In the UK most television cameras are set to record 25 frames per second (the same rate as our television signal). A sequence recorded at 25 frames per second played back at 25 frames per second will appear as "real time" to the human eye. Classic wildlife films have long used high-speed photography and time-lapse photography to play with time.
These techniques allow wildlife filmmakers to reveal aspects of animal behaviour and showcase the beauty of the natural world. For example, running cheetahs or leaping salmon are often shot with high-speed cameras recording 120, 200 or even 1,000 frames per second. When this is played back at 25 frames per second the action unfolds in slow motion – sometimes referred to as slomo.
This technique was used for Planet Earth to reveal a crocodile strike in powerful detail. A high-speed camera filmed 1,000 frames per second, slowing down the action 40 times to reveal the action your eyes would have missed at 25 frames per second.
Time-lapse and lapsed time
For events that take place over extended time periods, the opposite approach is taken. A setting sun or opening flower are often filmed by recording one image (frame) every few seconds, one per minute or even one per hour. Most commonly this is done on digital stills cameras. This technique is called time-lapse, and when these images are edited together and played back they appear to speed up time.
In recent decades time-lapse techniques have allowed wildlife filmmakers to unlock the dramatic world of plants. Sometimes environmental factors (e.g. wind) mean these images require stabilising, or there may also be big differences in sunlight that affect exposure between frames and need smoothing out. But by filming plants for days and weeks, rather than just hours they come to life, like this woodland time-lapse that took two years to produce for the Life series.
Time-lapse techniques have become more sophisticated thanks to the ingenuity of cameramen. Hugh Miller designed and built a rig to film sea ice growing underwater into "brinicles" for Frozen Planet.
Hugh’s timelapse rig produced startling footage of a phenomenon few even knew existed.
Lapsed time, or time study, is a variation of time-lapse used to show change over very long periods of time by filming the same shot at regular, predetermined intervals. It can be filmed at a normal frame rate and then the sequences of shots that are taken are edited together to show the change.
The key to this technique is being able to shoot from the exact same position with the same camera, lens and tripod combination every time. There are various ways to achieve this ranging from a fixed scaffold pole to mark the position, to fiddling around with lots of tape measures. It is very easy to get it wrong. The Great British Year used this technique to show different areas of Britain changing over the course of a year.