sometimes when I watch a movie ,wagon wheels seem to be spinning backwards. an optical illuision? I ask you?
2006-06-23 17:03:38 · 11 answers · asked by EARL L 1 in Science & Mathematics ➔ Engineering
It's an optical illusion
2006-06-23 17:08:30 · answer #1 · answered by mapleguy 7 · 0⤊ 1⤋
Good answers all but a little more depth-Have you ever noticed a computer screen when it is captured on a video tape? You can see the lines moving up or down like the vertical hold is off. This is also the same for the wagon wheel or any other wheels in motion.
The video monitors seem to have lines because the capture rate of the video is different than the sweep rate of the monitor. It is a strobe effect, like the indicator on some turn tables. The spokes of wagon wheels behave the same way as the film moves at a certain speed, the camera is at a certain shutter speed and the wheels go at their speed. This action is accented by the bright movie lights, which flicker at their speed (the main reason you see a strobe effect). Take a simple normal 20 inch box fan, set it on the floor in front of a TV, turn down the lights, what do you see?
2006-06-23 17:24:44 · answer #2 · answered by orion_1812@yahoo.com 6 · 0⤊ 0⤋
It is indeed an optical illusion resuting from the spokes in the wheel. Our eyes can only process motion at a certain rate. If you imagine a wheel turning at exactly the right speed so that one spoke exactly replaced the position of the one ahead of it, it might seem that the wheel stopped since all the spokes would seem to stay in the same position. Also, if it were moving twice as fast, you would still see the same effect since the spoke would move two positions, but still replace a spoke in the same position. Now imagine it moving slightly more slowly so that the spoke comes up slightly behind the spoke it's going to replace. You would have in effect the same thing as a flip-card cartoon where each of the pictures represents slightly advanced action and when viewed flipping the cards very fast gives the illusion of motion. In this case, the illusion is the impression of the spokes turning slowly backwards.
2006-06-23 17:18:33 · answer #3 · answered by Traveller 3 · 0⤊ 0⤋
Hi there. Doodlebug is correct, any wheel spinning can reach a speed where the eye is deceived - the brain cannot process past certain speeds. It is easier to see in wagon wheels because the wooden spokes give the eye a definite target to focus on. When you see a spoke and the image is processed by the brain, by the time you have formulated the picture the spoke is next visible to you further back - so it looks like it is going backwards, when going forwards at high speed. Cheers, Steve.
2016-03-15 18:31:29 · answer #4 · answered by Anonymous · 0⤊ 0⤋
When those movie's were filmed as with movies of today's time, the camera records at a certain speed, the wheel's turn at a different speed which causes them to appear to be turning backwards
2006-06-23 17:08:32 · answer #5 · answered by kodiakman9000 3 · 0⤊ 0⤋
The same effect is seen with aircraft propellers. It is called the "strobe effect", in motion photography. A similar thing happens when you try to photograph a TV picture. In that case you have to use a shutter speed of 1/30th of a second to get a complete picture. It is due to the relative difference in the "speed" of the two systems. In the first case the wheel or propeller is "strobeing" across the fixed speed of the camera as in the second, the TV picture is strobeing the camera shutter and too fast of a camera speed will result in only a band of a partial TV picture on the film.
2006-06-23 19:46:57 · answer #6 · answered by Dusty 7 · 0⤊ 0⤋
It is called the "wagon-wheel" effect. It is an optical illusion.
Imagine that the wheel has black spokes except for one white one. If it starts pointing straight up (and your eye "captures" the image at that point) and then turns 330 degrees clockwise, and then your eye "captures" the image at that point -- it might seem to you that it had actually turned 30 degrees in the opposite direction. This is called the "strobo-scopic" effect. Sometimes your eye can play this trick on you, but especially when it is on film, because the film is actually "capturing" distinct images.
2006-06-23 17:07:52 · answer #7 · answered by ksjazzguitar 4 · 0⤊ 0⤋
the cameras sucked back then.... the wheels turned almost all the way around by the time the next frame was shot. So each spoke looked like it was moving backwards.
2006-06-30 05:40:03 · answer #8 · answered by Justin P 2 · 0⤊ 0⤋
Yes it is an optical illusion. Its based on the frequency of the light you are viewing them through and the speed (frames per second) of the camera that filming. Mostly, it has to do with light frequency.
2006-06-23 17:12:37 · answer #9 · answered by M4free 1 · 0⤊ 0⤋
it occurs because the rotational frequency of the wheel is a little off from the frequency of the frame capture of the camera used.
2006-06-23 17:09:02 · answer #10 · answered by jollycrapper 2 · 0⤊ 0⤋