Introduction

When shooting high speed video, one of the most important question to begin asking is, What frame rate will you be shooting at? That’s because your frame rate will determine so many aspects of your production. Like how much light you’ll need or what resolution you’ll be at. So we’ve teamed up with VIA Films in order to demonstrate how your frame rate can affect the rest of your production.

Why Frame Rate Matters

At first you might think it’s easy to decide what frame rate to shoot at. But, depending on what exactly the action is in front of the camera, you might want a faster or slower frame rate.

The first question to ask is, How long will the event will be in front of the camera? Generally the shorter the event, the faster the frame rate. An example might be a bubble bursting or a water drop falling.

How fast is the subject moving? The faster the subject moves, the faster you should film. A bullet traveling through an apple requires a high frame rate otherwise you’ll miss it completely.

When you are playing back the clip at 24 frames per second, how long should the action play on screen? The longer it needs to play back, the faster you should film.

So for example, if you have a 1 second event that needs to play back for 2 seconds, film at 48 frames a second. If you need it to play back for 30 seconds, shoot around 700 frames a second.

Knowing these specifics will help you select an appropriate frame rate for what you are filming, which in turn will help you select the best camera for your project. You’ll also know what type of lights you’ll need for your scene. As you can see in these examples that we shot in the studio, increasing the frame rate can have a dramatic affect on what we see in the shot as well as how the shot feels or plays in the edit. That’s why choosing the best frame rate is the most fundamental step of shooting high speed video; it’s the one factor that can drastically affect the rest of the shoot.

Suggested Frame Rates

So where do you start, and what frame rates are best for different subjects? Well, as a general rule of thumb, whenever you are looking for a slight slow-motion effect, like in sports, or just about any other human action, then typically somewhere around 200 – 300 frames per second will work best. Humans don’t move very fast, so it’s rare you’ll go faster than 300 frames per second; maybe 500 frames per second for some things, but that’s about it. When filming at 300 frames per second, each second you record is going to take roughly 12 seconds to playback at 24 frames per second. So a 10 second event, will take about 2 minutes to view.

Frame rates in the 500 – 2000 frames per second range are most commonly used for liquid splashes, food, objects falling, and explosions. Most mayhem and destruction works well at these frame rates. To achieve these frames rates, you’ll typically need to use a special high speed camera. And at these frame rates, events start to take on unique looks. I’ve found that if you are shooting food, somewhere around 1,000 frames per second looks good. And 1,000 – 2,000 frames per second is great for explosions or most destructive forces. Just remember, a 2 second event will take about 3 minutes to play back if you’re recording at 2,000 frames per second.

Above 5,000 frames per second, you are in the realm of research recording and testing. At these frames rates and higher we can really see the step by step process of the unfolding of an event. At 5,000 frames per second, a 2 second event will take roughly 7 minutes to watch. That’s a lot of content!

Frame Rate vs. Resolution

Unfortunately, when you start going above certain frame rates the image resolution starts to be affected. This is because the camera is processing so much data from the higher frame rate that it can’t maintain a high resolution at the same time. If you need a high frame rate, you’ll need to either settle for a lower resolution image or get a higher end camera. If you can’t sacrifice resolution and don’t have access to a better camera, you’ll need to drop your frame rate down some. So knowing the resolution needed for the project will dictate what type of camera you’ll have to use.

The specs for high speed cameras often tell what resolutions it records at for specific frame rates. If image quality is important to you, also pay careful attention to how the camera samples the sensor at various resolutions. Some cameras just sample a smaller portion of the sensor, which can create a softer image, while other speciality cameras, like the Phantom have the ability to window down the vertical resolution in order to increase the frame rate while the horizontal resolution of the full sensor is still used.

Speed Ramping

Ah, speed ramping. This is probably one of the most common techniques used in many commercials that are shot at high speed. In just about any truck commercial, you’ve seen this effect in action. Speed ramping is where the action starts out in real time, then it magically slows down to emphasize an important action in the shot. An example might be an off-road truck going through a huge mud puddle.

Although some cameras are capable of doing speed ramping in-camera–where the camera records at normal speed then switches to a faster frame rate when you trigger it–I’ve found it more effective to film the whole shot at the high speed frame rate, then adjusting the timing in the edit. Although I’m a big fan of doing everything in-camera, typically we don’t have fast enough reaction times when triggering speed ramps in-camera. The result is that in-camera speed ramp never quite works as well as it does when you do it in the edit.

Final Thoughts

So if you are shooting human action, remember to keep your frame rate somewhere in the ballpark of 200 to 300 frames a second. 500 to 2000 frames a second is gonna be great for the majority of your product shots, uh water, or explosions. But regardless of what frame rate you choose, make sure that you can film at a resolution that suites the project’s needs. The last thing you want to do is choose a frame rate and then be forced into a resolution that doesn’t fit the needs of the project.
I want to thank again Daniel from Via Films for helping us make this series a reality. So what kind of projects are you going to be shooting in slow motion? And what frame rate did you choose? I want to know, so leave a comment below. And if you have any questions, ask away, and I’ll be sure to respond.