Factors that determine the degree of frozen time in a photograph

Here are five simple factors to help you to control amount of motion blur in your photos:

The other four factors being equal,

1. The faster the shutter speed, the more frozen the motion will be rendered.

In order to freeze the motion of the camera itself if you are hand-holding it, the shutter speed must be equal to or faster than the numerical equivalent to 1/focal length of the lens you are using. Example: While using a 100mm focal length, you would need to use a shutter speed of 1/100 of a second or higher to froze the subject.

If you use camera that has crop factor, then you need to multiple it with the crop factor. Majority of DSLR in the market has crop factor of varying degree. Canon has 1.6 and 1.3, Nikon, Pentax, Sony has 1.5, and Olympus and Panasonic has 2. If you use Canon camera, then you need to shoot at 1/160 or faster.

2. The faster the subject or camera itself is moving, the faster the shutter speed must be in order to freeze the movement.

Example: Basketball players move a lot faster than an old lady walks in the park. Therefore you need a faster shutter speed to freeze basketball player. Usually, around 1/250 to 1/500.

3. The more parallel to the lens axis the motion, the more frozen it will be.

In other words, a subject moving toward or away from the camera will be rendered frozen at a slower shutter speed than a subject moving across (perpendicular to) the camera’s field of vision.

4. The further the camera to subject distance, the more frozen the motion will be.

If the subject is very close to you, you will need a fast shutter speed to freeze it, even though they are moving in relatively slow speed.

5. The shorter the focal length of the lens, the more frozen the motion will be.

This is because shorter focal lengths (wider angle lenses) provide less magnification. Conversely, when a macro or close-up lens is used the movement of the subject and camera are magnified, so a faster shutter speed is needed to freeze motion.

I hope this is helpful to control amount of blur in your photograph.

Source:
The Elements of Photography: Understanding and Creating Sophisticated Images
by Angela Faris Belt

It is about two years now, but It has many valuable information for beginners both artistically and technically.