Understanding Frame Rate

                                                       Persistence of Vision example

                                                       Persistence of Vision example

Frame rate is the most fundamental part of filmmaking. Having a little background knowledge on what video is and how to record in the right frame rate will help you to create smoother looking films or videos. 

FPS (Frames per second)

We often see the term but what does it really mean? Video is really just multiple photos played back very fast. For films, the standard is 24 photographs (frames) taken per second. When you play 24 pictures that's been taken in one second, you have created an illusion that these pictures are moving thus creating video. This illusion is also known as persistence of vision. This illusion can be achieved at as low as 10fps but this would look jerky and cause a strobing effect much like the cartoon flip books we played with when we were younger. The reason that films use 24 fps is because this syncs to audio rather nicely. Broadcast TV is almost always shot at 30fps.

So to recap, frame rate refers to the number of individual frames that comprise each second of video you record, also known as FPS (frames per second.) The most common frame rates in video are 24, 25 and 30 frames per second.


Slow Motion

When you double your frame rate (48 frames per second) and playback at 24 frames per second, it'll take you twice as long to watch every frame from beginning to end. This is what slow motion is, recording at a higher frame rate so you have more frames to watch at regular speed. This type of filmmaking is usually used to dramatize actions that are happening very quickly such as a hero in a film walking away from an epic explosion or a slam dunk in basketball. Slow motion can make something as simple as walking look cool and allows us to enjoy that epic explosion a little longer. 

Shutter Speed

Shutter speed is just as important as frame rate! I'll explain this simply without going into the history of shutter speed (angle). on film cameras. Your shutter are like blinds on your camera, they allow light in when open and block light when closed. 

Shutter speed refers to the amount of time that each individual frame is exposed for. In video, the shutter speed you use will almost always be a fraction of a second. The number used in setting a camera’s shutter speed refers to the denominator of that fraction of a second. For example, if you set your camera’s shutter speed to 60, that means that each frame is being exposed for 1/60th of a second.

People often make the mistake of equating frame rate with shutter speed. In other words, some people determine that if they are shooting with a shutter speed of 1/100th of a second, that they are in turn shooting 100 frames per second. This is not the case. Depending on the camera you are using and the frame rate you have selected, you are probably shooting at either 24, 25 or 30 frames per second and exposing each individual frame for 1/100th of a second.

As a rule of thumb, you want the denominator of your shutter speed to be approximately double the number of frames per second that you are recording. In other words, if you are recording at 30 frames per second, you want your shutter speed to be 1/60th of a second.

Even though we generally set the denominator of the shutter speed to be double the number of frames per second, you can achieve some interesting stylistic effects by straying from the norm. Shutter speed can have a very noticeable effect on the look of your video, particularly when it comes to motion. A fast shutter speed such as 1/400th of a second will produce a series of crisp frames that have a choppy look when played back. A slow shutter speed such as 1/30th of a second, on the other hand, will produce a series of slightly blurred frames that have a smoother look when played back.

So what does this mean for you?

When shooting with a camera that gives you the ability to change your frame rate. Remember that shooting in 24 frames per second is the standard seen mostly in movies, 30 frames if you want your content to have more of a TV feel like commercials or think of the news. Slow motion will dramatize anything you record.