2 Little balls.....

[R1Geezer]

Watching cricket the other day and when a boundry was hit the camera follows the ball, I noticed that there was a little ball either side of the actual ball on the TV screen, Obviously some optical effect caused by the camera. Can anyone explain this phenomenon, It sometimes happens in Golf too.

[vascop]

What kind of a TV have you got (make and model)? And especially what type of screen technology? Plasma? LCD?

[R1Geezer]

It's an LCD now but I saw it also on my old CRT, I don't think It's anything to do with the TV, I've seen it on many different TV's including projections. It's just somthing I've noticed many times in the past but never really got an answer for the phenomenon.

[wildwood]

automatic focusing using fuzzy logic?

[PeteHull]

Probably the ball traveling as fast as the camera is scanning, you get the same effect when viewing cars on screen, if they have spokes then they are seen to slow down and even start going backwards or freeze, I could never understand this when I was a kid and we saw wagons in the cowboy pics. Then it all came clear when I learned about TVs.

Hth

Pete

[Tim123]

The wagon wheel effect is caused by a phenomenon called temporal aliasing. If, in a TV picture, a spoke is vertical, then in the next picture the wheel has revolved so that another spoke is vertical, it appears that the wheel is stationary.
http://en.wikipedia.org/wiki/Wagon-wheel_effec t

The cricket ball effect is probably due to interlace. On a TV picture, all the odd lines are displayed followed by the even ones. If an object has moved significantly between these frames, all sorts of odd effects can happen.
http://en.wikipedia.org/wiki/Interlace