pic: Digital cameras do strange things

[Richard Wallace]

Originally Posted by David Brinza

Maybe the scan is from bottom up and we're looking at the backswing.

If the picture was taken on the downswing, I'd expect the clubhead to be really blurred just before impact with the ball. (In a good golf swing, max clubhead speed should be just as the club is striking the ball)

Good catch! That's the most reasonable explanation I've heard yet. The golfer's foot positions are also more consistent with a backswing.

[Rosiebotboss]

I'd like to see this try to be duplicated.

Maybe I can conduct some tests during the R^2 Challenge Cup at next week's 5th Annual Tournament of Rosie. <shameless promotion>

Still a few spots left!! see www.team839.com for more information. Or PM me.

[KenWittlief]

a few years back I had my photo taken for my drivers license.

I can only surmize the camera they used scanned your face from left to right, because I was watching someone walking across the room as they took my photo

and it came out with my eyes pointing in different directions, ala Son Of Marty Feldman

thats what was on my drivers license for 4 years!

[Bill_Hancoc]

Originally Posted by David Brinza

Maybe the scan is from bottom up and we're looking at the backswing.

If the picture was taken on the downswing, I'd expect the clubhead to be really blurred just before impact with the ball. (In a good golf swing, max clubhead speed should be just as the club is striking the ball).

I think there are some digital cameras where the entire CCD is "gated" for a fixed exposure time and the readout is done after the exposure. You wouldn't see the effect observed in photo - the club would only appear in one portion of the swing, perhaps blurred.

Agree because if you look at the direction of the club is curved it looks like the club stayed put while he swung back

[KenWittlief]

there is one aspect of the picture that leads me to think it has been photoshopped to some degree

if the club is captured in different parts of the swing, then why is there no blur in his hands, esp the white glove?

How did he move the club without moving his hands?

something else I just noticed, there is a discontinuity in the club -the upper club does not connect to the 'lower club'

It looks somewhat like strobe light photos with an unsynchronized shutter plane (maybe not really a digital photo?) It looks like the man was shot in the dark with maybe two flashes, and then superimposed onto a photo of the golf course?

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

[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! :^)

[Alex Cormier]

reminds me of this picture i took at FLR this year.

[sanddrag]

Some family friends once took a digital picture and it came out weird like this. The camera was set on a table, the timer was set, and then the guy who set the timer ran in to join the group shot. He made it in well before the timer expired and the shot was taken. However, when the picture was viewed, he was transparent (and only him too). I could see the fireplace in detail right behind him even though he was standing in front of it and nothing in the picture was blurred indicating he was moving quickly as the shutter closed. Everything was crystal clear, but he was transparent. It was very strange.

[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.

[KenWittlief]

Originally Posted by sanddrag

...Everything was crystal clear, but he was transparent. It was very strange.

Ive seen a similar effect on older digital cameras when a flash is used indoors.

They were not very good about choosing between long exposure times and triggering the flash, so sometimes it would do both, leaving the shutter open for a good part of a second, then firing the flash as well. This would explain the long exposure catching the fireplace, then the flash catching the person infront of it, making him transparent.

Richard, since digital photos are free one experiment you might try: take a black computer fan and paint a straight white line on one blade, or all the way across from blade tip to blade tip.

If you power the fan with an adjustable DC supply you should be able to vary its speed, and take some test shots (or you could give it a spin with your finger)