Learn what a frame rate is, and how different settings affect the look and feel of your video.
Video is really a collection of still images played back rapidly one after the other to recreate motion. The frame rate of a video refers to the number of still images or “frames” taken each second to create this motion. Choosing a particular frame rate has important effects on how your footage looks and feels. Most cameras will typically have options for 24 and 30 frames per second. More advanced models may have options for 60 frames per second. Camcorders will typically offer 60i as an option as well. Action cameras tend to offer even higher frame rates like 120 frames per second. But why choose one over the other? Let’s start with 24 frames per second. While some films may be shot at a higher frame rate, most films today are shot at 24 frames per second. This was not originally a stylistic decision by cinematographers. Instead, it was adopted to solve technological issues. Many producers will say that the “film look” is achieved by shooting 24 frames per second. In reality, it’s just one factor that contributes to it. The high production value of film and great cinematography play large parts in getting a “film” look. But let’s get back to frame rates. In video 24 frames per second is commonly referred to as 23.976 or 24p. Shooting at 24 frames per second tends to give your footage a surreal feeling, which can help the audience stay immersed into your story. It can also be transferred to film without the need for frame conversion. But there are some limitations you’ll have to accept. Fast pans and quick movement across your frame are likely to have a strobing effect, due to the small number of motion samples being taken each second. Let’s take a look at a fast pan of this courtyard. It looks choppy because there just aren’t enough samples being taken each second to result in a smooth, pleasing result. slowing down your pans, or following a subject as they move helps to minimize the effect. A second frame rate choice is 30 progressive frames per second. You may see this referred to as 29.97p or 30p. Shooting at 30p helps to reduce the strobing from fast movements a bit, while retaining a somewhat surrealistic feel. It also works well for broadcast television output. While it improves the strobing over 24p, it still may not be the best choice if your project will require a lot of fast pans. Now we get to the tricky third option, 60 interlaced fields per second. This is commonly referred to as 60i, but may be referred to as 29.97i. While this creates the equivalent of 30 frames, it’s easier to think of it as 60 half frames or fields. In fact the look and feel this frame rate produces is commonly thought of as the “video” look. Footage shot at this frame rate tends to feel more like reality, because motion is sampled 60 times each second. Let’s take a look at the same pan shot at 60i. The increased number of samples makes for much smoother motion. If you’re project is destined for broadcast television, and it will have a lot of fast pans or motion, or you just want your footage have have that “reality” feel to it, 60i can be a great choice. It can also be a good choice if you’re using a lot of existing footage that was shot the same way. but be sure to check out our interlaced and progressive lesson for more on the pros and cons of interlacing. Our next option is shooting 60 progressive frames per second. You’ll commonly hear this referred to as 60p or 59.94p. Choosing this frame still gives your the “video” look, as it uses the same number of motion samples as 60i. but improves upon it by sampling the entire image, which prevents interlacing issues. which works really well for fast moving sports and action. But, many videographers love to use 60 frames per second for a different reason. Footage shot at 60 frames per second can be used to get frame accurate slow motion when played back at 24 or 30 frames per second. Frame accurate means that no frames are being artificially created, and that actual frames from your footage are being used to create the slow motion effect. If you take the 60 frames that were sampled in one second of real time action, and lay them on a 24 frame timeline, it will take 2.5 second to play back, which results in 40% playback speed. Laying those same 60 frames across a 30 frame per second timeline will take 2 seconds to play back, resulting in a 50% playback speed. Here’s a 60p shot being played back at 24 frames per second. You can see that the playback is perfect. In theory, you’d think the best option would be to just shoot everything at 60 frames per second and then just take 24 or 30 of those frames to get the look you want. But the fact that 60 frames can’t evenly divide into 24, and faster frame rates are typically shot with faster shutter speeds means it doesn’t quite work that way. As always, feel free to try it out and judge for yourself. Now lets kick it up a final notch with 120 frames per second. This is actually a fairly common frame rate on action cams, though it’s typically not at full 1920x1080 resolution. This frame rate can give you extreme slow motion at 20% playback rate. Because laying 120 frames on a 24p timeline makes 1 second of real time recording take 5 seconds to playback. this footage was shot at 120 frames per second, and is being played back at 24 frames per second. Everything does look cool in slow motion. Now that we’ve covered the basics of the most common frame rates, it’s time to consider the how using faster frame rates can affect your exposure, motion blur, resolution, and file size. The faster the frame rate you shoot at, the more it will reduce your exposure and motion blur in your footage. This is due to using faster shutter speeds to accommodate faster frame rates. This can be detrimental if you’re shooting in low light situations, and give fast motion in your shots a stacatto feel. This footage was shot using a 24p frame rate using the standard 1/48th shutter speed. To get the same exposure at 60p with a 1/120th shutter, we had to open up a full stop and an additional third of a stop to get close to the same exposure. It’s also important to check the resolution of faster frame rates. Many cameras may shoot 60p or 120p, but it may be at 1280x720 or smaller, which will require upscaling to match your other footage if you’re shooting at 1920x1080. Finally, getting the same quality footage at faster frame rates will require larger file sizes, and more computer horsepower to run properly. We definitely recommend testing these different frame rates out to see the results for yourself. So there you have it, everything you wanted to know and more about choosing and using the right frame rate for your next project.
