OK My Fellow Photography experts, what causes THIS?

So some friends, my wife, and I show up to a park a while ago, and lo and behold, the police were running training exercises. It was pretty neat, my friend knew the lead helicopter pilot, and we talked to a bunch of the rescue guys. We had come to the park to go sailing and have some fun, all spur of the moment like, so I did not have my camera.

But, I did have my iPhone. Attached are three of the pictures I took of the helicopter with my iPhone. First off, I'm kind of impressed that the phone has such a fast shutter, I guess I never really thought about that before. So, on to my question. What in the heck is going on with the chopper blades? One of the cops had an iPhone there as well, and his looked exactly the same.

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Maybe this will help...


Blade illusion

Here's another common illusion, the frame rate matches the blade spin rate...


Blade Illusion

oh, well look at that ^^^ there you go!

that seccond link is awesome!

It's cause the guy is really heavy.

Duh.

There is in fact some upward curvature of helicopter blades particularly in hover, as they are carrying a heavy load than in normal flight. Look at a chopper on the ground some time and you will notice there is often droop as well, when the engine is stopped. I would suspect your little phone lens is at it's widest angle, and has some distortion., but then again, I have never managed to 'stop' helicopter blades in flight

Wow, that was quick. First post solved it! I guess I probably should have known that, but.... I didn't

That youtube video is cool!


and KiwiChris, I know the blades curve up a bit, but not THAT much

katodog wrote in post #6886154
Here's another common illusion, the frame rate matches the blade spin rate...

Blade Illusion

Helicopter as a fixed wing aircraft!

As for the 'heavy rescue victim', merely the visual affect of the vertical focal plane shutter blades of the modern dSLR. Analogous affect was known to occur to elongating (American) footballs travelling thru the air with the horizontal cloth focal plane shutters of yesteryear.

katodog wrote in post #6886154
Maybe this will help...

Blade illusion


Here's another common illusion, the frame rate matches the blade spin rate...

Blade Illusion

Hadn't seen that YouTube video before. That was pretty cool. You could actually see the rotor mast moving and the blades changing pitch but the rotation was totally negated.

Did you read the comments on the YouTube video? There are some really lame explanations of the phenomena.

That is so weird, because all of the copters that I have taken photos of, not one has looked like that, thought it was barrel distortion, but looking at the ground, suggests other things are not right with the lens, dunno, just a hypothesis

400dabuser wrote in post #6890925
That is so weird, because all of the copters that I have taken photos of, not one has looked like that, thought it was barrel distortion, but looking at the ground, suggests other things are not right with the lens, dunno, just a hypothesis

Re-read #7

Wilt wrote in post #6890984
Re-read #7

But didn't I say it hasn't happened to me???

http://chdk.setepontos​.com/index.php/topic,2​32.0.html

There was a similar photograph posted in this thread but the poster somehow got pissed for some reason and deleted all his psots from that site.

400dabuser wrote in post #6891012
But didn't I say it hasn't happened to me???

From your earlier reply it sounded that you were still puzzled, although speculating about optical distortion caused by the lens. "I dunno".

True reason is the distortion created by the narrow slit of the shutter moving across the sensor while parts of the helicopter are also in motion, so different parts are recorded when they are not at the same point in space.

Wilt wrote in post #6889579
Helicopter as a fixed wing aircraft!

As for the 'heavy rescue victim', merely the visual affect of the vertical focal plane shutter blades of the modern dSLR. Analogous affect was known to occur to elongating (American) footballs travelling thru the air with the horizontal cloth focal plane shutters of yesteryear.

I didn't know the Iphone was a DSLR?