Thanks. Re: flash duration - I do recall that pricier strobe heads like profoto, elinchrom and broncolor are capable of operating near full power with very short flash burst duration 1/1000 of a second and possibly less. The metz 60's probably kick out around 350 watt/sec's each at full power but at duration times of 1/200 of a second (which is plenty fast for candid portraiture at f5.6-f8). For this shot they were set at quarter power which brings the burst duration down to 1/750th.