O/T Bizzare prop arc in digital photo

[AirDOGGe]

How Did An iPhone Take This Picture?

by Casey Chan
cchan@gizmodo.com


How Did An iPhone Take This Picture? Unless the blades of this airplane propeller can defy gravity and float, the iPhone's camera totally distorted reality with this picture. How did this happen? No, it's not Photoshop. It's because of the camera's "rolling shutter".

So 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".

And though the "rolling shutter" is typically fast enough and hardly affects daily life, it means when you're trying to take a picture of an even faster moving object, distortion like the picture above occurs.

[Outer6]

Re: O/T Bizzare prop arc in digital photo

Very cool pic. I took a close up of a helicopter landing using my iPhone and the prop arc was distorted that they looked nearly vertical. I later showed it to the pilot for a laugh. He got a big kick out of it and was very glad the blades didn't bend that much.

[mrcraigarcher]

Re: O/T Bizzare prop arc in digital photo

Mine's not an iPhone, but you get the same effect. This is from my flight in Aluminum Overcast.

[ignomini]

Re: O/T Bizzare prop arc in digital photo

Although this effect is unique to digital imaging (and yours' is a particularly amusing example), "rolling shutter" effects are nothing new in photography. If you look at many photographs of early race cars at speed, you will notice they appear to be leaning forward.

Early focal plane shutters were made from cloth and incorporated horizontal gaps or slits of varying width. The size of the gap, combined with spring tension on the roller, set the shutter speed. A fast moving car would have moved forward during the time it took the gap to travel vertically up the film.

Everything new is old again

[AirDOGGe]

Re: O/T Bizzare prop arc in digital photo

My Canon A1 has a side-to-side shutter curtain, and at least one prop blade would appear curved in my reno flyby shots taken out at the fenceline, while the other 3 blades usually looked normal. I'll have to dig out an example...


Meanwhile, here's another example of weird digital prop illusions:

[boom3]

Re: O/T Bizzare prop arc in digital photo

The nice thing about these rubber props is you don't need an engine tear down after a prop strike.

[Cal Diver]

Re: O/T Bizzare prop arc in digital photo

Here's an IPhone pic my Dad took in an Air Tractor 802