pmgoodwin

Okay, this is a little OT but it was taken while driving Porsches at high speed
on a PCA drive.

I had my iPhone out trying to take a pict of a a friend as I passed him. I ended
up getting his front wheel instead. I was about to delete it when I noticed
something strange about the wheel.

The photo below is not photoshoped or doctored in anyway. Can anyone
explain what caused the effect.

Paul

trackjunky

I'll ask Scully.

Regards,

Fox Mulder

007DT

WTF!!! He must be going 88 MPH... Were there Flames behind the rear wheels?

pmgoodwin

We were in the 60s not 80s.

Oh, I just got the reference...

007DT

Mark in Baltimore

My guess is that the effect is due to some sort of shutter issue:

http://cameratoss.blogspot.com/2007/...istortion.html

http://flipthemedia.com/index.php/20...ve-constraint/

Jimbo951

It looks like the camera is scanning from top to bottom.

The top spoke starts toward the rear, and as the camera scans downward, the wheels is turning.

Same thing is happening with the bottom spoke, but in reverse.

pmgoodwin

The spokes and the bolt holes are all distorted but the bade on the cender cap is normal.

A930Rocket

I've had similar pics with moving subjects. I have one where my son moved his head at the last minute. Everything is clear, but his face. I'ts a blur, like it has been swirled.

333pg333

The factory finally designs an interesting wheel?

Jimbo951

Not really. Blow it up and you'll see that the center cap has some smearing.

It's not as drastic because just spining. The top and bottom of the wheel has large left-right velocities.

JC in NY

rolling shutter artifact

ew928

Thought the asymmetric wheel designs went away after the early 80's.

Cool scanning shutter effect. Think the iPhone has electronic shutter.

Van

It has to do with your shutter speed and the fact that the wheel is rotating relative to your (the camera's) movement.

I've seen this when I've taken pictures of cars on the track - the top of the wheel has the spokes distorted. At the top of the wheel, the spokes have extra forward velocity - the speed of the car plus the speed of the rotation of the wheel. The spokes at the bottom wheel have a reduced velocity (speed of car minus speed of wheel rotation).

To put it another way, using my example of taking a picture of a car on the track, from where the photographer stands, the road is not moving - so the road will not be blurry / distorted. As the car drives by, the part of the tire that touches the road is moving forward at the same speed as the road (zero); the center of the wheel is moving forward at the same speed as the car; and the top of the wheel is moving forward faster the speed of the car. If the camera's shutter speed is just right, it can "freeze" the road and the bottom spokes, but the top spokes will be blurry.

I think you're seeing the same effect, but, since you were moving along side your friend the blurry part appeared in the front (maybe you panned or moved the camera up slightly when you took the picture), and you just lucked out with the spoke placement to make the picture just like that.

So, maybe it's a one-in-a-million type of shot!

analogmike

No, it's due to the way the iphone scans from top to bottom as described above.

Put your hand on a flatbed scanner sideways and when it starts, slide your hand away from the scan bar slowly. You will have LONG fingers.