There are two different effects here. One, as in the iPhone and all similar devices, is a scanning phenomenon caused by the fact that cheap or very small senso

There are two different effects here. One, as in the iPhone and all similar devices, is a scanning phenomenon caused by the fact that cheap or very small sensors are usually CCDs. Since such cameras do not actually have real shutters, the equivalent effect of a shutter is achieved by delaying the time that each line is exposed and read. Because cheap CCDs do not have multiple channels, the lines are read one at a time in sequence. The maximum speed that the lines may be read sequentially is the maximum "shutter speed" of the camera. The other is the traditional curtain shutter of an SLR. Even a high-end CMOS multi-channel sensor will still see a slit of light on any speed upwards of 250, even though the data is not necessarily read a line at a time. Thus, whereas the sensor in an SLR is exposed via a slit of light at higher shutter speeds, cheaper non-SLR cameras are always exposed one line at a time. Thus this effect is more likely to be seen on a camera phone than on an SLR.