The Wobble Effect – small dead animals

13 Replies to “The Wobble Effect”

I believe this is the same effect that you see in films when the wheels on a car/wagon/etc. look like they are turning slowly in reverse even though the car is moving forward.

A whole new genre – slack key double bass.

It looked as though the strings were loose.

The sampling rate on the digital camera is some multiple of the string’s vibration, I would guess.
You can probably see the same thing when filming a typical liberal: get the shutter speed just right and you can see them physically wobble, right along with their logic.

Is that how Dr. Fruit Fly wabbled out of the radio station?

Is this where the phrase slackers comes from?

My first thought was “rolling shutter”. Not that the camera in question is cheap, but I see so many videos on the web made with cheap video cameras it’s naturally the first thing that comes to mind.
Here’s video from a quality high def camcorder (one I happen to own) demonstrating the effect.

Don’t let G Lonechild see the video, he’ll think he’s DRUNK AGAIN.

Way cool!

Check out the bent propellor on the Nanton Lancaster.

This is aliasing I believe (unless visual CG effects have been employed to make this).
Basically, say a string vibrates at freq X (say 1000 Hz). If you wanted to record this properly, and (capture all the vibrations correctly) you should record it at a sampling rate of a least 2X (i.e. 2000 Hz). Anything less and you would start aliasing.
What happened here is that a video camera was used and normally they having sample rates of what, about 24 or 30 frames per second, i.e. 20 or 30 Hz (I’m not a video cam guy, but this is in the ballpark).
This is much lower that the frequency of the string. So what you are seeing is snapshots of the string taken at different intervals, that when played back make it look like a fluid motion.
In fact, the up/down position of the string ‘captured’ in any single video frame is separated from the string ‘capture’ in the next video frame by a integer number of complete up/down vibrations plus a small delta. If there was no small delta, then the string would appear to be still.
As there is more than one string displaying this behavior, then it would appear that the strings are all harmonics of each other, which I guess is normal for a musical instrument and part of the tuning a musician does at the start ( a musician I am most definitely not).