Videos Reveal Guitar String Movement

This story begins not with how guitar strings actually vibrate, but a curious phenomenon when combining the regular oscillation of the string with the rolling shutter of a CMOS digital camera — namely, the iPhone’s. To accurately capture motion, you need to record an image all at once (or at least come close). Rolling shutter or line scan as exhibited in a CMOS camera sensor like the iPhone is a side effect of the capture being scanned from top to bottom, so the bottom portion of the image is saved later than the top. That causes motion to skew across the image. (Long before digital, people played around with the same effect in analog video and even using film photography – all you need is something moving and a way of capturing the image that moves gradually in a different direction.)