|f/8, ISO 100, shutter speed: 2 seconds (click the picture to see it larger)|
I recently came across some of Pascal Bovet's images on Flickr and found that he'd linked a lot of his stuff to his website with many of his behind the scenes tricks - and of course I had to try this one out!
Initially I set everything up as he described with one light on my background and one light for the scene pointing down from above (see setup image below).
The basic idea is that you typically hit a ceiling with your flash sync speed somewhere around 1/250 sec. which is fast enough to capture many things, but...not fast enough to capture others.
One way of getting around this is to leave your shutter open longer in a dark environment and trigger your lights manually. A flash burst from your speedlight is a lot faster than 1/250 sec. Using my Nikon SB-24 to light the glass and the strawberry, for example, at 1/16th power gives me a flash duration of around 1/11000th of a second!