Canon Community

Problem solved It's the lock mechanism on the st-e3. When I use it, everything fails. Solution... don't lock it  I'll have the locking system fixed

I have exact this problem (although i use a 5D mkIV). After approx. 15 minutes I get things working... Imagine how I feel with clients/models waiting. - 1 st-e3 with 3 600EX units- used it a year without one errror- no added gel filter holder- often ...