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Propeller iPhone Effect
Posted 13 years ago by retro in category: misc
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- 13 years ago [ Reply ]
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The hell's happening? Some form of aliasing?

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Mystery - 13 years ago
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  http://en.wikipedia.org/wiki/Stroboscope Essentially it is just the camera taking a picture (a frame) when the prop is at the same stage in the spin. Most likely the pilot set the prop RPM to be in sync with the camera's FPS  

HoraceSPatoot - 13 years ago [ Reply ]
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There's a second phenomenon. The raster graphics scans vertically and right to left, so the propeller has advanced slightly as it gets to the left side of the photo in the scanning compared to where it was at the beginning of the scan. This explains why the prop appears to flop (I like how that sounds). The pilot didn't have to do anything very special with the engine speed. The propeller will appear to stop every time the revolution rate is an integer multiple of the camera scan rate, and whenever it's close to that the prop appears to turn slowly.

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LW (guest) - 12 years ago [ Reply ]
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this video was hi-jacked from here: http://laurawaller.com/index_files/iPhoneAliasing.htm The pilot isn't doing anything special, just telling you RPM so you can figure out fps.

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