Is This A U F O ?

[wolf63]

I saw this on Facebook and it looked strange so I thought that I would share. It seems that this whirly bird is whirling very much at all.

[nailit]

Very odd. Photo shop??

[Quizproquo]

The frame rate of the camera matches the rotors. So if the camera is running at 540 frames per second and the rotor are turning at 540 revolutions per second, this is the result. The camera efectively takes lots of snapshots of the rotors in the same position.
Cool though isn't it.

[wolf63]

I don't think that it is photo-shopped - seemingly all to do with rotor speeds and shutter speeds.

[wolf63]

Quiz - it is strange to watch and it only goes to show that we don't 'see' everything that happens out there in the big bad world.

[Quizproquo]

It is odd to watch, I agree. In a strangely beautiful way though.

[Baldric]

The Helicopter blades are synced with the camera frame rate

[nailit]

//The Helicopter blades are synced with the camera frame rate//
Don't know much about this kind of stuff but then why isn't the boat in the background going much faster and the waves much more 'choppy'?

[Quizproquo]

Because they are not synching Nailit so just appear as normal film, as the helicopter would if it wasn't synching

[nailit]

//Because they are not synching Nailit//
Baldric just said that they WERE synching.

[Baldric]

FUNNY Camera Shutter Speed Matches Helicopter's Rotor Frequency - Agusta Westland

[nailit]

Why are the back rotors different from the front rotors?
Just curious.

[Quizproquo]

Nailit I'm not trying to trick you. Please read my first answer. The rotor blades are synching but the other things in the film are not, so they appear normal. They would only appear different as well if they were doing a similar thing. So if the waves were moving at exactly 270 frames per second, all of them, all at once, they would appear more choppy because they would be at precisely half the camera's framerate, so it would appear a little like stop motion.

[Baldric]

See if this helps

https://petapixel.com/2017/03/04/cameras-frame-rate-synced-helicopters-rotor/

[EDDIE51]

If you keep watching the video to the end the next video up explains it all. Just keep watching!
The roter is rotating (obviously) so the the blades will be in the same position at some point it every rotation.So if the camera frame (picture taking) rate is the same as the rotation rate every picture (frame) will show the blades in the same position. The boat is moving forward it does not keep coming back to the same position, so that will never 'sync' no matter what the camera's frame rate is.
You used to get a similar effect on old cowboy films where the stagecoach wheels looked as if they were going backwards. Again that was just a 'sync' effect between the rotation of the wheels and the frame rate of the camera.

[Quizproquo]

Nice explanation Eddie :)

[nailit]

All very interesting.

[EDDIE51]

Nalit the rear rotor is turning at a different speed from the main rotor so it will not sync. ( or at least not sync at the same camera speed)