I have a related question. Currently I have one pair of YN622C and one 600exrt. I use it as fill flash mainly.
I would like to explore more on flash photography. But I am not ready to commit to buying another 600exrt yet. What I'm willing to invest is probably 300-500 for two more flashes. I think I want to get another pair of YN622C and two YN flashes. My question is which model I should get such that they would work with my 600ex as a master. I see many different models and I can't really tell the difference.
5DMK3, M5, 24-70 2.8L II, 16-35 F4L IS, 70-200 2.8L IS II, 35F2 IS, 135L, 70-200L F4 IS, 600EX-RT x2, 430EX RT, EOS M IR converted, efm 11-22, efm 28 macro, efm 18-150