I've done wedding photography for years. With µ4/3 I almost always use available light, but I was going to shoot a surprise birthday party in a dark restaurant and decided to use my OM-D & Metz AF50-1. Although I tried everything out at home, I was primarily checking exposure and didn't pay enough attention to the small delay between pressing the shutter button and the exposure being made in TTL flash mode. The time it takes to fire the pre-flash, measure the light and then take the exposure is long enough to make it very iffy to get fleeting expressions. The Metz only has TTL and manual mode, so I switched to manual mode which has no delay. When I got home, I tried the little Olympus flash that comes with the OM-D, and that has the same delay in TTL mode: it's not a Metz issue. In the future, I'll use my Nikon flashes in Auto mode people photography.