The effect you see is mesmerizing, but not really representative of the way that guitar strings actually oscillate. Instead, it's another example of how the iPhone 4's rolling shutter can create ...

The rolling-shutter camera doesn't capture an entire image all at once. Rather, it captures images line by line. That slight time difference can cause the strange oscillation effect seen in the video.

The Sony A9 III's global shutter has a sensitivity of 250-25,600 (exp.125-51,200). To put that into perspective, Sony cameras traditionally have a base of ISO100.

That "global shutter" can thus eliminate rolling shutter effect, which skews vertical lines on fast-moving objects. All of this is good news for camera fans.