If you’ve ever wondered how to film guitar string waves then you’ll first want to grasp the concept of rolling shutter. The waves of the string are not the actual motion of the guitar strings. Rather, the rolling shutter of the camera is actually what produces this visual effect.
First, let’s clarify what I mean when I say string waves. You may have seen footage of a strummed string creating beautifully accented oscillations, as in the image below:
Initially, I thought the camera was capturing the actual motion of the strings. So I was dismayed when I filmed guitar strings and then slowed down the footage, but did not see any waves!
Then I discovered that using a slow frame rate and a fast shutter speed produced the string waves. So why is that? The waves are actually a visual effect produced by the camera’s rolling shutter.
In a previous post, I’ve explained that rolling shutter is the way that an image is acquired by exposing different parts of an image at different times. If an object is moving fast then the object may be in different location depending on when that part of the image is exposed.
The combination of a fast shutter speed and slower frame rate helps to accentuate the rolling shutter effect. The camera is taking quick snapshots in time for each video frame (fast shutter speed). With a slower frame rate, each snapshot frame will be farther apart in time, meaning the moving guitar string will most likely be in a different location than when the prior frame was captured. When you playback the frames together you’ll see a disjointed wobbly jello like effect.
Not sure what I mean? Check out the video below to see my experiment with filming guitar strings:
Let’s Roll!
In summary, to create the oscillating strings effect use:
- Slow frame rate.
- Fast shutter speed.
