KEY POINTS:
Shots from the air are stunning, thanks to what is known as a Cineflex Camera Stabilisation System attached to a helicopter.
With old equipment, animals were scared off by the noise of approaching helicopters but the Cineflex allows the camera operator to shoot from an altitude four times higher than normal.
The kit has been widely used on feature films, commercials and news programmes, but this was the first time it was used for a nature documentary.
The camera was operated by Michael Kelem, who was aerial director of photography on Mission: Impossible, via a joystick.
The system's camera is stabilised by gyroscopes and housed in a 35cm diameter ball mounted in the helicopter's nose.
Compared to bulky 35mm-film camera systems, the Cineflex is fairly lightweight.
"It has a lens four times more powerful than any we had used before, and without it we would not have been able to shoot scenes such as the wolves hunting, as they are notoriously shy, nervous animals," says Alastair Fothergill.
"Equally, we were able to film the migration of the humpback whales in rough seas, and the polar bears stranded on the ice."
