Gizmodo has an interesting article about how the iPhone (and probably other digital cameras) can distort fast-moving objects, with propellers being the most common example. This iPhone video of a propeller is from the comments; there are lots of other examples in the article. Weird effects happen because "as it turns out, most digital cameras don't actually take a picture the instant you hit the button. What they actually do to capture an image is scan over the frame either vertically or horizontally. So basically, not all parts of an image are recorded at exactly same time (the top right could be a little ahead of the bottom left, etc.). Hence it being called rolling shutter."


It is cool to think that if our eyes had rolling shutters, this is how we might see the world too, with fast moving objects seeming to move in and out of existence or bend in strange ways. It's a great example of how perception is not necessarily reality.