I sure don't know any of the science of TTL vs. ETTL.
But I can say that the Flash mounted ON the T5i hot shoe, works great in ETTL mode. The ETTL just doesn't work if there is a tranceiver placed on the hot shoe, between the camera and the flash.
The T5i is a type A camera using ETTL II. The 430 EX II speedlight supports ETTL II -. the YN 622C transceivers support both ETTL and ETTL II. So they are all supposed to work perfectly together.
Summary:
1. Camera-hotshoe transmitter ----->across room ---> receiver trigger mounted-ETTL flash: all works great.
2. Camera-hotshoe ETTL flash: all works great.
3. Camera - hotshoe trigger - Flash mounted on top of trigger in ETTL mode for pass-through: NO ETTL.
(flash fires ok as pure manual flash, but if I set flash to ETTL, get a totally black picture). Meanwhile, the ETTL settings from the hotshoe tranceiver ARE transmitted across the room to my other transceiver, and the remote OFF-camera flash fires perfectly with ETTL settings.
So the triggers actually work to receive and transmit ETTL 30 feet across the room, but each trigger alone will not pass the ETTL signals 1 inch from the bottom of the transceiver (camera hot shoe) to the top of the transceiver (the transceiver hot shoe, where the flash is mounted).
Question: either
1. I actually bought two YN622C tranceivers both with the same defect? or
2. there is nothing wrong with the YN622C units - they are working as intended (but this doesn't make sense because they claim to be fully compatible with 430 EX II, and claim to have full ETTL pass-through). OR
3. The YN622C units are not working for ETTL pass-through because of some camera, trigger, or flash setting I don't know about.
Thanks for any help you can offer.
The T5i, 430 EX II and YN622C are all very popular amateur products. Hopefully there are lots of people who have used this combination successfully and can point me in the right direction.
