What is rolling shutter and why does it happen? If you have ever filmed something on your phone and found that the resulting footage looked completely different than what you recorded, then rolling shutter may be the culprit. Whether this type of shutter plagues your footage or you just find the effect interesting and what to know why it happens, we’ll be answering all of your questions.
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What is Rolling Shutter
Rolling shutter explained
Rolling shutter is quite a complicated, scientific phenomenon. It is a tricky concept to wrap your head around. Do not worry if you don’t fully understand why this happens after the definition, we will be going into more detail and explanation throughout this post.
ROLLING SHUTTER DEFINITION
What is rolling shutter?
Rolling shutter is a type of image distortion that occurs when the motion of a subject is moving too fast for the camera’s sensor to capture properly. The effect can also occur if the subject is static but the camera is in rapid motion. This is not the same as motion blur, though the two are likely to occur simultaneously. Rolling shutter is a more extreme distortion of the image caused by the shutter of certain cameras that can make subjects appear to change shape while in motion.
Some cameras, such as those with CMOS sensors do not capture the entire frame of their image in a single instant. Instead, they make use of what is known as a rolling shutter, where the image is captured progressively as the shutter rolls over the sensor. This rolling motion usually occurs from top to bottom. For more on camera sensors, read our full-frame vs. crop sensor comparison.
Rolling Shutter Explained:
- A type of image distortion
- Progressive scanning of the image
- Requires motion in the subject or the camera itself
Rolling Shutter Effect
Why does rolling shutter happen?
Rolling shutter is a complex and potentially confusing visual phenomenon, but all you really need to know is that the effect comes down to the type of sensor and shutter your camera has. You should also understand the concept of shutter speed while you're at it.
For more detail, refer to our breakdown of the pros and cons of different camera sensors. The video below offers an excellent visual representation of the distortion effect caused by this type of shutter.
As the video above illustrates, the rolling shutter effect is likely to be present in photos and videos captured with a cell phone camera. Check out our list of the best cell phone cameras on the market.
But, this distortion can also occur in any camera lacking what is known as a total shutter or global shutter, which is when the entire sensor is exposed simultaneously. This is opposed to the progressive action of a rolling shutter camera and you can see the difference in the image below.
Total shutter avoids the rolling shutter distortion effect by capturing the entire image at once. For more examples and explanation, check out this video.
The above video scientifically explains why certain sensors capture images differently. If you want to avoid this effect in your own photos and videos, it is worth looking into the type of sensor a camera has before making a purchase. And, if you are looking to make a purchase, be sure to read through our digital camera buying guide first.
Of course, as you've seen in these examples, you might actually capitalize on this distortion effect. If you're looking to create surreal imagery in-camera and skip the time and energy to do it in editing, this might work for you. The key is to know when you want this type of rolling distortion and when you don't. When you better understand your equipment, your mastery over the image gets even stronger.
What is Shutter Speed?
Hopefully, the above information gave you a solid understanding of what shutter speed is and why it occurs. But, there is still more to learn about shutters. A deep knowledge of camera shutter speed is vital to anyone with a serious interest in cinematography. Learn all about shutter speed and its relationship to the exposure triangle, up next.