If Seeing Really is Believing… Never Point Your Smartphone’s Camera at an Airplane Propeller

Updated on 25 July 2011 by

If I saw this out the window of a plane, I’d be a little bit terrified:

 

This seemingly horrifying scene is the result of the way that images are captured by the sensors that we find in many modern smartphones.

Unlike real film cameras, active pixel sensors (like those found in many smartphones) don’t expose every pixel at the same time, but rather, do so in sequence. While the consequences of capturing photos this way is trivial for most things, objects moving at high speed may seem to exhibit some strange behaviors, like the propeller above which appears to be literally falling away from the airplane.

This is definitely tough to explain with text alone but you may find this visual explanation helpful. In the video, the line that moves from the top to the bottom represents the sections of the sensor that are actively capturing data:

If seeing really is believing… never point your smartphone camera at a propeller while in an airplane!

1 Comments For This Post

  1. Steve Jerb says:

    Sweat explanation of an important tech-point. i can impress the friends annd the “chaps” at the bar with this one thenks again! This one is worthy of their admiration and will “get them good where it counts.” I appreciete the explanation of the strorboscopic effect now i know when i see what is believd!

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