Where's the propeller?

[Dreamster]

Here is an interesting picture. The lines represent my digital cameras interpretation of the propeller.

Somewhere between Las Vegas, NV and Laramy, WY.

[Mike S]

This has been discussed here before.

Here is a link to info on the effect.

http://en.wikipedia.org/wiki/Anti-aliasing

[asav8tor]

I've been flying for 30 years. Regardless of whether it was a T-38 that weighed over 12,000 lbs and could go supersonic with just 2 small intake holes; A B-52 that could lift almost a half a million pounds off the ground; A HH-60 BackHawk with floppy blades spinning over my head; or my RV with that little toy propellor up front; I always knew it was a trick with smoke and mirrors. No way any of that stuff could really fly. Air is too thin. Just a trick. Something else going on. That's what the camera caught, the secret force. I knew it the whole time.

[Pirkka]

Originally Posted by Mike S

Here is a link to info on the effect.
http://en.wikipedia.org/wiki/Anti-aliasing

Anti-aliasing?! I guess you mixed things now... anti-aliasing (as you can read from your link) is more like "making color transitions softer".

[PCHunt]

I tried to read the Wikipedia page on anti-aliasing, I really did. Read it three times, in fact............. Then I poured a couple of really STIFF bourbons, and tried again.

Still couldn't understand it! But the pictures were prettier!!!!

[Mike S]

Try this one then, also try following the link on "Wagon wheel effect"

http://en.wikipedia.org/wiki/Temporal_aliasing

Digital cameras dont take a picture all at once, they scan side to side, line by line until they have taken thousands of small individual clips of the whole.

What is happening is the camera is getting a small part of the prop, and then the next clip/exposure a millisecond later gets another shot of the prop, but in a slightly different location.

Because the exposure stops and starts, the moving prop ends up being a line, that represents the props location at the time the clip was taken.

In a film camera, this would come out as a blur, but the multiple tiny exposures of the digital dont catch the motion as a blur.

[Tram]

If you that picture is nuts..

Here's a good lil' video..

http://www.filecabi.net/video/ufochopper.html

[kentb]

Originally Posted by Tram

If you that picture is nuts..

Here's a good lil' video..

http://www.filecabi.net/video/ufochopper.html

I wonder if it just work out that way or did they adjust the frame rate on the camera to match the rotors RPM.

Kent

[verrice]

That's certainly interesting... not anti-aliasing or wagon wheel though. I don't know about other cameras, but both of mine expose all 'pixels' of the sensor at the same time. An NTSC video camera would be different as it only does half the lines at a time, but a still should just open the shutter, get light, and close.

I've used two different digital cameras with planes, a Nikon D70s (DSLR) and a Canon SD450 (pocket point and shoot), and never got anything like that. Always a true motion blur, like one would expect.

What make and model camera was that taken with?

[Tram]

Originally Posted by verrice

What make and model camera was that taken with?

I could tell you but, then I'd have to kill you..

I have no idea..