What is Frame Rate, and why does it matter? (24fps vs. 30fps)
Most Common Frame Rates
For a long time, 24fps or even 23.98 has been the standard frame rate. It was chosen as the lowest frame rate possible for the brain to emulate fluid motion. The main choice of 24fps was a budgetary and technology limitation issue that allowed for film companies to save money on film by shooting 24 frames vs 30 frames. The more the 24 frame rate was used in bigger budget cinema films, the more we would associate that frame rate with being more ‘cinematic’. This frame rate is what most feature films are made at and it is fairly standard that you would expect this frame rate for commercial ad spots or short films. It is most widely used because of the familiarity and the way our eyes render the video.
Very similar to 24fps, 25fps is the standard frame rate in the United Kingdom and any country that operates off 50Hz power. Your use of 24fps vs. 25fps will primarily depend on where in the world you live.
30fps is six frames greater than 24fps, which means that there is 25% more images to be processed in the same amount of time. Because of the increase in frames, it results in footage feeling smoother and is the typical frame rate used for live events, such as sporting events and concerts, live broadcast, as well as soap operas.
This frame rate is 2.5x faster that 24fps (and 2x faster than 30fps) and the results is that the imagery, when played back on a standard timeline, results in the affect of slow motion. Since it’s significantly slowed down, this frame rate is often used to showcase a more cinematic use of motion and is most often used to highlight and emphasize dramatic moments in a scene or film.
Most current cameras today “top out”at 120fps. Twice as slow as 60fps, this frame rate is 5x slower than 24fps and 4x slower than 30fps. This means that you can utilize ultra slow motion to show product detail, highlight key movements, and bring a unique depth to your films. While content shot at 120fps can have a really dramatic affect, because of how far removed it is from a standard timeline of 24fps or 30fps, it’s a frame rate that can be really beautiful in small doses, but can also make your footage hard to use if you’ve overused this frame rate.
So what frame rate is best?
Well, it all depends on what you’re after! Each frame rate has a specific use, so it might be helpful to first ask yourself what you want to film and create. If you need something more cinematic, then 24fps is great. If you want to add drama and depth to it, you can include 60fps or 120fps and play it back in 24fps (either 2.5x or 5x slower than it was filmed).
If you’re filming live events and want a smooth, seamless look, then 30fps might be more of what you’re after. Additionally, a lot of apps (like Instagram ) use 30fps as their standard for filming, so it’s becoming even more prevalent in daily films that you’ll see in your feed. (Rest Assured, Instagram doesn’t conform your 24fps content to 30fps on upload; it retains it’s original frame rate)
So How did we land on 24fps (or 30fps) as a standard?
Great Question—honestly, it’s purely arbitrary and is rooted in film history and economics. The minimum frame rate for the human mind to perceive motion is 16fps. Different scientists over the years have debated optimum frame rates—with Thomas Edison recommending 46fps. But in time, film was too expensive to maintain that frame rate and it kept getting reduced until it finally arrived at an industry standard of 24fps. This, since it is slower than the human eye, is what results in this frame rate being more cinematic overall, while 30fps is smoother and feels slightly more true-to-life.
What’s the difference between Frames Per Second and Refresh Rate?
A refresh rate is typically given to a display rather than a camera/filming system. Measured in hertz (hz), this measures how quickly a screen refreshes or “recycles” an image and usually correlates to the maximum rate that can be displayed on a particular screen.
What’s ALL-I and IPB?
These settings are all about compression. While your specific camera is going to influence to what degree that compression is, the short of it is this: All-I compression is less compressed and creates a higher quality image (and a larger file size). IPB is more compressed and creates a lower-quality image and a smaller file size.