Wow, the old "second shooter" theory; yes there was at least one according to a LOT of technical analysis but they couldn't find a smoking gun(s). Maybe Canon engineers can't find the distance information (new theory but lacking juicy sub-plots)?Hmmm... Isn't one of the main differences between e-ttl and e-ttl2 that the latter makes use of focus distance info provided by certain lenses? And wasn't Canon precluded for a long time from making use of focus distance info in their flash systems because of some patent conflict with another well-known camera manufacturer? And didn't focus distance info stop getting reported by the cameras at about the same time as e-ttl2 came out? And wasn't there a second shooter in Dallas in 1963?