Behind the scenes on Sanctuary

Sanctuary is one of the only television series to shoot extensively on green screen with virtual sets. Here we see a shot pre-visual effects (VFX)...

...and after

Working with so many green screen shots means the actors have to stretch their imaginations if they're to visualise what will be added later. So what are Will and Helen looking at?

They're right in the heart of the Sanctuary. This scene, from episode one, is where Magnus first reveals the true scale of the Sanctuary to Will

Will and Magnus talk on the Sanctuary's ramparts

But only now do we get a sense of the scale of the building

Helen's feisty daughter Ashley...

And here's the final shot

This is what was actually filmed for this shot of the ramparts

Pull back a bit...

...and here we have the final shot, illustrating what a tiny portion of the frame is taken up by the filmed sequence

Sitting the other side of the camera are director/executive producer Martin Wood (left) and co-producer/VFX supervisor Lee Wilson

Director of Photography David Geddes in action

The crew filming a shot of Ashley with her bike

It's a hell of a lot of gear for just one shot...