This shoot was done to test Elinchrom's high-sync technology when using strobes at shutter speeds faster than the traditional 1/250 limits. The shots were done with an Elinchrom ELB400 kit with a 100cm deep octal soft box.
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View the behind the scenes video here: https://www.youtube.com/watch?v=9WVxgjZy9V8&t=37s
Technical details on high-sync: http://www.elinchrom.com/learn/hss-hs.html