Since nowadays most photos are taken with smartphones, Rolling Shutter effects have become more present than ever. For those who aren’t familiar with the term: these effects are image artefacts that make lifelike pictures of fast moving objects impossible. The most frequent examples are vertically distorted propeller blades of a plane or diagonally distorted cars. These image artefacts are caused by a non-existent mechanical shutter. For a lack of space, but also for cost reasons smartphones and compact cameras don’t have it. Another aspect is that such devices mostly contain small and cheap sensors which can’t capture the image completely but only one row or column at a time. Picture it like this: the exposure length of single rows or columns of the sensor is equivalent to the shutter speed, but as rows or columns are exposed and read one after another, the exposure of the entire photo clearly lasts much longer. Then the display indicates for instance a shutter speed of 1/1000th of a second, which is certainly correct in regards to single rows/columns, however the entire image is only taken after 1/60th of a second. Some types of electronic shutters are faster (1/120), others are slower (1/30), but this doesn’t change the fundamental problem.
The visual guys among you, who might not know how to interpret my writing, should compare the following GIF with the image linked further above. 😉