"A still photograph is called a still photograph because the picture doesn't move, not because the objects in the picture are not in motion. The photographer's mission, should he decide to accept it, is to capture motion with stillness."
The panning technique is nothing but moving the camera in a steady sweep, to keep the subject in the same spot on the viewfinder. In short, you have to pan the camera to keep up with the moving subject, to make your subject stand out in the picture. Panning helps render motion to an otherwise still image.
It is also used to make the subject stand out from the background. Panning is essentially like clicking a picture in the panorama mode, where you move the camera slowly from one point to another along the same horizontal plane.
This allows the viewer to assume the biker is cycling down in full speed, thus, giving the picture motion.
The main idea is to keep the subject in a specific area of the viewfinder, and follow it to the end of the panning area. The key is to fire the shutter right in the middle of the sweeping motion, and to continue panning till the subject leaves the focal point.
What this means is, you shoot your subject from the point it begins passing you till the point it has crossed your line of vision.
Start by using cameras with shutter speeds of 1/30th to 1/60th of a second, to excel in the art of panning. Remember, the essence of the panning technique lies in the blur it creates.
The key thing to remember about using a slow shutter speed is that, anything that moves in the scene will blur. Which means, you ought to never let your focus falter while panning, or else, you will end up with a blurred subject, along with a blurred background.
Take the limbs of the leopard for instance. Due to the motion, it is normal to allow it to blur. The same effect is not desired of the main body, which has been correctly put in focus.
Ensure that your camera is stable on a stand, with its lens facing the direction of the action. In case of a race, assume your subject to pass right in front of you, and set up the camera accordingly. Just when the subject enters your range of vision, depress the shutter halfway through. Shoot when the subject is directly in front of you.
Ensure that you have the subject at a specific point on the viewfinder from the time you depress the trigger to the point your subject has left the frame a while after the shot has been taken.
A piece of advice-you would rather not trust the LCD of the camera while experimenting with this technique. Shoot in the manual mode, and peep through the viewfinder to get your shot right. At the same time, remember not to shake the camera so as to end up with noise in your final picture.