Why when I look at a guitar string when I play a guitar, it vibrates really fast in my eyes but, when I watch a video of [https://www.youtube.com/watch?v=XOCGb5ZGEV8](https://www.youtube.com/watch?v=XOCGb5ZGEV8) with a camera, the guitar string vibrates in a wave that is very noticeable?
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Your eyes are constantly collecting light. If something moves too fast for your eyes, it blurs.
Cameras usually take very short pictures and then wait in between each picture. They also don’t take the full picture all at once, they scan across it from top to bottom, so at different points in the picture the string is in different places and it looks wobbly.
It’s called the “rolling shutter effect”. Named after film cameras that used a shutter that swiped across the film from one side to the other. Phone cameras gather information from their sensors in a similar way. They sample each image in a stripe starting from one side and ending at the other, over and over again, to make a video.
Because of this, something that’s moving very quickly, like a vibrating guitar string, will appear to bend as it moves. The string was in one position for the first stripe of the sensor, but it moved slightly before the sample was taken from the next stripe of sensor. If you do this quickly and repeatedly, the string appears to vibrate in a wave pattern.
Your eyes are constantly taking in light across your whole field of view. Cameras only record a certain number of frames of imagery at a time. Many cameras, such as the one filming this video, don’t even record the entire frame at once: they record one line of a frame at a time, which is called a [rolling shutter](https://en.wikipedia.org/wiki/Rolling_shutter). As you can see in that page, this can cause distortions if the thing being recorded is moving very quickly compared to the speed of the shutter. In the case of your video, the strings are moving back and forth so fast that even in a single frame they’re recorded at being in different spots. In some parts of the frame, a string is recorded at being on the left, and in some parts they’re recorded as being on the right, which makes the string look like it’s bending back and forth dramatically. But the string never actually bends like that in reality, it’s just a distortion caused by recording different parts of the string at different parts in time.
It’s also worth adding that the thinner strings appear to bend more because they are vibrating with a higher frequency
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