Jan 21, 2009: Digital Weird

[Gravdigr]

Originally Posted by Wombat

Nose cones don't cover the propeller blades. The blades come out the side of the nose cone. Which makes the photo plausibly real, not photoshopped.

Here are some pics of stationary propellers so you can see how the blades come out the side of the nose cone:

So it (the camera)manufactured parts of the prop that don't even exist?

[Wombat]

Originally Posted by Gravdigr

So it (the camera)manufactured parts of the prop that don't even exist?

I can't see any parts of the prop that don't exist, so I'm not sure what you are referring to. To me, every part of the picture looks consistent with a focal-plane shutter exposure of a moving object. Yes it is weird, but I think it's genuine

[xoxoxoBruce]

But how do you get a continuous blade, with two red tips, and no red nose cone in the middle?

[Razzmatazz13]

Originally Posted by Sundae Girl

Ooh, ooh! I want one of those, do you know where they sell them?

Actually...the last time I was camera shopping, they had cameras that claim to fix blotches on your face automatically (after auto finding your face in the frame of course) and other such craziness.

This one makes you skinnier:
http://www.reginalewis.com/2007/09/1...ounds-thinner/

[barefoot serpent]

lots more examples here and discussions of photon gating and Nyquist frequencies etc.

[barefoot serpent]

another example

[spudcon]

Moving objects in the same speed/direction as the scanner on a copy machine makes the object look longer. :-)

[Wombat]

Originally Posted by xoxoxoBruce

But how do you get a continuous blade, with two red tips, and no red nose cone in the middle?

Good question, lets see if we can work it out.

Looking at the pitch of the blades at the top-center of the picture (where there is least distortion), I think the propeller must be spinning clockwise as we look at it. That way the blades are pushing air towards the back of the plane.

If the shutter is a vertical slit that moves from right to left as we look at the picture, I think that explains the effect we see....

In the top-center of the picture, the blades and shutter pass in opposite directions when both are close to vertical, so we see straightish blades.

On the right of the picture, the tip of the blade passes the shutter first, then as the blade swings down through horizontal the shutter has moved slightly further left so we see the middle of the blade slightly further left than we saw the tip, and finally as the blade approaches the bottom of its swing the fast-moving blade tip overtakes the slower-moving shutter, and so we see the tip again slightly further to the left. The result: it looks like a double-tipped blade floating unattached in the air

I'll let you figure out what's happening on the left of the picture yourself

[HungLikeJesus]

I agree. If the shutter is moving left to right, the propeller has to be spinning clockwise (from our POV). Because you can see the root of the propeller in the top but not the bottom, the smallest relative velocity between the shutter and propeller must occur there - so they're moving in the same direction at the top and the opposite direction at the bottom.

[Elspode]

But...if the plane was on a treadmill, and the iPhone was trying to take off, would the propeller blades appear at all?

[Griff]

Depends. Is the treadmill on a train approaching the speed of light?

[SPUCK]

No! But the train did leave the station going west.

[Gravdigr]

Originally Posted by Wombat

I can't see any parts of the prop that don't exist, so I'm not sure what you are referring to. To me, every part of the picture looks consistent with a focal-plane shutter exposure of a moving object. Yes it is weird, but I think it's genuine

I was talking more or less about the part of the prop that bolts to the hub. Where do the hub flanges disappear to, and where does the section of prop that magically appears to connect two seperate sections of prop where there should be hub flanges (for lack of the correct term) appear from?

And, to clarify, I'm not saying the pix are actually photoshopped. (I just thought the bs flag was cool) Just perpetuating the oft repeated cellar mantra. I've seen these type pix before, I just can't wrap my fragile little mind around the idea.

[Anon. Y. Mouse]

I believe you're seeing the reflection of the blades on the nose.

[lumberjim]

Anon E Mouse would have worked better


eta.....unless your 1st language es Espanol