http://www.diyphotography.net/everything-you-wanted-to-know-about-rolling-shutter/
Last month's item on using a smartphone in a guitar to display repetitive patterns on the strings in a strobe-like fashion drew a number of email and PHYS-L comments. While I had thought the phenomenon was a simple under-sampled signal producing a temporal alias, “WebSights” readers pointed out that the signal disappeared when the phone was rotated by 90°, and that the effect was also dependent on the distance between the phone and the strings. PHYS-L posters came to the rescue with links to a DIY Photography page discussing rolling shutter distortion by Udi Tirosh. There are several YouTube videos devoted to rolling shutter video distortion, and, given the ubiquity of smartphone cameras with CMOS video sensors, we'd better get used to seeing and interpreting this effect (as well as good old-fashioned temporal aliasing) in mechanics classes. Still a great physics of sound illustration.
Thanks to PHYS-L posters Zeke...
