Unveiling the Enigma of 24 FPS: A Century-old Standard

One reason why 24 FPS movies don't make us feel jittery is because of their stability. Unlike games that sometimes fluctuate in frame rate, a movie remains stable at 24 FPS from start to finish, with each frame pacing at 41.7ms. In fact, many old animated movies even appear smooth at speeds of 8-12 FPS (each frame being displayed 2-3 times).

If this stability is disrupted - for example, when watching a 24 FPS movie on a 60Hz TV - causing sudden changes in frame pacing, you'll notice that the movie loses its smoothness. This is most apparent when watching wide-angle scenes with slow-moving objects gliding across the screen; everything seems shaky even though the camera itself is stable.

The third reason is the existence of motion blur in films. But you might not know how it's created. Each frame of a movie is captured by exposing light onto a film reel for 1/48th of a second, and everything that moves within that 1/48th of a second is recorded before the camera shutter closes for another 1/48th of a second to transition to the next frame.

This creates motion blur, which you can easily observe by pausing a scene on your screen. Motion blur bridges the gap between changes in consecutive frames, making everything appear smoothly in motion on the screen.

You might wonder: Why do games only feel smooth at 60 FPS? The notion that 'games are only smooth at 60 FPS' is a misconception - they can be smooth at 30 FPS as long as the time between frames is consistent, without sudden fluctuations like in movies. Console gamers can attest to this, as many games on PS5, Xbox Series X are still running at 30 FPS. The reason why 60 FPS feels smooth is because it's fast enough to create motion blur in the viewer's eyes, even if the original frames themselves don't have motion blur, as you can verify in the video below:

But why 24 FPS?

During the silent film era, filmmakers shot their works without any standards. Many films were shot at 16 to 20 FPS, which is why you often see movements in movies too fast and slightly jerky on screen. American filmmaker Thomas Edison (not the scientist you're familiar with) shot his early films at 40 FPS.

After various studies, it was found that 24 FPS is the minimum frame rate for images to move naturally, without jerking in the viewer's eyes. The higher the frame rate, the better the experience for the audience, as you can see from the current trend of increasing screen refresh rates.

Now, we have a new question: why was the number chosen 24 FPS, rather than 25, 26, or even higher for better film quality? The simple answer is cost. A classic 35mm film reel can record 16 frames per foot and over 1.6km of film is needed for each hour of screening. Despite the film being wound to reduce size, long films still require multiple reels, so classic cinemas need 2 projectors, alternating reels to provide a smooth experience for the audience. Keeping the film at the lowest frame rate possible can help producers save a huge amount of film and significantly reduce transportation costs.

Who has attempted to 'break through' 24 FPS?

Film formats with higher frame rates actually exist, such as Peter Jackson's The Hobbit filmed at 48 FPS. Jackson aimed to eliminate motion blur in grand scenes or fast-action sequences. However, due to audiences being too accustomed to 24 FPS, The Hobbit movies were criticized for being 'game-like' and 'unreal' – reasons why 24 FPS still dominates theaters even though we no longer need cumbersome film reels.

Apart from The Hobbit, there have been other attempts to double frame rates, like the Maxivision 48 FPS format. The Cinerama 'curved screen' format, once popular in the 1950s, ran at 26 FPS, but faced issues such as limited viewing angles, camera positions, and filming complexity, so it couldn't become a new standard, and the last Cinerama theater closed in 2001.

A 60 FPS film format called ShowScan was developed by Doug Trumbull about 40 years ago, but for various reasons, it was never introduced to cinemas, only appearing in theme parks like Disneyland's Star Tours. You can even find standards like 120 FPS in films like Billy Lynn's Long Halftime Walk (2016) and Gemini Man (2019).

Fortunately, these efforts weren't entirely futile. New television standards now support much higher frame rates, for example, ATSC 3.0 supports up to 120 FPS, and many devices can easily recognize and play films with frame rates above 24.

Today's cameras are no longer restricted by shutters, and theaters no longer need cumbersome film reels, so films can now be shot at higher frame rates. Directors can use cameras at 120, 240, or even 300 FPS, then reduce them to 25, 30, 50, or 60 FPS for streaming services, and 24, 48, or 60 FPS for theaters, providing audiences with much better experiences than in the past.

Final Words

With what has been shared in this article, Mytour hopes that you have found some fascinating new knowledge to share with your friends. See you again in other articles about the world and its wonders.

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