Frame Rate In Cinematography Explained

Frame Rate In Cinematography Explained

INTRODUCTION

Most of cinema unfolds in real time to replicate a version of reality. But sometimes reality isn't the best way to tell stories. What if we wanted to suspend two characters in time while the world around flies by, draw out an iconic, awe-inspiring moment of action, or invoke an anxiety-inducing choppy rapidity. 

In filmmaking we can use the tool of frame rate, frames per second, or FPS, to control how motion is captured and presented on the screen. 

So, let’s unpack this further by first explaining what frame rate is and how it is practically done with a camera and editing software, look at some common frame rates that are standardised in different places around the world, and with that knowledge, take a look at some creative ways that frame rate can be used to tell a story.  

WHAT IS FRAME RATE?

When you shoot a digital video clip it may appear as one single entity, but to understand frame rate it’s important to realise that one clip is actually a representation of loads of individual pictures, or frames.

These pictures give the illusion of motion - hence motion picture. It works the same way as leafing through still images in a flipbook. If you do it fast enough it’ll look like the little picture is moving.

Before digital, all that film cinema cameras were was a big box that took individual photos very quickly at rates such as 24 pictures in a single second. Instead of a page with a picture on it, a frame was captured as a single image onto a roll of film.  

When people talk about frame rate they usually only talk about one thing: how many frames per second a camera is able to capture. However this is only half of it. To understand frame rate properly you need to know that motion can actually be manipulated in two ways. 

One, the capture frame rate refers to how many individual pictures or frames a camera can capture in one second.

 Two, the project or playback frame rate which is set in editing software and determines at what speed the captured frames are played back.

Changing these two variables in different ways can create normal motion, slow motion and fast motion. 

Let’s say a camera’s capture frame rate is set to 24 frames per second. A clip is shot and brought into editing software, where the playback frame rate is also set to 24 frames per second. This results in on-screen motion which appears normal to the human eye.

This time, the camera is set to 48 frames per second, while the project playback frame rate stays at 24 frames per second. When you hit the spacebar and the clip is played, because the capture frame rate is double the project frame rate the motion will appear to be twice as slow as normal. Also called slow motion.

Finally, let’s set the camera to capture action at 12 frames per second while maintaining a 24 frames per second playback frame rate. This time, the capture frame rate is half the project frame rate, and the motion will be sped up twice as fast as normal. This is fast motion.      

Usually, 24 frames per second is set as the base frame rate for a project, and then the capture frame rate is manipulated to change how we perceive motion, but not always. 

Different frame rate bases also exist. But before I dive into what some of the most common of these basic frame rates are, I’d like to thank today’s sponsor that made this video possible, Squarespace.   

COMMON FRAME RATES

There are two common base frame rates that are used for the majority of film and television productions. 

The first, 24p is based on the standard film exposure rate of 24 frames per second that delivers a look that the human eye has become accustomed to. 23.976 is also commonly used as a progressive scan format based on NTSC television. Regions where NTSC is used include North America, parts of South and Central America and Japan. So productions shot for these countries usually use a 24 or 23.976 frame rate as a project base.

The other common frame rate is 25p, which is used for PAL television. PAL regions cover most of the rest of the world, where 25 frames per second are used as the project frame rate. Although these two bases are most common, there are other alternatives, mainly for broadcast TV production, like 50 or 60p.

There have even been odd experiments like the Hobbit series of movies which were shot and displayed at 48fps. Which, contrary to Peter Jackson’s thinking, got quite a bit of pushback. 

Projecting at this higher frame rate means there is less of the standard feeling of motion blur from movement that we as an audience have become used to. Everything is more crisp and slick. Which in my mind makes productions shot at higher frame rates feel artificial, because our eyes are used to perceiving movement in a more natural way with a kind of motion blur.

For these higher frame rate bases remember that we also need to change our capture rate to compensate. So for normal motion on the Hobbit, the camera shot at 48 frames per second. 

To get motion that is twice as slow as real life they therefore have to boost the capture frame rate to double the playback frame rate - which was 96 frames per second.

While those are some of the most  common frame rate bases, let’s go over some popular capture frame rates. As I have mentioned, to get slow motion a common frame rate is to double the base rate. So, 48FPS for NTSC and 50FPS for PAL. 

Then there are also frame rates such as 33 which is somewhere in the middle of standard slow motion and regular speed and gives the feeling of a subtle suspension of time.

Once we get into the higher frame rates they are usually rounded up to numbers such as 100, 120 or 200. 

Then you get extreme slow motion for specialist shots where time almost feels like it’s standing still. This is usually done on a Phantom camera, at frame rates such as 1,000.  

CREATIVE USES

Let’s take a look at three examples where frame rate is used in a creative way. You can’t really talk about frame rate and motion without bringing up the work of Wong Kar-Wai. 

One technique that appears in many of his films is the use of step printing. 

To get this effect with a film camera, they shot with a low frame rate, in this case eight frames per second. Instead of printing each frame one time and getting a sped up effect, he printed each frame three times to fill in the gaps and arrive at 24 frames in a second.

Instead of getting a new picture in every frame of playback, we get three of the same frames, then a new image for three frames, and this pattern continues.

In different contexts it may have different effects, but Wong and his DP Christopher Doyle often used this trick for action scenes with lots of movement. The stutter and motion blur it gives adds a freneticism and wildness to the scenes.

Another creative way to capture action sequences is with slow motion. On 300 this was done for many sequences in the movie to a melodramatic extent. Snyder earmarked specific shots that he wanted his DP Larry Fong to capture in slow mo. This was mainly done at varying frame rates on the Arri 435ES up to about 100FPS and on the PhotoSonics ER for really high frame rates up to 360. 

Using slow motion in this way for action sequences suspends a moment in time and allows the audience to fully appreciate and be awed by the movements of the character that at real speed would be over in a flash.

This slowed down speed also feeds into the focus that the characters themselves have in that moment and shows how keenly they are perceiving the fight unfold. In this case it also further removes the story from the world of realism and places it in more of a comic book like world where the laws of time and gravity are broken. 

Finally, coming back to the king of frame rates, let's take a look at this shot from Chungking Express. There are a few things going on here.

First, because people in the foreground are rapidly rushing by in a blur, we can establish that this was shot at a low frame rate, such as eight frames per second and projected at a base of 24 frames - not step printed like before. This speeds up the motion. 

Second, the two main characters are moving as if in slow motion. This was simply done by getting them to move extremely slowly in real life. So, even though the film is sped up, the characters remain suspended in time. To me, this has the psychological effect of isolating those two characters and showing how detached they are from the rest of the world. They are so alone that time operates differently on them and leaves everyone else a faceless blur. 

It also elevates the relational and romantic bond between them - as if no one else exists in the world.