Question

[Simple]

The picture I posted of the motorbike has only one part of the picture in sharp focus (during panning) How does that happen? Has that effect got a name? I ask because when I understand it, it might be practiced and used more effective. Excuse my ignorance on this.

[Beaux Reflets]

My guess is that you stopped or paused in the smooth panning motion or the camera rotated a wink as you pressed the shutter; with the cameras software Auto Focus center weighted"?, kicking in. 

[Simple]

Thanks Andy, If it was the first or last picture of the series (Shot at 9 fps)series of 7pictures. I would agree. I asked a sports journalist yesterday and he told me it was the angles of the bike coming toward me. You would only get everything sharp if the bike or car is at straight angles with the camera. Under an angle the front and rear of the bike move away closer to the camera than the part where you have focussed. (assuming you have continuous focus on) the focussed part is OK but the rest is moving at different speeds.
The effect can be reduced by being further away from the bike and using longer lens, and ofcourse speed of bike and shutter. The latter will be detrimental to the panning effect ofcourse. It took me a while to get my head around it, but it makes sort of sense now.