RT on my camera. I have two 600RT flash units set to slave in two groups. On my transmitter I have the mode set to groups and manual. When I take a photo the transmitter reverts back to ETTL mode. Even with it locked. Any ideas how to make it stay in group mode.

[p4pictures]

The EOS 5D Mark II doesn't support group mode that is available on the ST-E3-RT transmitter. If you select group mode on the ST-E3-RT then as soon as you press the shutter the transmitter reverts to E-TTL (this is a Canon design decision). 

You can use the transmitter in manual, and with the ratio set to A:B then you can control the power of two different off-camera 600RT units in groups A and B. Each group can have independent power level set on the ST-E3-RT.