I often heard beginning filmmakers make the comment, “I’m shooting at a 1/30 frame rate.” What they really mean though is shutter speed.
I totally get the confusion. There are so many numbers to keep in mind when filmmaking, and a lot of them look and sound the same: 24p vs 1080p; 1/30 shutter speed vs. 30 frames per second. (And it doesn’t help that most DSLRs and video cameras just write “30″ on the display, leaving out the numerator). How do you keep all this in mind? Why should you care? Well, I hope to quickly address that today. (Note: this won’t be an exhaustive post on the topic. But detailed enough to give you what you need to know.)
As the name suggests, frame rate is how many frames per second your camera is recoding. Traditional movie film is shot at 24 frames per second (fps). Although shooting at 24 fps is by no means the ONLY factor to determining a “film look”, it’s a good place to start.
Here’s a list of the most common frame rates you will encounter.
- 23.976 (aka 23.98 aka 24): When you set your DSLR or video camera to 24 fps, you are actually recording at 23.976 frames per second. Believe it or not, it’s an important distinction. Here’s a perfect example why: I once had a project I was editing in Final Cut Pro 7 and my audio kept drifting (i.e. the audio in my media was coming out of sync WITH ITSELF!). For the life of me I could not figure out why. It took me a month of research to finally find the answer (thanks to the amazing filmmakers on CreativeCow.net). FCP uses the notation 23.98 in the program. So when I transcoded the footage using MPEG Streamclip, I set the frame rate to EXACTLY 23.98. But what FCP was calling 23.98 was really 23.976. That minute difference between my EXACT 23.98 footage and the 23.976 sequence settings in FCP was causing the audio to drift in my project. I now keep the frame rate box empty when transcoding with MPEG Streamclip, causing the footage to be transcoded at it’s native frame rate.
- 25: PAL, which is used in many European and Asian countries
- 29.97 (aka 30 fps): NTSC, used in the U.S. and some European and Asian countries. Click here for a PAL/NTSC country list.
- 30: In truth, 99.9% of the time when you hear “30 fps” it’s really 29.97. However, when the 5D Mark II first came out, it’s 30 fps was ACTUALLY 30 frames per second. It was rather frustrating to be honest. Canon eventually “fixed” the situation and included a firmward update that set the 5D2′s “30″ to 29.97. But some of you out there may have a 5D2 that is still shooting 30 fps.
- 48: this is the infamous frame rate in which Peter Jackson shot “The Hobbit.” The verdict is technically still out as to whether it was a success. But the overwhelming majority of professional and critical feedback I’ve seen says it was not a look people liked.
- 59.94 (aka 60 fps): this is double 29.97, and like the aforementioned frame rate, when you see 60 fps, 99.9% of the time it’s really 59.94. This is the frame rate you would shoot at if you want to create realistic slow motion. The slow motion is achieved when you convert 59.94 footage to a slower frame rate like 23.976. So, if you’re editing a 24 fps project and use 60 fps footage converted, you achieve a 40% slow motion rate. This is always preferred to just slowing down your footage in your editing program because when you do that, the computer has to interpolate the difference and “add” extra frames. This can cause what’s often called “ghosting.” When you actually shoot at a higher frame rate then slow it down, you get clean slow motion. WARNING: Almost all of the video DSLRs only shoot 60 fps footage at 1280×720 (aka 720p). That means if you want slow motion in a 1920×1080 (aka 1080p) project, you will need to blow the footage up 150%. This was one of the frustrations filmmakers had with the C300 when it came out. We all want 60 fps at full 1080p. (The Sony FS100, a camera 1/2 the price, shoots 60 fps at 1080p. But there are other trade offs if you use a camera like that.)
The opening 40 seconds of this video we produced for a high performance gym is an example of 60 fps footage in a 24 fps video:
Here’s an excellent example of slow motion taken to the max, in this video by filmmaker Tom Guilmette:
Shutter speed relates to how slow or fast the shutter on the camera is opening/closing. The faster the shutter speed, the LESS light that gets into the camera. The slower the shutter speed, the MORE light.
For the most part, you will want to choose a shutter speed on your camera that is twice the frame rate (technically, it’s the denominator that is twice. So if you’re shooting at 24 fps, ideally you want to shoot at 1/48 (or just 48 on your settings). This is called shooting at a 180 degree shutter angle. I go into more detail on this here. But suffice to say that you do this in order to achieve a normal motion blur. Shoot at a shutter angle above or below that, and you can get a weird look. Shoot at a higher angle and you get that staccato look (made famous in “Gladiator”). Shoot at a lower angle, you get a more dreamy look.
Note: since many DSLRs and video camcorders do not have a 48 shutter speed setting, you would set it to 50 (1/50th) to get as close as possible to a 180 degree shutter. Likewise, if you shoot at 60 fps, make sure to change your shutter speed to 120 (or the closest thing to it) if you want to maintain the 180 degree shutter at that higher rate.
Here’s an example video I made showing the different shutter angles and the effect they have on your footage:
Learn the Rules First, Then Break Them
All of this info is filmmaking basics. For some of you it’s old had. For others, it may be a breath of fresh air. Wherever you fall on the experience spectrum, it never hurts to go back to basics. And once you know them, then break the rules all you want for creative reasons.