The time has come that I have to talk a little about lenses before I move on. It is important to understand the attributes of your lenses in order to fully grasp the next couple of lessons. In the next few moments, I will discuss the different types of lenses, focal length and aperture.
TYPES OF LENSES
There are two major types of lenses in the camera world, primes and zooms. Both have there pros and cons. There are also several specialty lenses, however, I will save those for later discussions.
A prime lens is one that does not change the focal length. For example, a prime lens is one with a fixed focal length such as the Canon 50mm lens. The best way to possibly describe this, is that the photographer moves to frame the picture before snapping the shutter. They usually have the advantage of being bright because of lower aperture (more on this later) and are usually a very high quality. A disadvantage of course is that you have to have many lenses for different focal lengths or be stuck running around trying to fill the frame.
A zoom lens is one that does allow the photographer to change the focal length of the lens without changing the lens. A good example of this, is the Canon 24-70 mm zoom lens. In this case, the camera can have a wide angle view (24mm) or a standard view (70mm). The photographer in this case does not have move in order to fill the frame. He or she can stay in one place and change the view of the picture by “zooming” (changing the focal length) the lens. The advantages of the zoom are that they are useful where you require a range of focal lengths but want the convenience of a single lens, whether for weight (only carrying one lens), always being ready to take the picture or shooting in a dusty environment and you want to keep dust from entering the camera to a minimum. The disadvantages are that zooms are usually slower than prime lenses (higher apertures) and are therefore darker. The picture quality from zoom lenses are sometime questionable depending on the lens. This is an area where one really gets what he or she pays for. …more to follow shortly…this lesson is incomplete.