Everything you need to know about frame rates
What is frame rate?
It's the number of consecutive images (also called frames) needed to achieve real-time motion. In a nutshell: the number of images per seconds.
Common frame rates
Here's a list of popular frame rates and where and when to use them:
1-15 FPS: Hyperlapse or timelapse. (No speed ramping, but better quality) Also used in old films and animations.
24 FPS: This is your go-to FPS. Is used widely by almost every filmmaker and is an industry standard. Commonly referred to as the most "Cinematic” one. Use this for dialogue or shots that doesn't need manipulation in post, like landscapes to keep the maximum amount of details. (this is normally the best quality image you'll get)
25 FPS: The refresh rate used by the PAL system. Used mainly in Europe for television.
30 FPS: It's the NTSC refresh rate (29.97 to be exact) so widely used in television and shows. Can also be used as your frame rate for cinematic sequences, it's really up to preferences. Otherwise, you can conform it to your 24p timeline. It's gonna slow time down to 80% and create a dream-like effect.
48 FPS (HFR): Rarely used in cinematography, a rare occurrence is The Hobbit. From this point on, it looks ultra realistic.
60 FPS (HFR): Used in sports or high action scenes, it removes unwanted motion blur. if used in movies it feels very weird. It looks very digital as the frames are smooth and the details are sharp. Your normal slow motion. Useful to make a moment last longer. Example: A couple looking at each other on a wedding, you want them staring into each other for longer. Or: slowing down action shots.
120 FPS (HFR): Very slow motion. The frame rate used for speed-ramping. Almost stops time. Also useful to remove camera shake too. it degrades quality as well since you're spreading your mbits/s across much more frames.
240 FPS + (HFR): Extremely slow motion, but footage loses quality drastically. An entry-level camera like the Gopro can achieve this.
Basically, if you always shoot with post-production in mind, you'll always have the highest available image quality for the type of shot you want.
Motion blur & SHUTTER SPEED
Motion blur is the streaking or trailing in an image. it's either caused by the camera or an object moving.
A good rule of thumb while filming is to have 1 over double your frame rate as your shutter speed. Why? It replicates the 180-degree shutter angle from cinema which was studied to be the most realistic and pleasing kind of motion blur for the human eye. You could go for a higher shutter to get more details in your shots and have less blur. Or have a lower value to get more motion and induce a dreamy effect. If you shoot at 24 FPS, we would use a 1/50 shutter speed. If you shoot at 60 FPS, we would use a 1/120 shutter speed.
*If your shutter speed goes lower than your frame rate, your video will lag and have stutter, not good, it also won't look good. EX: shooting at 24p with a shutter of 1/20.
Refresh rate & why 30 is a good fps
Most modern computers and phones have a refresh rate of 60Hz. It means that the screen refreshes 60 times per seconds, very similar to 60 FPS don't you think? This is the reason why, if you have a keen eye, every video that's 24 FPS on modern media has stutter or also called "drop frame”. 60/24 = 2.5, it's not an even number, it means some frames are lost, with 30 FPS, it's an even number 60/30 = 2, you got no frames that are lost. You can always use 24FPS, there's a technology called "frame interpolation” which, in a nutshell, your video stutter is less noticeable, but it's still visible.
Keep in mind
For films or videos, frame rates higher than 30p starts to look ultra-realistic and unnatural, look up the "Soap Opera Effect”.
Your shutter speed should almost always be “1 over double your frame rate” to keep natural motion blur. (That's why ND filters exist for videos)
High frame rate (60 FPS+) are meant to be slowed down in post.
Important notion to REMEMBER
If your clip frame rate can't evenly be divided by your project frame rate, it also can't be played back in real-time without stutter.
60 FPS/24p = 2.5 ✘ 120 FPS/24p=5 ✓
Even though it's possible to use it this way, it is not optimal, as you lose image quality (mbit/s) & your motion blur isn't 100% optimal.
120 FPS/24p=5 ✘ (Low quality footage) 24 FPS/24p ✓ (Maximum quality footage)
What a headache, now what should I use?
Most people will use 24p or 30p as their frame rate. It's up to you. For me, I would rather go with a 30 FPS rate as my videos are always played back by modern technology. But you might want to go for 24 FPS, your film might be played on a projector or some TV.
"But what frame rate should I shoot with?” A failsafe frame rate would be 120 FPS, it can be played back in regular time on both 24p and 30p. Can also be slowed down. But it will also span your mbits/s on 120 frames if your camera doesn't adjust for it. You are also not going to get natural motion blur, images will be sharper. It's a good all-around run and gun FPS, kind of the lazy filmmaker choice, I would still use it if I wasn't sure which one to use. Also here's a cool flowchart :)
Remember that it's not all about the frame rate! Filmmaking is an art that has more to it. Like color grading, Composition, music, etc…