pic: Digital cameras do strange things

[Richard Wallace]

Originally Posted by KenWittlief

... theres more going on in this photo than meets the eye.

The only thing going on in the scene was a guy standing in the fairway swinging a golf club. The .jpg file was captured by pointing a digital camera at the guy and pressing the button. After that I cropped out the periphery to get the file size under the CD Media limit. No trickery.

What I'm wondering is how did the digital camera come out with what we see here? Certainly different sections of the image were captured at different times during the (back)swing -- but why? Was the camera trying to compensate for the moving subject? I'm hoping someone out there knows how these thing work.

To get an idea of the timescale: a top golfer (e.g., Tiger Woods) achieves club head speed at impact greater than 150 feet per second. The swing arc is about 10 feet top to bottom, so minimum downswing time would be about 0.07 second. Typical golfers like this guy would swing more slowly, and if the image was captured during his back swing, the elapsed time from lower to upper club position could be as much as 0.5 second -- although there is no advantage to it, average golfers tend to take the club back quicker than that. Like Ken, I'd have expected parts of the .jpg to be a blur, but what you see is what I got.

[KenWittlief]

ok, if you took the photo then you have a real puzzle on your hands, and as an engineer I expect you to do what engineers do and run some tests on that camera

maybe take photos of a white pole moving diagonally across the image plane, maybe one top to bottom, and one left to right.

Maybe the camera has two CCDs (to get higher resolution) and they are not perfectly synchronized?

Maybe there is a bug in the camera firmware that causes it to not read the CCD from top to bottom. Maybe the capture and hold circuit is not working correctly.

Maybe you had the camera in some weird priority mode that kept the arpeture closed down and slowed the effective shutter speed way down.

Inquisitive minds want answers! :^)

[Richard Wallace]

Originally Posted by KenWittlief

ok, if you took the photo then you have a real puzzle on your hands, and as an engineer I expect you to do what engineers do and run some tests on that camera ...

Right now I'm just looking for a few reasonable hypotheses to test. Thanks for providing some.

Since I've never seen a similar effect before, it doesn't seem reasonable to assume the conditions that caused it will be easy to reproduce. In situations like that, my experience has been that some time spent up front designing the experiment will reduce the time spent later repeating tests that fail to reproduce the effect I'm trying to study.