GimliGlider From Germany, joined Jun 2006, 88 posts, RR: 0 Reply 1, posted (10 months 13 hours ago) and read 16288 times:
I believe this is just the result of the way a number of (usually) cell phone cameras take pictures. They scan from side to side or top to bottom instead of exposing all at once. You can see the same effect in some old film pictures of running props.
"You could attach that to your house and still go 0-60 in 5 seconds..."
MrSkyGuy From United States, joined Aug 2008, 160 posts, RR: 0 Reply 2, posted (10 months 13 hours ago) and read 16275 times:
Actually no, it's a common sight from inside the aircraft when taken with a digital camera. I took a similar photo out of the left side of a SkyWest EMB-120 last year and got a very similar prop-flex illusion as well.
Not a fake. A most unusual phenomenon yes, but also authentic.
Honk your horn if you love the old hardware! (707, 727, 732, etc)
ANITIX87 From Switzerland, joined Mar 2005, 2541 posts, RR: 16 Reply 9, posted (10 months 13 hours ago) and read 16063 times:
This is crazy! Everyone says it's real and that it's the result of digital camera, and OOSLC showed proof, but WHY does it happen?? And what settings would I need to try and replicate it? There's a lot of props coming into ABE where I am, and it would be cool to get this type of image of one as it goes by me.
MrSkyGuy From United States, joined Aug 2008, 160 posts, RR: 0 Reply 10, posted (10 months 13 hours ago) and read 16050 times:
Quoting ANITIX87 (Reply 9): his is crazy! Everyone says it's real and that it's the result of digital camera, and OOSLC showed proof, but WHY does it happen?? And what settings would I need to try and replicate it? There's a lot of props coming into ABE where I am, and it would be cool to get this type of image of one as it goes by me.
First, you'll need to be very close to the prop (which is why its most common from inside the cabin). Second, you'll need a cheap digital camera which takes side to side or top-bottom scan photos (like a camera phone) to capture the illusion.
I don't know what settings you'd need to make on your DSLR to capture this effect (or if it's even possible on such sophisticated equipment).
Honk your horn if you love the old hardware! (707, 727, 732, etc)
Here is an interesting view of the ATR prop taken on takeoff with a digital camera. The prop appears to spin one direction then reverse completely and then come to a stop.
JRadier From Netherlands, joined Sep 2004, 3910 posts, RR: 54 Reply 14, posted (10 months 12 hours ago) and read 15870 times:
Quoting MrSkyGuy (Reply 10):
I don't know what settings you'd need to make on your DSLR to capture this effect (or if it's even possible on such sophisticated equipment).
It is not.
For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and ther
EMBQA From United States, joined Oct 2003, 8358 posts, RR: 18 Reply 15, posted (10 months 12 hours ago) and read 15847 times:
No camera expert but... has has to do with the frames per second of the camera and the rpms of the prop and the phase of the two.... Anyone that watches NASCAR will remember when Goodyear went to yellow lettering on the tires a few years back..? That is why. Yellow for some reason photographs better in these conditions. I guess it also has to do with the color spectrum.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
Looking at the ATR photo, this would happen if the camera scanned left to right and the prop rotated anticlockwise, as seen.
I'll try and explain without pictures.
Considering the leftmost blade, as seen, after the first vertical scan is taken by the camera, the prop rotates anticlockwise slightly, so by the time the next scan is taken the prop has moved down a bit and, after successve scans, the blade has moved down a lot. So in the time it takes the camera to scan the distance from the blade tip pointing "north west" to the hub the propeller has rotated so the blade root is pointing "south west." This is what makes the blade appear curved.
Now, because the camera is scanning in the same direction as the blade is moving under the wing, and probably at the same rate, it seems that there is no blade because there was no blade in line with the bit of the image being scanned.
The mysterious 5th blade on the right appears because, as above, the blade is rotating in the same direction as the scanning until the blade is pointing "east" when it starts to go in the opposite direction and then part of the blade is in line with the scanned part of the image.
This reminds me of a tv program about some strange flying creatures that were observed on video and people were convinced that these were new animals when in fact it was a video scanning issue; in the time the video frame had scanned, the animal, a flying insect, had moved and its wing tips had traced out a wavy shape. The animals looked, on video, like some sort of flying tube with long wavy wings along the side.
Man City p3 w3 d0 l0 f4 a0 P9 - hey it may never happen again!
Flyboy2001 From Canada, joined May 2005, 167 posts, RR: 0 Reply 23, posted (10 months 8 hours ago) and read 14529 times:
Ok, from a photographer's perspective, I've done this with both film and digital SLRs. When I take a photo of a propeller blade, my shutter is open for a certain amount of time... I'll arbitrarily use a shutter speed of 1/250th of a second here. During this time, the prop's tip is traveling faster and moving a greater distance than at the hub, so it will actually trace a larger piece of the circle than the rest of the prop... result? An apparently bent propeller on an in-flight aircraft. Add to this the funky ways cell phone cameras scan images and you can have some fun!
Quoting Mirrodie (Reply 18): Though I am surpised no one mentioned the Flexible Rubber Propeller Program that they experimented with. Fortunately, it never took off.
You took the words right out of my mouth! Or maybe the prop blades needed that new additive "Fly-agra"!
Bartonsayswhat From Canada, joined Oct 2007, 373 posts, RR: 0 Reply 24, posted (10 months 4 hours ago) and read 11441 times:
good comments by everyone. just reading some of the coments on the youtube videos makes me thankful for us being civilized. even though every seccond discussion is about DC-9s or AF's dirty planes, we atleast do it civilized
Timz From United States, joined Sep 1999, 5350 posts, RR: 6 Reply 25, posted (10 months 4 hours ago) and read 11217 times:
Quoting Flyboy2001 (Reply 23): During this time, the prop's tip is traveling faster and moving a greater distance than at the hub, so it will actually trace a larger piece of the circle than the rest of the prop... result? An apparently bent propeller
The props angular velocity is of course constant along its length. A pic exposed with a leaf shutter will show a prop blade blurred over a sector of a circle, but no bend, unless the prop really is bent.
26 Soon7x7: Only on a/net can you see something like this...I never even knew this effect existed!
27 Flanker: this is not a fake picture. i have taken pictures like this on regular Cessna while flying. happens all the time.
28 FLY2HMO: Here's another interesting illusion: http://it.youtube.com/watch?v=EDTRMauSHSo
29 Aer Lingus: You're spot on! Correct, this is why I don't like taking pics of props. Its difficult to get things right. Either the props blades are frozen or ther
30 MEA-707: very interesting bended prop blades effect of an Il-18, see http://ca.youtube.com/watch?v=dv5gvKaAoYk&feature=related
31 Lemmy: You can see the same effect in finish-line photo systems, which pass a length of film across a slit. So the horizontal axis of the film is read as tim
32 DocLightning: http://www.youtube.com/watch?v=vlZvBIgTE68&feature=related This illustrates the effect here much better.
33 Spacecadet: The iPhone does some interesting things to propellers: http://www.flickr.com/photos/geog/2343283410/ Even the shadows! http://www.flickr.com/photos/am
34 SpeedBirdA380: Is there anyone that can explain why this happens? Its a GE-90 starting up and the fan blades seem to be changing direction and coming to a stop throu
35 Spacecadet: That's simpler to explain - the frequency of the blades turning is initially slower than the frame rate of the camera. At a certain point it matches
36 NA: Funny effect, I never noticed that. I have to check my pictures of Props, oddly I cant remember to have seen it on thousands of pics before.
37 SpeedBirdA380: [quote=Spacecadet Reply 35[/quote] Thanks very much for the explanation.
38 Brilondon: If i see this out of the window it is probably because of the liquor cart.
39 Lemmy: It's pretty simple, actually. Take a look at the bike race picture I posted above. Since the film is being passed behind a vertical slit, each point
40 Spacecadet: I'm gonna need some kind of diagram or something. I went to film school but I can't get my head around this. I think the way your finish line system
41 MrSkyGuy: You won't unless you are using a relatively low quality side-to-side or top-to-bottom/bottom-to-top digital camera like the camera built in to your c
42 Mandala499: Here's more... The side that has the least number of props is moving in the direction of the "linescan"... Photos not taken by me... As you can see fr
43 Oly720man: It's not a frame, it's a vertical slice of a frame. To demonstrate the effect with a propeller.... Have you got a reasonably sized clock with a secon
44 PHKLM: RR for this brilliance piece of entertainment!
45 Spacecadet: Yes, I understand that. What this doesn't explain is why this doesn't happen to all the propeller blades equally. In other words, all the blades are
46 Timz: You've confused two different meanings of "in the same direction". An object moving in a circle isn't actually moving in the same direction.
47 Tdscanuck: Because the camera is scanning in a straight line (either veritcal or horizontal), while the prop is going in a circle. The camera only "sees" the ve
48 Pilotboi: They are spinning the same direction yes, but they are not FACING the same direction. Some are up, some are down, some are left, some are right, etc.
49 AAmd11: Q400, shot taken by me with my LG mobile phone with 3.2 mpix camera. The camera doesn't like high speed spinning, really.
50 Timz: Say you're photographing a second hand on a clockface with a camera that takes exactly 30 seconds to scan the diameter of the clock, at a uniform spee
51 Pilotboi: While explaining this to a friend, he reminded me of a perfect example! (For those who still don't get it) The cameras that take these pictures are si
52 Rwessel: Actually that's not true. A typical film shutter has two curtains, and the move across the frame at a fair clip, but staggered a certain amount in ti
53 TFFIP: Maybe my mother in law isnt so bad after all. I should visit one time in a while and stop just waiting to see the photos when mrs. come home from a vi
Sponsor Message: 
From Venezuela, joined Aug 2004, 2460 posts, 
From Germany, joined Jun 2006, 88 posts, 
From United States, joined Aug 2008, 160 posts, 
From Spain, joined Jun 2007, 430 posts, 
From Belgium, joined Jul 2006, 1114 posts, 
From Switzerland, joined Mar 2005, 2541 posts, 
From Austria, joined Mar 2007, 393 posts, 
From Netherlands, joined Sep 2004, 3910 posts, 
From Canada, joined Aug 2007, 2060 posts, 
From Turkey, joined Jun 2007, 105 posts, 
From United Kingdom, joined May 2004, 4741 posts, 
Printer friendly format 
