Spinning Fan Optical Illusion

He he, I see Hidden Tiger Illusion, became instantly one of the most popular ones on this site! You people managed to post 274 comments in matter of few days. Cool! Well for today, combining photos and footage from Boing Boing, Youtube and Flickr, I compiled this article with most amazing jet and helicopter rotating blades illusion. I was inspired to write this when I received email from Eric Cole containing really interesting video (which can be found inside this article). Eric wrote:

“This could be some sort of trick with models or computers, but it looks like the shutter speed of the camera matches the rotation speed of the blades perfectly, making a nice optical illusion effect.”

First photo was taken with camera, from the inside of the flying plane. There are propeller blades that appear to be floating, and that appear in a path that is outside the normal path of the propeller. Now on to the second photo. Johnny Vulkan, the artist on Flickr, took the following photo of a Jet propeller. Is it only me, or does it seem to rotate? Look carefully, and try enlarging it to get better effect.

Today’s magic trick is also neat one. It is a video of impossible card dealing. Go check it, after you finished looking at these propellers.



40 Replies to “Spinning Fan Optical Illusion”

  1. You guys are not the brightest bulbs….it’s the same type of illusion as the spokes or rims of a car. The blades are spinning at just the right speed that each frame of the video captures the blades at nearly the same rotation.

  2. i liked the middle picture best. the top one doesn’t make any sense and the video looks fake!
    But cool ‘rotating’ pic! it seemed to spin more when it was smaller.

  3. there is no way thats real…when the helicopter begins to lift towards the end, the blade is spinning faster so we would at least see the blade move instead of being still the whole time. If the shutter speed was set to that of the blade when it just hovered, then it would not have the same effect when the blade begins to speed up

  4. Okay, so the only reason the copter looks like it’s floating is b/c the shutter speed of the camera is the same as the speed of the propellar. That said, the video looks really great and whoever made it did a good job. I like it.

  5. How can you think it´s fake!?! Naturally the rotation of the blades is perfectly syncronized with the frame frequency of the camera!! Haven´t you ever seen car tyres on a video going backwards?? It´s kinda the same effect…

  6. it’s real, the shutter speed on the camera is the same as the spin of the propellers….

    laymans terms, every frame on the video was taken as the helicopter blades turned exactly once.

    Cleverly done tho!

  7. Hmm, the helicopter thing doesn’t make any sense. Doing those maneuvers, the rotor speed would be varying, and not constsistently sync’d with the shutter speed. I say fake.

  8. nOT EVERYTHING ISFAKE, some of you just are so stupid that you can’t believe anything. why don’t you get off the computer and go experience things in life. or maybe thats just fake to…..cock and balls

  9. I think the helicopter illusion is real. It’s the frame capture. For an example, on tv news- you’ll notice that the computer monitor screen is out of sync due to frame capture by camera.

    If you adjust the camera to right frame speed to match the speed of helicopter rotors, you may see the helicopter as if it “floats”.

  10. The first photo is taken with a digital camera. These proces the info on their sensors line by lines (a bit like a TV works). If the subject moves fast enough, like it does here, it is captured several times as the image on the sensor is processed. hence the result.

  11. That video was pretty cool. I doubt it was fake as you can see the blades rotate relative to the alignment of the helicopter as the helicopter as it does different moves implying the blades and camera shutter move slightly out of phase, which is what a lot of commentors argue is missing for it to be real…

    Also thanks to the anonymous person who explained the propellers, I didn’t understand that one at all.

  12. its not fake… a helicopter’s rotor speed will be constant while doing manuevers like that. Instead of the propellers picking up speed to gain altitude, the angle of attack of the blades increases and decreases to give it more or less lift.

  13. I can’t see the video, but I gather you are talking about a rotor that appears still on a helicopter during flight. Just an FYI; once a helicopters rotor is up to speed it varies very little, a pilot adjusts blade pitch and rotor tilt to move the vehicle. It is therefore very possible for the blades to be synched up with shutter speed (frame rate) during maneuvers.

  14. This is actually very simple. the choppers rotors ARE moving. they just move at the same speed ast the cameras fps (frames per second). So this looks like the blades are not moving but they are.
    This also happens frequently with the human eye, because the eye only registers vision at like 36 fps (i think, i could be wrong on this nuber). So the same type of thing happens.

  15. I think you would have to have an incredible shutter speed to pull that off. But if you did and you got it just right it could work. The speed of the rotor does not have to change to pull those maneuvers. A chopper can gain the lift 2 ways. Change rotor speed (did not happen here) or change rotor PITCH. The rotors on that chopper can change the angle at which they hit the air. This is how they are able to have the rotor spinning at full speed and never leave the ground. Alter the pitch just a little and bam… They are gone.

  16. I couldn’t tell whether it’s fake or not, but i agree on that during these manouvers the rpm rate would have to change due to the quite significant change of the g force. it’s like banking an aircraft makes the rpm drop due to increased g-forces. a pilot can compensate for that it would sure take at least some time to adjust. an autopilot would do the same, probably faster, but definitely wouldn’t keep the rpm perfectly constant like this video implies.

  17. Dude, it’s so obvious, the blades are oriented to spin at the exact speed, in FPS (Frames Per Second) that the camera records

  18. The helicopter is true, the camera can’t pick up the fast blades, i get the same thing after flying for a few hours, you can see the blades spinning and they look like that.

  19. haha its kinda obvious that it’s a toy plane with a string attached to it. the sky is just a painting or a photograph, and the sound was probably taken from a different video

  20. Maybe you are the guy who could answer this. Why, in shots of jet engine exhausts, specifically the SR-71’s, does it look like multiple ignitions in the exhaust trail, rather than one long continuous flame. It is quite unique and I have wondered if it is an optical illusion or something else. I don’t know any aeronautical engineers to ask.

  21. i think it may be real, if you look closly at the blades you can see they do in fact move, not very much but it gves the impression that it is just to fast for the camera to pick up

  22. I think the helicopter’s just a toy hanging in front of the camera while there was a real helicopter passing to create the sound. Or the sound was editted, which is also an option. Still quite a good one.

  23. Oh fer cryin out loud. Some of you got it, most did not. The camera is shooting at the same rate at which the blades are spinning. They DON’T go faster at all – they change their pitch and angle of attack – the spin rate is constant, thus the illusion that they are not moving.

  24. Before you call this fake, learn how a helicopter works!
    They do not change rotorspeed at all!
    When the pilot pulls the collective lever to gain more lift, the only thing that happens is he increases the angle of attack on the rotorblades. The rotorspeed however is constant!
    This video can perfectly well be real!

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