Movement
There are several factors which can influence the shutter speed we need to use to freeze a moving object:
1. The distance between us (the camera) and the object we are trying to photograph: The farther the object is from us, the less shutter speed we will need to freeze a moving object. Therefore, If we shoot the same object using the same shutter speed, but in one photograph we are 2 metres away and in the other photograph we are 10 metres away; the 2-metres photograph will register more movement than the 10-metres photograph.
When I took this photograph, I was driving on a highway. In this case, the object wasn't moving; I was moving. The photograph as taken using a shutter speed of 1/320, or in other words, very fast. Notice how the tall grass in front (and consequently, closer to the camera) appear to be more "moved" than the trees which ar further back. As a matter of fact, the trees look frozen.
2. The shutter speed at which the object is moving. The faster the object is moving, the higher the shutter speed we need to freeze it. It is not the same to photograph a race car than a bicycle, both running, of course. If we want to shoot a moving race car, we will need a much higher shutter speed to freeze it than the shutter speed we would need if we were shooting a running bicycle.
This photograph was taken from a moving vehicle. It was shot using a shutter speed of 1/250. Even though the car was moving fairly slow, around 30km/hour, I needed a higher shutter speed to be able to freeze the image.
Using the previous example; in this photograph, I used a shutter speed of 1/60 to freeze the image. Since the subject I was shooting was moving more slowly, I needed a slower shutter speed to freeze him.
