It’s one of the most memorable moments in A Scandal in Belgravia. On realising the safe in Irene’s flat is booby trapped, Sherlock yells out a ‘safe word’ that he and John have decided on as an alert to take immediate evasive action: the canon-referencing “Vatican Cameos!” The scene then decends into a slow motion ballet as our heroes disarm the nefarious CIA agents. But how was this stunning imagery captured?

The answer comes from a remarkable piece of camera equipment called The Phantom Camera, manufactured by Vision Research. The Phantom series are dedicated HD video cameras designed purely for high speed photography, and record footage at such a fast frame rate - around 750-1000 frames per second - that when it’s played back at the normal film speed of 24 frames per second the imagery appears to be moving in extreme slow motion.

Commonly used for sports coverage - Phantom cameras were used extensively at the 2012 London Olympics - and wildlife photography, they have become more and more prolificly used for film and television productions, and director Paul McGuigan chose to use one during A Scandal in Belgravia.

Of course, there are some rather important and amusing issues with recording tiny reactions in slow motion while attempting to act, as Benedict Cumberbatch, Lara Pulver and Sue Vertue noted on the DVD Commentary for A Scandal in Belgravia.

Benedict: “It was all over in about two seconds, so it was thrilling to have a look at the monitor afterwards, because the Phantom camera is an extraordinary thing.”

Sue: “And expensive thing”

Lara: “And all of a sudden, you see how your jaw makes the worst, most unattractive shapes.”

Benedict: “Yeah you talk about, having a let’s say, a sexually heightened face, you also apparently have a combat stroke fight face.”

Lara: “And they’re not dissimilar!” [A pause, then quickly adds] “I’m yet to see your sex face Ben, so you’re fine.”

As a true demonstration of the capabilities of the Phantom camera in operation, there’s no better example of this than the videos we’ve embedded below. Recorded by artist David Michalek for a series entitled ‘Portraits in Dramatic Time’, this features Die Hard, Harry Potter, and Benedict-Cumberbatch’s-excellent-impression star Alan Rickman, making a cup of tea.

The captured video runs for over 7 minutes in length, and is indeed rather dramatic, not to mention arresting and hypnotic to watch.

To close though, here is the magic trick: the same footage, returned to normal speed. What was 7 minutes is now a mere 11 seconds long!