Question about tracking and shooting objects moving at high speed

I've seen a lot of shots or motorcycle and car racing and I see 2 types of shots. One is where anything and everything in the shot os frozen, and in the other, the subject is frozen but there is a motion blur in the background, as in the stands or the fans behind the track.

What is the technique used? In both scenarios you're tracking and moving the camera with the moving subject so how do you create this effect.

I'm sure anyone that knows what I'm talking about doesn't need to see an example but if anyone does I can point you to a few images that demonstrate both types of shots.

For a little background blur, use a shutter speed of less than 1/250th. The exact effect is dependant on the speed the subject is moving, so this is a ball park figure, and you really need to suck it and see...

To freez everything you need s fast shutter around 1/1500 or above.
to get background motion blur you Pan with the subject at a much slower SS around 1/200 .
Good Panning at a slow SS will make the subject still in relation to the camera but the background will in effect be moving in relation to the camera .
Rob

bildeb0rg wrote in post #4244408
For a little background blur, use a shutter speed of less than 1/250th. The exact effect is dependant on the speed the subject is moving, so this is a ball park figure, and you really need to suck it and see...

Thanks bildeb0rg

GyRob wrote in post #4244413
To freez everything you need s fast shutter around 1/1500 or above.
to get background motion blur you Pan with the subject at a much slower SS around 1/200 .
Good Panning at a slow SS will make the subject still in relation to the camera but the background will in effect be moving in relation to the camera .
Rob

Thank you Rob. I thought it was something like that but had no idea of what range of shutter speeds would creat the effect.

And logically, the faster the subject, the higher the shutter speed that will still blur the background-- ie a distance runner would need a relatively slow speed to blur the background (say, 1/50) , but a race car would be getting good blur at 1/200.

That makes perfect sense. Thanks Alex.

The background blur technique is called panning. To keep a moving subject looking sharp while using a slow shutter speed requires skill. The better you are able to maintain the subject in the same position in the frame while panning, the sharper it will appear. Thus you must move the camera in synchronization with the subject. To obtain a background with a long streaked blur may require a shutter speed of 1/15 sec or slower.