What Maxwell said... Slower shutter speed and panning...
Now, you asked about panning technique.
- preplan where you will take the shot.
- use MANUAL focus and prefocus on the spot where you want the car to be in the shot
- stand correctly... by this I mean stand with your feet and shoulders parallel to the path of the car where you want the photo to happen.
- wind yourself up... if the car is moving left to right keep your feet in place and swivel your upper body to the left.
- as the car approaches and enters the frame let yourself "unwind" to the right.
- click the shutter as the car becomes parallel to your feet
- continue to swivel to the right as the car moves away. you will stop naturally at some point. don't force or anticipate it.
what this does is turns you into a sort of a spring where the naturally smoothest period of motion is right in the middle of the movement. it takes practice to unwind at the same sideways "speed" as the car but you should notice improved results right away.
this is exactly how I took this shot...
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