Why do weels seam to turn in the opposite direction in movies?

Landman

It's because the camera can only shoot so many frames per second. The wheel is often moving faster than the camera can capture. It would be like watching the second hand on a clock tick and when the hand reaches the 12 you turn off the lights for 55 seconds. When you turn the lights on after 55 seconds the hand would be at the 11 which to your brain would seem like the hand moved backwards. It's like that but much MUCH faster!

John H

Films are usually shot at the rate of 25 frames per second. Often you see wheels of cars or especially spoked wagon wheels looking like they are going backwards. This is because at the right speed the wheel advances to a point where the spokes are in a different position and this may appear to behind the point where the eyes and the brain think it should be.

If you notice, like in a western, when the stage coach slows down, the wheels look like they are going forwards again. It's just a phenomenon of the photography.

Magaletso

Because the frame rate on the camera is close to the rpm of the wheel, kinda like using a timing light on a car motor to make the flywheel appear to be stationary.

grumpy0282

well its not only in movies, if the wheel is turning at a certian speed it will seem as though its turning at a different speed. i have seen it where it looks like its stopped, going bakwards or turning forwards but more slowly than it actually is. i dont know why it does this, it could have something to do with the way light reflects off it, but whatever it is, its not only in movies

darpunzel

It's just an illusion. The hubcaps and the like make it seem that way. A really neat thing is to have a ceiling fan on in the dark and a strobe light. As you adjust the speed of the strobe light, you can make it look like the fan is holding still, ticking like a clock, or moving in the opposite direction.

pater47

In movies photo frames are moving at a high speed. Sometimes this creates an optical illusion if the speed of the frames and the spokes of the wheel "click". Sometimes you can imitate this yourself by looking at a fan (that's on - DOH!) and blinking rapidly.

A phenomenon that's similar is fluorescent lights. They are not constantly on, but actually blinking on and off hundreds of times a second. Fluorescent lights are outlawed in some factories with high speed equipment because it gives the optical illusion that the equipment isn't on, resulting in missing fingers, feet, heads, etc.

edna b

maybe the ones in the movies are spelled 'wheels'

Claude

It's an optical illusion that's created by the fact that a movie is a series of still pictures being flashed up on the screen. The motion you see is created by something called "persistence of vision", which means that as the first picture disappears, your eye retains it until the next one appears.

Picture a pen dropping to the floor. Let's say it takes a full second for the pen to fall. In a movie, there are a bunch of still images of the pen, from the hand to the floor about 24 frames later. Because the pen goes from place to place, the APPARENT motion of the pen is downward each time.

Because the wheels usually have a pattern that goes all the way around, the wheel will complete only part of its turn from one frame to the next. Because the wheel, relative to the frame of the picture, isn't moving, the lens captures instead the wheel in different stages of the turn. ("strobe" effect.) As a result, when the wheel is turning at certain speeds, its APPARENT motion will be backwards.

If you watch some movies, you'll see a spinning wheel slow down to a stop. It may go through a couple of cycles of appearing to go forward, then backward, then forward again as it slows down to the point where you can see the individual elements turning.

tercir2006

It's an effect called strobing.

Because film is exposed at a set rate, and for instance, the wagon wheels appear to be going backward is because when the first spoke in the first frame moves between the first and second frames, by the time the second frame clicks off, the spoke has moved nearly to the position of the second spoke. BUT, not all the way to that position. So in the second frame it appears slightly behind the second spoke, and the same with the third frame and fourth and so on and so on.

So you are actually watching the wheel go forward but it appears to be going backward because the spoke just doesn't get there before the camera takes another picture.

Moving pictures are simply a series of still pictures flashed really fast (about 30 frames or pictures per second). Here's an interesting experiment you can try with a fan and a standard TV. (flat panel, plasma and the likes might not work) Put the fan in front of the TV and turn them both on. Change the speed of the fan, and you will see the blade appear to be going in the wrong direction. It all has to do with strobing light.

loverboy

movies come from CA, which is backwards state.
everything moves backwards, including the politics.

krispbug

i have noticed that too! but no they are not really moving in the wrong direction, sometimes its the rims on the car that look like they are going backwards. but no they are not. look around at other cars in your area and you will see the same thing.

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