Why Do Car Wheels Appear to Spin Backwards in Movies?


As an optometrist, I get asked a lot of questions about the science hidden in plain sight. People are curious about the world around them and why they see things the way they do and to be honest, so am I! I am passionate about learning all I can about the eyes and brain and out of this yearning for learning my blog, "Science Hidden in Plain Sight" and eventually my "Vision Tip of the Week" were born. I am now happy to be sharing my vision tips with you here on Huffington Post Sci.

This week's tip is on car wheels in movies! Ever notice how they sometimes seemingly spin backwards? What's up with that? Well, I did a little digging and found that the phenomenon of car wheels appearing to spin backwards in movies is dubbed "The Wagon Wheel Effect." Movie cameras typically capture a series of still images at a rate of 24 frames per second. If they string together a series of images that show the wheel making less than a full 360 degree rotation in each frame (let's say 340 degrees), then the series of images will give the illusion that the wheel is rotating backwards even when it is clearly rolling forward in the film.

That's my spin on it anyway, hope you found it insightful! Stay tuned for more vision tips of the week from me here on Huffington Post Science. There's plenty of science hidden in plain sight left to discover!