Rolling Shutter vs. Global Shutter: What You Need to Know

If you’ve ever looked into the specs of video cameras or read up on filmmaking gear, you’ve probably come across terms like rolling shutter and global shutter. At first glance, these might sound technical and confusing, but understanding the difference between these two types of shutters can help you make more informed choices when shooting videos.

In this article, we’ll break down what rolling shutter and global shutter are, how they impact your footage, and when one might be better than the other.

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What is a Shutter, and Why Does It Matter?

Before we dive into the two types of shutters, let’s cover the basics: what is a shutter?

In cinematography, a shutter is a device that controls how long the camera sensor is exposed to light. It essentially determines how much light hits the sensor when you take a photo or record a video. In modern digital cameras, the shutter is usually electronic.

The type of shutter used in video affects how these frames are captured and how motion appears in your footage.

The two primary types of electronic shutters used in video cameras are rolling shutter and global shutter.

What is a Rolling Shutter?

A rolling shutter captures the image by scanning the sensor line by line, from top to bottom. Think of it like a scanner slowly moving across a document, capturing one row at a time.

Look at the above image. Imagine each orange box is a pixel (I know it’s not, just stick with me).

If we imagine each orange box is a pixel, our image is made of only three pixels (each on top of the other). As our hero climbs the stairs, the pixels are read one at a time, thereby causing a lag in the final frame.

Don’t let the simplicity of my example fool you. Rolling shutters are more complicated than this, but the analogy holds.

Since the image isn’t captured all at once, fast-moving subjects or quick camera movements can cause distortions. This delay between the top and bottom of the image can lead to a few common problems:

• Jello Effect: Objects wobble unnaturally, as if they’re made of jelly. This often happens when the camera shakes or moves quickly.
• Skew: Straight lines (like buildings or poles) appear slanted or tilted when the camera pans quickly.
• Smear: Fast-moving objects appear stretched or smeared across the frame.

Here’s what they look like:

You’ve probably seen these effects before, especially in videos shot with a cheaper cinema camera. These artifacts have always been traditionally considered bad in cinema.

If rolling shutter can cause distortions, why do so many cameras use it?

The answer lies in the type of sensor used in most modern cameras. CMOS sensors typically employ rolling shutters, which is why many affordable cameras (including mirrorless cameras) use rolling shutter technology.

Rolling shutters allow for higher frame rates and more data to be captured, which is why they’re common in cinema cameras. For many filmmakers, the advantages of CMOS sensors (better dynamic range, lower power consumption, and higher frame rates) outweigh the potential downsides of rolling shutter artifacts.

In fact, the Arri Alexa line of cameras all have rolling shutters, and films shot with these cameras have been picking up Oscars for over a decade.

Here’s a video that shows you the differences:

However, this doesn’t mean rolling shutters are always the best choice. In certain situations, the distortions they cause can be a significant drawback. This is where a global shutter comes into play.

Global Shutter: Capturing the Whole Frame at Once

Unlike rolling shutters, a global shutter captures the entire image all at once, freezing everything in place.

This is exactly what a good film movie camera rotating disc shutter does. All the pixels are read at the same point of time, so we have a whole frame, intact. This means you don’t have to worry about the Jello Effect, skew, or smear. Global shutter cameras produce clean, distortion-free images, even in challenging shooting conditions.

The ideal global shutter doesn’t exist, but electronic global shutters have the potential for the greatest accuracy and uniformity across the frame.

Many people categorically proclaim every camera must have a global shutter. That’s baloney. Obviously the image quality of high end cinema cameras with a rolling shutter is a counter argument to it.

However, for scenarios where frame accuracy is paramount (like aerial cinematography, scientific imaging, or VFX work), global shutters provide a more precise, accurate representation of what’s happening in the scene.

If you’re looking for a camera with a global shutter, check out these cameras:

• Sony a9 III
• Red Komodo-X
• Red Cinema V-Raptor

Here’s a great video that shows you how global shutters can be advantageous:

Why Isn’t Global Shutter More Common?

Given the advantages of global shutters, you might wonder why every camera doesn’t use one. The answer is that global shutters are more complex and expensive to manufacture, especially for CMOS sensors.

Global shutters also have a few technical limitations. For example, they can suffer from lower dynamic range and increased noise, which means they might not perform as well in low-light situations.

Additionally, cameras with global shutters tend to have lower frame rates compared to rolling shutter cameras, which can limit their flexibility for certain types of shooting.

However, the future might only have cameras with global shutters. For now, though, it’s not that important.

When to Use Rolling Shutter vs. Global Shutter

Now that you know the difference between rolling shutter and global shutter, the next question is: when should you use one over the other?

If you have a camera with a rolling shutter of less than 8ms, you can use it for pretty much everything except:

• Very Fast-Moving Action: If you’re filming sports, high-speed action, or fast camera movements, a global shutter will give you clean, accurate images without distortion.
• Fast panning or tilting, or jerky handheld camera work.

If you have a camera with a rolling shutter of more than 8ms, you want to restrict your shots to static or slow moving shots. If you have a film with gimbal or handheld movement, you have to take great care to keep the movements slow and steady, or you’re going to have seriously compromised footage.

Filming with a faster frame rate might mitigate some of this, though then you’ll lose cinematic motion blur.

If you have a camera with a global shutter, you can use it for pretty much anything, as long as you’re happy with the dynamic range and frame rate.

At the end of the day, the choice between rolling shutter and global shutter depends on the specific needs of your project. For most filmmakers, rolling shutter is perfectly adequate.

As camera technology continues to advance, we’re likely to see more affordable global shutter cameras on the market. Until then, understanding the strengths and weaknesses of both types of shutters will help you make the right choice for your next project.