Timelapse calculator

A timelapse sequence will add instant impact to your videos. They can show the audience something magical that could be never seen by the naked eye alone. Even a simple timelapse can be very effective in depicting the progression of a certain subject or scene.

This article will guide you through the process of shooting your first timelapse. By the end, you will learn what kit you need, what subjects work best and the pitfalls to avoid. Plus, you’ll have a simple timelapse calculator that can help you dial in the precision of your sequences.

Timelapse vs. hyperlapse

A video timelapse is a sequence which compresses time so that events which might take place over several hours, or even several days, play back in a matter of seconds. They are filmed at a very low frame rate and the resulting footage is played back at normal speed.

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For a video timelapse, the camera will be stationary, usually locked off on a tripod. A hyperlapse is a timelapse sequence where the camera moves, either panning or tracking to add even more drama to the sequence.

You might ask, why can’t I just shoot a normal video clip and then speed it up in my video editing program? While that could work for shorter timelapse sequences, the file sizes can get impractically large if you are recording an event that lasts for several hours or even days. Shooting single frames also allows for additional shutter effects which are covered in the “Advanced Techniques” section below.

When to use a timelapse

Music videos and art films are ideal settings for the surreal nature of timelapse footage. However, timelapses can work in any genre of film or video if appropriate to the subject matter.

For a documentary, you could use a timelapse to show a skyscraper being built or a flower growing from a seed in a matter of minutes. This would reveal aspects of the process which could never be visible to an observer.

Timelapses should be used more sparingly in fiction films, but they do have their uses. A timelapse could be used to convey the passage of time in an artistic way. In a horror or thriller context, a timelapse showing the sun setting and darkness falling could heighten the tension from an impending danger. A timelapse could also be used for humorous effect in a comedy film, such as a teenager cleaning up after a party at breakneck speed before their parents arrive home.

What do you need to shoot a timelapse?

The first thing to consider is your camera. In the past, still photography cameras were often used for timelapse, as tape-based video cameras could not record single frames. The series of still images would be imported into a video editing program to combine into a moving sequence. However, many digital camcorders, cinema cameras and even smartphones now offer timelapse recording as a standard feature.

For a timelapse, you will need a tripod or some other means of keeping your camera still. Any camera movement will be exaggerated when the clip is played back and result in shaky footage.

If your camera doesn’t have a timelapse recording function, you will need a remote release mechanism. An intervalometer is an accessory which can be plugged into a DSLR still photography camera to trigger the shutter for capturing a timelapse sequence. Some cameras have wireless remote controls which can be used. You don’t want to press buttons on a camera while shooting your timelapse as again, any slight movement of the camera between frames will result in shaky footage.

You will also need to consider how you are going to power your camera. It may need to be on continuously for several hours, so you may need to source higher capacity batteries or use mains power.

What makes a good subject for timelapse?

To be effective, timelapses need to have clear movement in your footage as the main point of focus for the audience. The sun, moon or clouds crossing the sky work well. People walking along a city street or cars on a freeway can take on an entirely new appearance when seen at high speed.

A subject that changes dramatically can also make for an impressive timelapse. An artist might take several hours to paint a portrait. A timelapse can reduce that time to a minute and reveal the nature of the artist’s technique.

Timelapses are at their most powerful when they make visible changes which are normally imperceptible, as they happen over a long time.  

What to avoid

While a moving subject is essential for an impressive timelapse, not all movement in the frame is desirable. Trees and bushes moving in the breeze can appear as a jittering distraction, so try to avoid having them in shot where possible.

As has been said above, it is vital that you don’t move your camera once you start shooting your timelapse. This can be especially important when filming outdoors. You don’t want to ruin your footage when a member of the public accidentally brushes past your tripod five hours into a six-hour shoot.

As timelapses are filmed over a long period of time, changes in exposure can be an issue. This is especially true for subjects such as sunrises or sunsets. However, you should avoid changing the aperture during the recording.

The aperture on electronic lenses will only change in discrete steps which will appear jarring in the finished timelapse. Even with manual, clickless apertures on cine lenses, it will be difficult to change exposure during a timelapse. You may need to shoot some test sequences to determine which f stop will give the best result overall prior to filming.

A personal timelapse calculator

When shooting a timelapse, you can set a random interval for your camera to capture frames and see what you get on playback. However, for more predictable results, you are going to have to do some math. But don’t worry. This simple timelapse calculator will help you know how often you need to capture each frame of your timelapse.

Image of the equation for calculating the frequency of frames to be shot for a timelapse

First, determine how long you want your final timelapse to be. Then, multiply that by your playback frame rate. That will give you how long your timelapse needs to be, in frames.

For example, you want your finished timelapse to last 20 seconds and your playback speed will be 24 frames per second. Therefore, your timelapse needs to be 20 x 24 = 240 frames long.

You then need to decide how long the event you are recording will last, in seconds. For example, if you are filming a sunset you might want to shoot for two hours. Two hours x 60 = 120 minutes. 120 minutes x 60 = 7200 seconds.

Finally, you divide the number of seconds your event will last by the number of frames in your final timelapse sequence. For the above example, it would be 7200 / 240 = 30. Therefore, in this example you need to set your camera to record one frame every 30 seconds.

Advanced techniques

One of the advantages of shooting a timelapse as opposed to speeding up a regular video recording in post-production relates to shutter speed. If you are filming video at 24fps, then your maximum shutter speed is 1/48th second. However, when recording a timelapse, you might only need to shoot one frame every 30 seconds. This means you can use much longer exposures to create lines of light when filming stars or car headlights for example. The latter can be very impressive if your camera is mounted in a moving vehicle at night.

Other interesting effects can be created by juxtaposing a slow element against the fast-moving parts of your timelapse. For example, you could have a person stand very still on a busy sidewalk. When played back everyone else in the frame would be travelling at high speeds while they were motionless. You could even experiment with having the person walk very slowly. One playback they would appear to move at normal speed while again the world raced round them.

Time to start shooting

The subjects you can shoot for a timelapse are limited only by your imagination. Part of the excitement of the process is that you won’t know how your timelapse will look until you play it back. So start practicing and experimenting, and you will soon be wowing your audiences with your magical timelapses.

Pete Tomkies is a freelance cinematographer and camera operator from Manchester, UK. He also produces and directs short films as Duck66 Films. Pete's latest short Once Bitten... won 15 awards and was selected for 105 film festivals around the world.