Yeah I'm trying to sell one of my APS-C lenses if I do I'm going to put the cash in a 580ex or at least a 480ex, but for now this works well for drunkards in a bar, which is what I do once a week. 95% of the time I use natural light. If anything, I can use it on my 35mm's. Never had something beefy like this.
And it's actually a 540ez.