Freezing the moment where a balloon bursts was actually far more difficult to do than I first thought. The time frame from where the balloon starts to rupture until only small fragments remains is less than a millisecond and things occur at supersonic speed (the "pop" when the balloon bursts is actually a sound bang). In order to get a short flash burst (to minimize motion blur), the output of the flash had to be set to a low level, which made the lighting setup somewhat difficult.

Even though a flash burst seems short, a 550EX at 1/32 power has its peak just under 200 microseconds (=1/5000s - checked with a photodiode). Given supersonic speed (>340m/s), the motion blur generated will be some 340/5000 = 6.8 cm (minimum). No surprise that there is some blur...
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