https://marco.org/2009/02/23/my-new-compact-lighting-setup-not-pictured
My new compact lighting setup. (Not pictured: ST-E2 wireless transmitter on the camera.)
I realized that I frequently need extra light when shooting indoors (especially at home in the evenings), but:
- I almost never want the flash to be attached to the camera — an off-shoe setup makes more sense for me.
- I almost never like the effect of having only one primary light source — I need a multi-point master-slave setup.
- I don’t like the 580EX II for my purposes. It’s too big, heavy, and expensive for me, and its benefits over the 430EX II are mostly unimportant for my use, except its ability to act as a master to other slave flashes — which the ST-E2 can also do.
So for almost the same price as a 580EX II and a 430EX II, I got two 430EX II units and the ST-E2 transmitter to be the on-camera master.